The Journal of Bone & Joint Surgery

The Journal of Bone & Joint Surgery, Volume 92, Issue 18

Specialty Update | December 15, 2010

What's New in Total Hip Arthroplasty

Michael H. Huo, MD¹; Kristopher G. Stockton, MD¹; Michael A. Mont, MD²; Javad Parvizi, MD, FRCS³

¹ Department of Orthopedic Surgery, UT Southwestern Medical Center, 1801 Inwood Road, Dallas, TX 75390-8883. E-mail address for M.H. Huo: michael.huo@utsouthwestern.edu
² The Rubin Institute for Advanced Orthopaedics, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, MD 21215
³ Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University School of Medicine, 925 Chestnut Street, Philadelphia, PA 19107

View Disclosures and Other Information

Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors, or a member of his or her immediate family, received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from commercial entities (Stryker Orthopaedics, Smartech, Wright Medical).

Investigation performed at UT Southwestern Medical Center, Dallas, Texas; Sinai Hospital of Baltimore, Baltimore, Maryland; and Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania

Specialty Update has been developed in collaboration with the Board of Specialty Societies (BOS) of the American Academy of Orthopaedic Surgeons.

J Bone Joint Surg Am, 2010 Dec 15;92(18):2959-2972. doi: 10.2106/JBJS.J.00851

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Extract

Total hip arthroplasty remains one of the most efficacious orthopaedic reconstructive procedures. This specialty currently faces several challenges, including increasing patient volume, reduction in the number of specialty arthroplasty surgeons performing this procedure, costs, and controversies centered on product liability and implant bearing surfaces. We have included the latest information from publications in major journals as well as abstracts of presentations at the 2010 Annual Meeting of the AAOS (American Academy of Orthopaedic Surgeons), the 2010 Annual Meeting of the ORS (Orthopaedic Research Society), the 2010 Open Meeting of The Hip Society, the 2009 Annual Meeting of the AAHKS (American Association of Hip and Knee Surgeons), and the 2009 fall meeting of The Hip Society.

Figures in this Article

Introduction

This update is divided into five sections: (1) clinical outcome of primary and revision total hip arthroplasty, (2) hip resurfacing arthroplasty, (3) implant bearing surfaces, (4) socioeconomic and practice management issues, and (5) complications. We will in particular focus on hip resurfacing arthroplasty and the metal-on-metal bearings as the most publicized topics among orthopaedic surgeons and in the lay press.

Clinical Outcome of Primary and Revision Total Hip Arthroplasty

Acetabular Fracture

Many advances have been made over the past three decades in the surgical treatment of acetabular fractures. Some patients later develop posttraumatic arthritis, osteonecrosis, and the need for total hip arthroplasty. Matta¹ performed a survivorship analysis on 706 acetabular fractures that were treated by a single surgeon with use of open reduction and internal fixation over three decades. The twenty-year survival rate was 78%. Factors that were identified as being predictive of poor outcome included older age, femoral head damage, articular impaction, incongruency of the acetabular roof, and displacement of >1 mm. Surprisingly, a worse outcome was seen in patients with simple fracture patterns in contrast to more complex patterns. Swanson and Huo² presented data on ninety conversion total hip arthroplasties in ninety patients with previous acetabular fractures. The mean age at the time of the injury was forty-four years, and the interval between the injury and the total hip arthroplasty was 3.5 years. Cementless fixation was used in 89% of the hips. The mean duration of follow-up was three years. The mean Harris hip score was 89. Revision surgery was necessary in fifteen hips (17%). Pellegrini and Sterling³ presented data on the use of frozen-section histopathological analysis to determine the presence of infection in a study of twenty-seven patients who underwent conversion total hip arthroplasty following previous surgical treatment of an acetabular fracture. The conversion total hip arthroplasties were performed an average of 1.6 years after the initial procedures that were done for the treatment of the acetabular fractures. No patient with negative histopathological findings (<10 polymorphonuclear leukocytes/high power field) developed an infection. Only one patient (3.7%) developed infection and had two positive frozen sections demonstrating high numbers of polymorphonuclear leukocytes. The sensitivity and specificity of using frozen-section histopathological analysis to detect infection at the time of total hip arthroplasty were 100% and 97%, respectively.

Acetabular Cup Revision

Massive acetabular bone deficiency is perhaps the most challenging reconstruction in revision total hip arthroplasty surgery. Surgical options include structural and morselized bone-grafting, metallic augments, use of a pelvic reinforcement cage or ring, and major column acetabular allograft. Ries and Hansen⁴ reported on their experience with forty-three consecutive acetabular revisions involving a cage. The mean duration of follow-up was nearly six years (range, two to eight years). All of the deficiencies were classified as Paprosky type-2C or greater, with 33% of the patients having pelvic discontinuity. The most common complication was infection (prevalence, 17%). Cage reconstruction failed in 21% of the patients with pelvic discontinuity. Gross et al.⁵ reported on ninety-six acetabular revisions that had been performed with use of major column allograft; the mean duration of follow-up was twelve years (range, six to twenty-four years). Acetabular reinforcement cages or rings were used in eighty-one hips (84%). Re-revisions were necessary in 40.6% of the hips, with 27.5% of the failures being due to graft resorption. Dislocations occurred in 10.4% of the hips. The overall twelve-year survival rate was 59.4% for the cup and 88.5% for the column allograft. These results clearly underscore the challenges in addressing major acetabular bone deficiencies.

Revisions with use of morselized bone-grafting and large cementless cups with screws are efficacious provided that the bone deficiency does not compromise the structural integrity of the acetabulum. Clohisy et al.⁶ reported on thirty-eight cup revisions that were performed with this technique in a series of 434 revision total hip arthroplasties from one institution. The mean area of the osteolytic lesion was 14.1 cm². The mean duration of follow-up was 4.4 years, at which time 86% of the cups were stable and functioning well. Complete bone graft incorporation was evident in 65% of the hips.

Kishida et al.⁷ demonstrated that the addition of hydroxyapatite to bone graft enhanced the mechanical strength of the graft. The investigators demonstrated a reduction in cup migration in a model of an impaction grafting technique with cement fixation with use of a mixture of cancellous bone chips and hydroxyapatite in contrast to bone graft alone. Further testing of this technique with cementless cup fixation is warranted.

Fixation loosening remains one of the leading reasons for revision surgery. Many investigators believe that inflammatory responses are associated with aseptic loosening. Markel et al.⁸ measured peripheral blood CD14+ and CD16+ monocytes in patients with aseptic loosening and in those with stable total hip arthroplasty implants and noted higher levels (p < 0.05) in patients with loose implants. Following revision surgery, there was a significant reduction of monocyte levels as well as a marked improvement in pain and joint function. Monocyte levels could be used for the diagnosis and confirmation of aseptic loosening. There is also the potential that pharmacological or physical modalities that modulate monocyte levels could enhance clinical outcome following revision surgery.

Several novel porous biomaterials, similar to cancellous bone with regard to structural geometry, porosity, and the modulus of elasticity, have been developed and introduced into clinical practice over the past several years. Huddleston et al.⁹ evaluated the osseous response to three novel porous materials (titanium foam, cobalt-chromium foam, and tantalum foam) by comparing these materials with implants coated with conventional titanium beads in an intramedullary rod model in rabbits. The reported porosity was 68% (titanium), 69% (cobalt-chromium), and 75% to 85% (tantalum). The pore sizes ranged from 400 to 600 µm for all three materials. High-resolution contact radiographs of each section of the femur and tibia were made after the animals were killed, and the appositional bone index (ABI) was measured. The ABI was significantly lower (p < 0.05) in association with the titanium foam material than with either the cobalt-chromium foam or the conventional titanium beads at three weeks. There was a nonsignificant difference between the titanium foam and the tantalum foam materials. There was no difference among the four materials at twelve weeks. These novel biomaterials all have different structural, biomechanical, and biological properties, and any differences in the clinical performance of implants made from these biomaterials remain to be established.

Hip Resurfacing Arthroplasty

Hip resurfacing arthroplasty has been one of the most controversial issues in orthopaedic surgery over the past five years. There has been an intense clinical interest in hip resurfacing arthroplasty following its approval by the United States Food and Drug Administration (FDA). However, there are increasing concerns over metal-on-metal bearing couplings. We will focus initially on the latest information on clinical outcomes, comparison with conventional total hip arthroplasties, rehabilitation, risk factors for failure, and navigation. Metal ion serum levels and the adverse local tissue reactions will be discussed later.

From the perspective of health system resource utilization, Bozic et al.¹⁰ conducted a Markov decision model analysis to compare the quality-adjusted life-years and costs associated with hip resurfacing compared with conventional total hip arthroplasty. The authors concluded that hip resurfacing arthroplasty could be clinically advantageous and cost-effective for younger men and women. However, they recommended further research on the comparative effectiveness with use of quality outcome measures in addition to traditional hip scores to better define any differences between these procedures.

A recent report by De Smet et al.¹¹ included the consensus opinions of twenty-one leading orthopaedic surgeons who had a combined clinical experience with >18,000 hip resurfacing arthroplasties. Some important findings reported by this panel were that (1) 81% of the members believed that a surgeon should not perform hip resurfacing arthroplasty until having performed a minimum of 200 conventional total hip arthroplasties, (2) the best candidate for this procedure was a male patient with primary osteoarthritis, (3) 89% of the members did not believe that female patients should be excluded, and (4) most surgeons would exclude patients of child-bearing age (66%), those with a metal allergy history (70%), and those with abnormal anatomy of either the acetabulum or the proximal part of the femur (83%). However, there was no consensus with regard to the utilization of preoperative metal allergy testing as a selection criterion.

Clinical Outcome

Several centers have reported good results with resurfacing arthroplasty after intermediate to long-term follow-up. Randelli et al.¹² reported a 95.4% probability of implant survival over ten years with revision for any reason as the end point. Amstutz et al.¹³ reported on the first 100 hip resurfacing procedures (in eighty-nine patients) with a minimum of ten years of follow-up. The ten-year survival rate was 88.3%. The survival rate was 100% for hips with a femoral component size of >46 mm. Because of refined selection criteria, surgical technique, and instrumentation, the authors anticipated even better results for patients who had undergone surgery more recently in their large series of >1000 hip resurfacing arthroplasties.

The prevalence of groin pain after resurfacing arthroplasty is higher than that after conventional total hip arthroplasty, although the cause is unclear. One possible etiology is iliopsoas tendinopathy resulting from impingement. Bin Nasser et al.¹⁴ reported an 18% prevalence of groin pain in a study of 116 patients, with 57% of the patients reporting limitations of daily activities due to groin pain. However, only 10% used analgesics for the relief of pain.

Comparison of Hip Resurfacing with Conventional Total Hip Arthroplasty

Controversies remain with regard to whether hip resurfacing is superior to conventional total hip arthroplasty. Fowble et al.¹⁵ compared fifty-five patients (fifty-five hips) who were managed with hip resurfacing with thirty-five patients (forty-five hips) who were managed with conventional total hip arthroplasty. The patients were followed prospectively for two to four years. The patients in the hip resurfacing group had higher activity scores but also had a higher prevalence of hip pain. However, the patients in the hip resurfacing group also had higher preoperative function and health status, so it was unclear whether the higher postoperative outcome was due to the surgery or to patient-related factors. Zywiel et al.¹⁶ conducted a prospective study in which thirty-three patients who were managed with hip resurfacing were compared with thirty-three matched patients who were managed with conventional total hip arthroplasty. Importantly, the investigators did control for the preoperative activity level and other demographic factors. While there were no differences between the groups before surgery, the patients in the resurfacing group did have higher postoperative activity levels than those who were managed with conventional total hip arthroplasty.

Garbuz et al.¹⁷ randomized 107 patients to either hip resurfacing or conventional total hip arthroplasty. There was no detectable difference between the groups in terms of quality of life at the time of short-term follow-up (mean, 1.1 years). Stulberg et al.¹⁸ reported no difference in the functional status between 337 patients managed with unilateral hip resurfacing and 266 patients managed with unilateral total hip arthroplasty. Hall et al.¹⁹ reported no difference between hip resurfacing (thirty-three hips) and total hip arthroplasty (thirty-nine hips) in terms of patient-reported outcome measures. In summary, current data demonstrate little detectable clinical outcome difference between hip resurfacing arthroplasty and conventional total hip arthroplasty.

Rehabilitation and Functional Activities

Femoral neck bone density was evaluated in thirty-two patients by Cooke et al.²⁰, who noted a decrease in bone density six weeks and three months after resurfacing arthroplasty, with a return to preoperative values at one year. The authors recommended modification of physical activities during the first year in order to reduce the risks of a femoral neck fracture, especially in patients with a reduction of bone density in the femoral neck prior to surgery. Banerjee et al.²¹ evaluated the questionnaire responses from 138 patients (152 hips) following resurfacing arthroplasty. While the patients engaged in sports more frequently after surgery than before surgery, they participated less frequently in high-demand sports but more frequently in low-impact sports.

Risk Factors for Failure

Patient Selection

Patient selection consistently has been cited as one of the most important factors related to the outcome of hip resurfacing arthroplasty. The Australian Orthopaedic Association National Joint Replacement Registry includes data on 12,093 hip resurfacing arthroplasties performed between September 1999 and December 2008. Prosser et al.²² compared the results of hip resurfacing arthroplasties with those of conventional total hip arthroplasties that were done during the same nine-year period. While a higher revision rate was seen in women than in men, the rates were no different when adjustment was made for femoral component size. A higher failure rate was observed in association with a femoral component size of <50 mm. At eight years, the cumulative revision rate was 5.3% for hip resurfacing, compared with 4.0% for conventional total hip arthroplasty. The revision rate was only 3.0% for patients younger than fifty years old with osteoarthritis who had a femoral component size of >50 mm. There were also differences in the revision rate as a function of disease etiology and implant design. Corten and MacDonald²³ analyzed registry data and concluded that the best results were seen in younger patients with osteoarthritis and a large femoral component size. McBryde et al.²⁴ analyzed a registry of 1826 patients (2123 hips) from the United Kingdom and found results that were similar to those based on the Australian Registry data. The revision rate was associated with female sex (p = 0.014) and decreasing femoral component size (p < 0.001). Revision was not associated with age, surgeon, surgeon experience, or surgical approach. A multivariate analysis demonstrated that sex was not an independent risk factor for failure.

Component Positioning

Several studies have demonstrated the importance of optimal cup positioning with regard to wear, metal ion levels, and the revision rate. It has long been established that the ideal cup position for conventional total hip arthroplasty is abduction in the range of 35° to 45° and anteversion in the range of 10° to 25°. In order to reduce the risk of impingement between the femoral component or femoral neck and the edge of the cup, the cup designs used for resurfacing arthroplasty and those used in conjunction with large-diameter metal-on-metal conventional total hip replacement are not a symmetrical hemisphere. Therefore, there is an increased risk to insert these metal-bearing cups at a steeper angle. This risk has been shown to be design and size-dependent. Jeffers et al.²⁵ found that the critical bearing surface of six different cup designs was, on the average, at an angle of up to 16° greater than the perceived cup abduction angle. For example, a cup placed at 45° would be similar to a conventional acetabular shell (for a metal-on-polyethylene coupling) placed at up to 61°. High cup angle has been consistently reported to lead to greater wear and higher serum metal ion levels. De Haan et al.²⁶ examined the metal ion levels as a function of cup angle in a study of 214 patients managed with hip resurfacing. Significantly greater cobalt (p = 0.002) and chromium (p = 0.003) levels were found in the patients with a cup angle of >55°. Patients with smaller cup sizes were especially at risk of placement at a higher abduction angle. Isaac et al.²⁷ also confirmed a correlation between higher serum metal ion levels and high cup angle in a study of seventy-four patients managed with hip resurfacing. Grammatopoulos et al.²⁸ evaluated the development of pseudotumors following hip resurfacing as a function of cup position and found that cups that were placed within a "safe" zone of anteversion of 20° ± 19° and inclination of 40° ± 10° were associated with significantly lower prevalence of pseudotumors (six of twenty-seven hips) in comparison with those that were outside this optimum range (twenty-five of thirty-one hips) (p < 0.01). Data from these studies underscore the importance of further refinement of surgical training, instrumentation, and perhaps the use of computer navigation to optimize cup position in metal-on-metal hip arthroplasties.

A new type of software, namely, EBRA (Einzel-Bild-Roentgen-Analysis), was developed at the University of Innsbruck in Austria²⁹. It is proposed to be among the most accurate technologies to measure acetabular cup position. It is hoped that this technology could facilitate surgeon training, allow for improved patient evaluation, and be used to predict which hips may be at a higher risk for early failure.

Designs

Poorer results have been reported in association with specific implant designs. In a series of 660 hip resurfacing arthroplasties, Langton et al.³⁰ reported a 3.4% rate of early failure and noted that all early failures were associated with the same implant design. In addition to implant design, other risk factors included smaller component size, higher cup anteversion angle, and higher serum cobalt and chromium ion levels (p < 0.001 for all). Daniel et al.³¹ reported a 16% rate of revision and a 24% rate of radiographic loosening at a mean of 7.3 years (range, 1.2 to 10.9 years) in a study of 184 hips (160 patients) who were managed with a device that was double-heat treated. These data further support the utility of an implant registry to allow early detection of devices with suboptimal clinical performance.

Femoral Neck Erosion

Ball and Schmalzried³² reported the presence of small cortical erosions in the posterior femoral neck in fourteen (20%) of sixty-nine hips at a mean of fifteen months (range, six to twenty-four months) following hip resurfacing arthroplasty, possibly as a result of femoroacetabular impingement. No erosions progressed over the subsequent two to seven years. Joseph et al.³³ reported femoral neck erosions in 98% of sixty-one hips at the time of the two-year follow-up, with a positive correlation between the change in abductor moment arm and femoral neck erosion (p < 0.01). They concluded that the altered biomechanical loading patterns with subsequent adaptive bone remodeling led to femoral neck thinning and erosion.

Revision of Failed Resurfacing Arthroplasty

Most surgeons believe that revision of a failed hip resurfacing arthroplasty would result in a clinical outcome equivalent to those of total hip arthroplasty. Conflicting data have been reported. De Steiger et al.³⁴ evaluated the results of 397 revision procedures from the Australian hip resurfacing registry and reported that acetabular revision alone had very poor results in contrast with femoral revision or both-component revision. The five-year re-revision rate was 20% after revision of the cup alone, 7% after revision of the femoral component alone, and 5% after revision of both components. In contrast, Eswaramoorthy et al.³⁵ reported comparable clinical outcomes in a study in which twenty-nine revisions were compared with routine primary total hip arthroplasties.

Computer-Assisted Navigation

Beckmann et al.³⁶ performed a systematic review and meta-analysis of the use of navigation to improve cup position in total hip arthroplasties. The literature search dates were from January 1976 to August 2007. Of the 363 citations originally identified, only five trials with 400 patients met the inclusion criteria and were selected for analysis. The mean cup inclination and anteversion angles were not significantly different between the conventional treatment and navigation groups. Navigation reduced the variability in cup positioning and the risk of placing the acetabular component beyond the safe zone. The authors concluded that navigation was a reliable tool for optimizing cup placement and for minimizing outliers. However, long-term outcomes and cost-utility analyses were not available in the literature. Renkawitz et al.³⁷ presented a comprehensive review of the current status of computer-assisted technology in orthopaedic surgery. One of the most exciting new developments is that of software algorithms that analyze the cup and the stem as a coupled biomechanical system to assist the surgeon in optimum component positioning for each individual patient. Improvement in patient outcomes and the durability of implant fixation resulting from the use of navigation technologies remain to be validated.

The optimization of hip offset is very important. Dorr³⁸ used navigation techniques to optimize offset in eighty-two patients who underwent unilateral total hip arthroplasty. The offset was within 6 mm of that of the contralateral hip in seventy-eight hips (95%). Manzotti et al.³⁹ conducted a study in which forty-eight hips undergoing total hip arthroplasty with navigation were compared with a matched cohort of forty-eight hips that were treated with conventional guides. They reported less leg-length discrepancy in the navigation group. Ryan et al.⁴⁰ confirmed the accuracy of an imageless navigation system for cup insertion with use of postoperative computed tomography (CT) scans.

However, it is important to recognize that relying completely on navigation technology is not necessarily the best clinical practice at the present time. Schnurr et al.⁴¹ analyzed thirty-two hip resurfacings that were performed with navigation in cadavers. Their data demonstrated good accuracy with regard to the achievement of optimum varus-valgus angles. However, on occasion, the software calculation was inaccurate and clinical judgment was necessary to achieve the best component position. Olsen et al.⁴² urged caution with the reliance on navigation data alone and emphasized the importance of preoperative templating. Misleading information may be registered intraoperatively and may lead to inaccurate femoral component sizing and positioning.

It is difficult to optimize component positioning to avoid impingement in patients with severe cam-type deformity. Antoniou et al.⁴³ generated surface arthroplasty simulations with use of three-dimensional CT scans for sixty-one consecutive patients and used the data to determine the optimal surgical technique. They found that cam-type deformity required a more superior entry point and greater reaming depth. Safe insertion of the femoral component could be done with use of this model even with progressive deformity of the femoral head. Pitto et al.⁴⁴ reported inaccuracies between the navigation system and measurements for guide-pin placement with use of microcomputed tomography, especially as femoral head and neck deformity increased.

Implant Bearing Surfaces

Metal-on-Metal

A highly visible controversy today involves the biological responses around metal-on-metal bearings. There have been increasing reported and published data on the potential adverse effects of metal-on-metal couplings in the past year. The adverse reactions have been found in association with both conventional total hip implants with large-diameter metal-on-metal articulations and hip resurfacing implants. The most common problem has been macrophage and lymphocyte responses that may be due to poor component positioning, which in turn results in increased wear and metal ion release. Specific prosthetic designs may be especially at risk. In some cases, investigators have documented histological characteristics similar to delayed type-IV hypersensitivity to metal ions. There has been an intense media exposure of these infrequent complications by the lay press.

There currently are no definitive data with regard to the prevalence of adverse problems related to metal-on-metal bearings in total hip arthroplasty. Potter et al.⁴⁵ have been using magnetic resonance imaging (MRI) to evaluate periprosthetic soft tissues around total hip arthroplasties for nearly a decade. In a recent report on thirty hips (twenty-seven patients) managed with hip resurfacing arthroplasty, nineteen hips were painful and eleven were asymptomatic. The mean interval between the hip resurfacing procedure and MRI was 1.8 years. Important MRI findings included synovial expansion (prevalence, 77%), femoral neck erosion (15%), osteolysis (11%), and pseudotumors compressing the neurovascular structures (7%). The investigators acknowledged the need for further refinement of the imaging software and technique in order to reduce metal artifacts and to enhance its accuracy as a diagnostic tool.

Adverse Tissue Reactions

Adverse soft-tissue reactions to metal-on-metal devices most commonly present clinically with pain. Glyn-Jones et al.⁴⁶ reported that twenty-two (1.8%) of 1224 patients who had undergone hip resurfacing arthroplasty had a revision specifically for the treatment of pseudotumors. Significant risk factors for the development of pseudotumor included female sex (p < 0.001), an age of less than forty years (p = 0.003), small component size (p = 0.003), and hip dysplasia (p = 0.019). The revision rate for men was 0.5% at eight years. The revision rate was 6% for women who were more than forty years old but was 13.1% for younger women. O'Neill et al.⁴⁷ analyzed the Canadian registry for hip resurfacing arthroplasties. The overall revision rate was 3.2%, with the most common cause being femoral neck fractures (1.6%) and not adverse tissue reactions or unexplained pain. Beaule et al.⁴⁸ reported only three cases of pseudotumor (0.09%) following >3400 hip resurfacings in the Canadian registry that were performed between 2002 and 2008. Schmalzried et al.⁴⁹ reported their own experience with 585 consecutive hip resurfacing arthroplasties that were followed for a mean of four years (range, one to fifteen years). Two patients required exploration for joint debridement because of symptoms of synovitis at thirteen and twenty-one months after surgery. The implants were retained in both hips. Both patients remained asymptomatic for up to four years after the debridement. Two additional patients, each with bilateral hip resurfacing, underwent revision because of pain in both hips. The histological findings were consistent with aseptic lymphocytic vasculitis-associated lesions in all four hips. In summary, the rate of reoperation for any adverse tissue response was 1% (six of 585). Malviya and Holland⁵⁰ reported a 0.15% prevalence of pseudotumors in another consecutive series of 670 resurfacing arthroplasties.

It is well recognized that specific histological characteristics are associated with failures of metal-on-metal articulations. Zustin et al.^51,52 analyzed the histological findings for 181 femoral heads that were retrieved following the failure of hip resurfacing. Lymphocytic infiltrates within the bone were present in 34.2% of the specimens, with the infiltrates being graded as excessive in 5.5% and as mild or moderate in 28.7%. This finding was more frequent in women than in men (p < 0.05). The authors hypothesized that the pain could be caused by excessive intraosseous lymphocytic infiltrates due to delayed hypersensitivity reaction to metal debris. In specimens that were retrieved following revisions that were performed because of aseptic loosening, the investigators found fibrocartilaginous metaplasia with interface hyperosteoidosis along with the lymphocytic infiltrates. They concluded that these histological changes could be the precursor to delayed hypersensitivity leading to loss of fixation at the bone-cement interface. The same investigators further analyzed the retrieved specimens from 107 patients who underwent revision because of a femoral neck fracture and found osteonecrosis but no evidence of inflammatory infiltrate. Hart et al.⁵³ analyzed the tissues from seventy-seven hips with failed hip resurfacings and from eight hips with failed conventional total hip arthroplasties with a metal-on-polyethylene coupling. The authors noted surface necrosis, macrophage infiltrates, and perivascular B-lymphocyte aggregation in thirty-four (44.2%) of the seventy-seven hip specimens from the resurfacing group; these features were not observed in the total hip arthroplasty group.

Mahendra et al.⁵⁴ analyzed the periprosthetic soft tissues and the retrieved femoral heads from fifty-two hips that underwent revision because of femoral neck fracture (twenty-one hips), pseudotumor (thirteen hips), loosening (nine hips), and other causes (nine hips). They found tissue and bone necrosis in twenty-eight hips (54%), with necrosis being noted in every hip that was revised because of pseudotumor (100%). Diffuse inflammatory cell infiltrate, thought to be due to cytotoxicity as a result of delayed hypersensitivity to metal debris, was seen in forty-five (87%) of the fifty-two cases.

In contrast, Kwon et al.⁵⁵ evaluated the tissues that were retrieved from patients with or without pseudotumors at the time of revision surgery and did not find any significant differences in lymphocyte reactivity to trace metal elements in the two groups. These data further contributed to the controversy about whether pseudotumor formation is primarily a function of hypersensitivity to metal ions.

Serum Metal Ion Levels

Garbuz et al.⁵⁶ reported the results of a prospective, randomized clinical study in which hip resurfacing arthroplasty was compared with large-head metal-on-metal total hip arthroplasty. Serum levels of cobalt and chromium were measured in a subset of thirty patients. There was a greater increase in the ion levels from preoperative values in the metal-on-metal total hip arthroplasty group than in the hip resurfacing group; specifically, there was a forty-six-fold increase in serum cobalt and a tenfold increase in serum chromium levels in the metal-on-metal total hip arthroplasty group, compared with a tenfold increase in cobalt and a 2.6-fold increase in chromium levels in the hip resurfacing group. The difference could be a reflection of the particular implant system used in the study. In fact, the authors recommended against using such metal-on-metal total hip arthroplasty implants.

Two recent studies detailed metal ion levels in maternal and placental blood following metal-on-metal hip arthroplasty. Ziaee et al.⁵⁷ presented a cross-sectional study in which twenty-five women who had hip resurfacing implants were compared with a control group of twenty-four women without any metal implants. They found that the difference in the maternal and cord blood metal levels was low (range, 5% to 7%) in the resurfacing arthroplasty group. Moreover, metal ion levels were significantly lower in the cord blood than in the maternal blood (cobalt, p < 0.05; chromium, p < 0.0001), suggesting some type of regulatory capacity against metal ion transfer across the fetal-maternal barrier. Jacobs and Novak⁵⁸ reported higher serum metal ion levels in three mothers with metal-on-metal hip prostheses (and their babies) in comparison with seven patients without implants and concluded the placenta can modulate metal ion transfer from maternal to fetal blood. Although the effects of metal ions on maternal and fetal subjects are unknown, the authors urged caution with respect to the use of metal-on-metal devices in females of child-bearing age.

Highly Cross-Linked Polyethylene

Highly cross-linked polyethylene has been in clinical use for over a decade. Improved wear characteristics of this material have been consistently reported in laboratory tests, on the basis of clinical wear measurements, and on the basis of evaluations of retrieved liners. Maloney et al.⁵⁹ reported on the prevalence of osteolysis in young patients (mean age, <50 years) with identical total hip arthroplasty implant designs with (fifty hips) or without (forty-nine hips) highly cross-linked polyethylene bearings. The mean duration of follow-up was 7.2 years. The prevalence of osteolysis was 2% for the highly cross-linked group, compared with 24% for the conventional polyethylene group (p < 0.0001). There was no correlation between head penetration measurements and the prevalence of osteolysis. Rubash et al.⁶⁰ specifically analyzed the wear of highly cross-linked polyethylene liners coupled with large-diameter femoral heads (>36 mm) and identified seventy-four hips with a minimum of five years of follow-up. The mean duration of follow-up was 6.4 years. The mean age was sixty-two years. There were no cases of osteolysis. The head penetration rate was no different among the three head sizes (36, 38, and 40 mm). The mean penetration rate for large-diameter heads was 24.7 ± 171.3 µm/yr. This rate was not different from the penetration rates for 28 and 32-mm heads coupled with the same highly cross-linked polyethylene (10.2 ± 80.7 µm/yr) (p = 0.48). This finding is important because more large-diameter heads are being used to improve the clinical performance of total hip implants and to reduce the risk of dislocation.

Currier et al.⁶¹ analyzed eighty-two retrieved bearings (sixty-one cup liners and twenty-one tibial inserts) made of either remelted or annealed highly cross-linked polyethylene. Oxidation was found in all of the retrieved bearings when they were compared with never-implanted bearings. Oxidation occurred both while the bearings were in vivo and with increasing shelf life following retrieval. However, oxidation was greater in the annealed materials in comparison with the remelted materials. Moreover, free radicals were detected in all of the specimens as well. Kurtz et al.⁶² analyzed 214 retrieved cup liners made of remelted, annealed, and gamma-sterilized polyethylene. Rim oxidation was observed in the annealed and gamma-inert polyethylene liners but not in the remelted liners. The amount of head penetration per year was significantly greater in the gamma-inert polyethylene group in comparison with the annealed and remelted polyethylene groups. The difference between the highly cross-linked and gamma-inert polyethylene was significant (p < 0.002). Rubash et al.⁶³ reported increased oxidation in a study of forty-seven cup liners made of both remelted and annealed highly cross-linked polyethylene as the shelf life increased after retrieval. The exact mechanism of this finding is unclear. Harris et al.⁶⁴, from the same laboratory, reported increased oxidation and reduced cross-linking in both remelted and annealed highly cross-linked polyethylene when subjected to cyclic loading with lipid (squalene) and artificial aging (70° at 5 atmospheres for fourteen days). Additional work is necessary to determine if there would be alterations in the material properties and the wear characteristics in vivo.

One of the potential limitations of first-generation highly cross-linked polyethylene was fatigue fracture of the material, particularly at the periphery of the cup liner or at the site of total knee arthroplasty bearings. Oral et al.⁶⁵ demonstrated similar but substantially better bending fatigue characteristics when a cross-linked polyethylene material made with exposure to vitamin E (a-tocopherol) was compared with conventional polyethylene. The same investigators reported laboratory testing data on a new experimental material with only surface cross-linking while maintaining optimum mechanical properties in the bulk of the material below the surface⁶⁶. There was a 33% improvement of fatigue crack initiation in comparison with remelted highly cross-linked (100-kGy-irradiated) polyethylene. Shear testing did not demonstrate any surface delamination of the material. Future highly cross-linked polyethylene may offer even better wear resistance with reduced risk for fatigue fracture.

Ceramic-on-Ceramic

Contemporary ceramic-on-ceramic bearings have been in clinical use for over a decade. Capello⁶⁷ reported additional data from a prospective study of total hip arthroplasties with such bearing coupling. The ten-year survival rate (with revision for any reason as the end point) was 96% for the ceramic-on-ceramic group and 91% for the metal-on-polyethylene group. The prevalence of liner fracture was 0.2%, whereas the prevalence of noise was 0.1%. Joint squeaking has been reported in association with all bearing surface couplings but has been the most publicized in association with ceramic-on-ceramic couplings. There have been some recent reports that different rates of squeaking were observed in association with different stem designs with identical ceramic-on-ceramic bearings. Hothan et al.⁶⁸ conducted a hip simulator study involving eight different stem designs, all with identical cup and bearing surfaces. Acoustic characteristics were very different among the different designs. Moreover, the initiation of squeaking was also different with different stems with regard to the number of cycles tested.

These data suggest that the femoral stem was an important factor with regard to the characteristics of and the susceptibility to squeaking.

Socioeconomic and Practice Management

Patient Satisfaction

Patient expectation has a potential impact on clinical outcome measurement. Mancuso et al.⁶⁹ assessed the expectations of 405 patients before and after total hip arthroplasty. The mean age at the time of surgery was sixty-six years. The mean duration of follow-up was 4.4 years. Only 43% and 32% of the patients reported that their expectations had been fulfilled "completely" and "somewhat," respectively. Predictors for achieving a high level of expectation fulfillment included younger age, active employment, a body mass index (BMI) of <35 kg/m², no complications, no postoperative limp, and better preoperative and postoperative Lower Limb Core scores. The most significant factor associated with expectation fulfillment was having a better postoperative Lower Limb Core score.

Pain Management and Accelerated Rehabilitation

Pain management has evolved into one of the leading areas of intense clinical focus in orthopaedic surgery. Mandates on patient outcome measures and surgeon performance have both driven this very important clinical initiative. The principal goals are to minimize the use of narcotic medications, to facilitate rehabilitation, to facilitate early hospital discharge, to accelerate a return to function, and to enhance patient satisfaction.

Busch et al.⁷⁰ conducted a prospective, randomized trial of sixty-two patients undergoing unilateral primary total hip arthroplasty. The patients were randomized to a protocol involving either intraoperative multimodal periarticular injection or no injection. The injection consisted of ropivacaine, ketorolac, epinephrine, and morphine. Both groups also received intravenous patient-controlled analgesia for twenty-four hours after surgery. The patients in the periarticular injection group utilized a significantly lower quantity of patient-controlled analgesia at six hours and during the first twenty-four hours after surgery (p < 0.05). The patients in the injection group also reported lower pain scores in the post-anesthesia care unit. However, there was no difference between the groups with regard to the pain score at rest. The study was underpowered to determine if the reduced patient-controlled analgesia use would have a significant impact on the reduction of opioid-related adverse effects. However, there was no difference between the groups in terms of overall patient satisfaction.

Accelerated discharge from the hospital and earlier return to function are attractive to patients. Pain management is an integral part of any such program. Dorr et al.⁷¹ prospectively evaluated sixty-nine patients who voluntarily enrolled in a comprehensive program designed for same-day discharge. The patients attended a preoperative class preparing them for this program. All total hip arthroplasties were performed with use of a posterior minimally invasive approach. Regional anesthesia was used in nearly all cases; specifically, epidural anesthesia was used for sixty-four patients, spinal anesthesia was used for four, and general anesthesia was used for one. All patients received intraoperative periarticular injection and a standard multimodal analgesia protocol previously described by the same group. Patients were discharged to home and received oral celecoxib and an oral narcotic for the treatment of pain. They also received aspirin (325 mg twice a day) for four weeks for prophylaxis against venous thromboembolism. Fifty-three patients (77%) were discharged on the same day. The patients also reported having more confidence, which further facilitated their rehabilitation progress. The three patients who were dissatisfied all had complications related to the implant. There were no cases of wound drainage, no infections, no dislocations, and no readmissions for medical complications among the fifty-three patients. Berger et al.⁷² reported on their experience with the same-day discharge protocol. One hundred and fifty patients underwent surgery with use of the two-incision minimally invasive approach. Regional anesthesia was used in all cases. The standard multimodal protocol included a COX-2 inhibitor, oxycodone, and other narcotics. Following discharge, a COX-2 inhibitor was taken for two weeks and oral narcotics were taken as needed. All 150 patients were successfully discharged on the same day. When surveyed later, six patients reported that they would have elected to stay overnight in the hospital because of nausea (five patients) or pain (one patient).

Resource Utilization

Many studies have documented greater morbidity and complication rates in association with total joint arthroplasty in obese patients. Kim⁷³ analyzed the economic impact of total joint arthroplasty in morbidly obese patients. Using the 2006 Nationwide Inpatient Sample (NIS) database, he identified 6713 total hip arthroplasties (2.9% of the total) and 20,964 total knee arthroplasties (4.2% of the total) that were performed in morbidly obese patients. Hospital cost analysis was performed with use of only unilateral cases for equitable comparison. Following adjustments for sex, age, race, and primary payer type, hospital resource utilization for total hip arthroplasty and total knee arthroplasty was 9% (mean, $1432) and 7% (mean, $1025) higher, respectively, for morbidly obese patients as compared with non-obese patients. Adjustment of hospital payments may be necessary in these cases with higher costs and complexity.

Larsen et al.⁷⁴ evaluated the comparative cost effectiveness of accelerated and standard rehabilitation protocols following total joint arthroplasty in conjunction with a prospective randomized clinical trial designed to assess any differences in terms of the length of hospital stay, the gain in health-related quality-of-life, and any adverse effects at three months after surgery. The accelerated rehabilitation protocol was effective for reducing the length of hospital stay, resulted in higher quality-of-life measures, and resulted in no added adverse effects. With the accelerated protocol, the average cost reduction was $4000 (18,880 Danish krone) in the first year after surgery. There was also a greater gain of quality-adjusted life-years (QALYs) following total hip arthroplasty with the accelerated rehabilitation protocol.

The Centers for Medicare and Medicaid Services (CMS) has sponsored a nationwide three-year trial project of pay-for-performance specifically for total joint arthroplasty: the Premier Hospital Quality Incentive Demonstration Project. Bhattacharyya et al.⁷⁵ found that the top-performance hospitals (1) specialized in orthopaedics, (2) performed a high volume of total joint arthroplasties, (3) were teaching hospitals, and (4) were located in the midwestern United States. Hospital size and revenue were not associated with increased successful outcome measures.

Policymakers have focused on the quality of and access to care. Improved quality of care has been documented at specialty hospitals in many medical and surgical disciplines. Potential concerns are that specialty hospitals will preferentially select patients with lower comorbidities and will limit access to patients whose insurance plans offer lower payments to the hospital. Lu et al.⁷⁶ examined the impact of physician-owned specialty hospitals focusing on total joint arthroplasties in three specific markets (Durham, North Carolina; Kansas City; and Oklahoma City) from 1993 to 2003. They specifically compared the specialty hospitals with competing general hospitals in terms of surgical volume and patient case complexity. The analysis mainly involved Medicare beneficiaries. The general hospitals did not experience any significant caseload reduction or an increase in case complexity.

The single largest expense related to total joint arthroplasty is the implant costs. Seventy percent of the hospital costs for total joint arthroplasty are associated with the operating room (including implants), the post-anesthesia care unit, and the inpatient hospital stay. Eighty-two percent of the costs are utilized in the first two days of the hospital stay. Scott et al.⁷⁷ reported that Medicare payments to the hospitals increased 14.9% between 1993 and 2008. The consumer price index increased 49.5%. The average implant list costs increased 204%, and the average purchasing implant costs increased 132%. There have been substantial decreases in hospital profits associated with total joint arthroplasties. Incentive programs such as gain-sharing may align surgeons and hospitals more closely. Other established strategies include implant standardization, competitive-bidding purchasing, capitated pricing, vendor discounts, and cost-awareness programs. Taylor et al.⁷⁸ evaluated the financial impact of using a capitation matrix system on total hip and total knee implant costs over one year in a community hospital system. The matrix categorized the various implants into four capitated cost levels based on implant characteristics. Pricing adjustment was based on a 15% reduction at each level from the costs of the previous fiscal year. Implant costs for the hospital decreased by 26.1% per case each for the 369 total hip arthroplasties and the 934 total knee arthroplasties. Innovative strategies must be developed to continue to meet the economic challenges of funding for total joint arthroplasties.

Access to Care

Health-care reform was one of the most important political events in 2009 as many Americans have no health insurance. Matlock et al.⁷⁹ examined the procedure rates of total joint arthroplasty with use of the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS). They specifically analyzed the primary payers of these procedures in patients between forty-five and seventy-five years of age. They found a substantial increase in the rates of total joint arthroplasty at the age of sixty-five years. This increase was similar for patients with and without insurance as many patients delayed surgery until they were eligible for Medicare benefits. The difference between the insured and the general population decreased after the age of sixty-five years. These data suggested that the uninsured patients often did not receive appropriate and indicated health care, specifically, hip and knee arthroplasty. Those patients increased their utilization of total joint arthroplasties when the financial barriers were reduced when they acquired Medicare benefits at the age of sixty-five years.

Problems remain for underinsured patients. Hinman and Bozic⁸⁰ reviewed the demographic characteristics, insurance information, and resource utilization for 224 patients who had undergone primary unilateral total hip arthroplasty. Medicaid patients were more likely to be black or Hispanic (p < 0.05) and were more likely to be single (p < 0.05) compared with the Medicare and commercial payer groups. Medicaid patients also were more likely to be smokers and had a trend toward more nonprescription drug use. There were no significant differences among the three groups in terms of narcotic use, alcohol abuse, psychiatric illness, clinical variables (BMI, American Society of Anesthesiologists [ASA] class), or operative variables (estimated blood loss, operative time, length of stay, or complications). Medicaid patients had to travel almost twice as far to receive their care (66.0 versus 38.3 miles). Medicaid patients also had significantly lower Harris hip scores both preoperatively and postoperatively (at both six months and one year). The lower functional scores for Medicaid patients may be a function of decreased access to specialty care, delayed presentation, and the resultant advanced pathology. Potential surgeon selection bias targeting Medicaid patients could not be ruled out.

Population demographics are changing. The increasing life expectancy, the increasing number of elderly patients, and the obesity epidemic will affect all aspects of health care, including total joint arthroplasty. Dunbar et al.⁸¹ examined these factors during a symposium sponsored by the American and Canadian Orthopaedic Associations. Three million individuals (1% of the population) were octogenarians in 1994. It is estimated that 5% of the population will be octogenarians by 2050. On the basis of the established correlation between age and osteoarthritis, the burden of care for total joint arthroplasty will increase substantially. Analysis of the Canadian joint registry data from 2004 to 2005 demonstrated that 87% of total knee arthroplasty patients and 74% of total hip arthroplasty patients were obese or overweight. In addition, the authors noted concerns of greater resource utilization and complications in obese patients.

There are disparities in the utilization, clinical outcome, expectations, and complications of total joint arthroplasty as a function of race and ethnicity. Lavernia et al.⁸² conducted a prospective controlled cohort study to evaluate the differences in the functional outcomes between whites and blacks undergoing total hip and knee arthroplasties. The investigators specifically assessed the influence of fear and anxiety. They administered a comprehensive list of outcome measurements, including the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), Quality of Well-Being, SF-36 (Short Form-36) General Health Score, and Pain and Anxiety Symptoms Scale (PASS), to 331 patients before and after surgery. They followed these patients for a mean of five years. Blacks reported having worse perceived general health and higher fear levels than whites before surgery. Regardless of time interval, blacks scored worse than whites on all outcome measures except for the SF-36 physical function and general health scores. These data underscored the need for addressing patient expectations and psychology through preoperative education and counseling.

Complications

Dislocation

Dislocation has been reported to be the leading cause of revision total hip arthroplasty⁸³. Proper cup position consistently has been cited as being critical for the stability of the implant, the durability of fixation, and optimum bearing surface wear. Malchau et al.⁸⁴ analyzed data from 1952 total hip arthroplasties that had been performed at a tertiary center by experienced hip surgeons. The authors defined the optimum cup position as abduction within the range of 30° to 45° and anteversion within the range of 5° to 25°. Of those, 63% were within the abduction range and 79% were within the anteversion range. Only 50% were within the range for both. Regression analysis demonstrated that surgical approach and surgeon experience were significant factors for outliers (p < 0.001 for both). The two-incision minimally invasive approach was associated with threefold greater prevalence of outliers (p = 0.001). The mini-anterolateral approach was associated with 2.5-fold greater prevalence of outliers (p = 0.035).

Hip stability and leg-length equality are critical for a satisfactory outcome following any total hip arthroplasty. Optimization of femoral offset can be accomplished with a variety of techniques. Emerson and Barrington⁸⁵ reported on the use of an offset head design to address selected patients with extreme varus and short femoral neck anatomy. This head design with a 4-mm lateralization also was used for patients undergoing revision for the treatment of instability and for patients with hip dysplasia. Twenty-nine heads were used over an eight-year period. Measurements demonstrated no leg lengthening and a hip offset that was within an average of 2 mm of the contralateral hip offset. There was no dislocation or failure at the taper junction. Another technique to optimize offset is to use a modular stem design. White et al.⁸⁶ reported restoration of desirable femoral offset in 60% of 100 consecutive total hip arthroplasties with the use of a single modular junction (head-stem neck) stem design. This rate was improved to 85% in another 100 consecutive total hip arthroplasties that were performed with the use of a dual modular junction (head-neck and neck-stem). There were no failures at the additional modular junction. Importantly, a retroverted neck was needed in 28% of the hips in order to optimize reconstructive goals. The long-term concerns are corrosion and possible breakage at the additional modular junction.

The treatment of recurrent dislocation is challenging and is associated with a high rate of failures despite modifications of surgical technique and implant design. Paprosky⁸⁷ reported the results of seventy-seven consecutive revision total hip arthroplasties that were performed for the treatment of recurrent dislocation. The mean age of the patients was sixty-eight years. The patients had had an average of two previous operations for the treatment of dislocation. The mechanism of dislocation was classified into six types: (1) cup malposition, (2) stem malposition, (3) abductor insufficiency, (4) impingement, (5) wear and head penetration, and (6) unclear etiology. The most common mechanism was type 3 (37%), followed by type 1 (33%). The surgical treatment was specific to the mechanism that was identified and consisted of component revision (types 1 and 2), insertion of a constrained liner (types 3 and 6), removal of the source of impingement and insertion of a larger head (type 4), or liner exchange (type 5). Despite this algorithm and the experiences of the surgeons at this tertiary center, redislocation occurred in twelve patients (15.6%) after a mean duration of follow-up of only 2.5 years. Seventy-five percent of these redislocations were in patients with a type-3 mechanism. Five (63%) of the eight constrained liner failures were in cases in which the liner was cemented into a preexisting shell.

Infection

Several studies focused on the diagnosis of infection at the site of total joint arthroplasty. Della Valle et al.⁸⁸ followed eighty-six patients (eighty-seven hips) who underwent a multiple-stage reimplantation protocol for the treatment of an established infection at the site of a total hip arthroplasty. Their treatment protocol included implant removal, administration of intravenous antibiotics for six weeks, cessation of antibiotics for two weeks, then reimplantation. The C-reactive protein level and the erythrocyte sedimentation rate were higher in patients with persistent infection (nine hips; 10.3%). The best predictive test was synovial fluid white blood-cell (WBC) analysis with a cutoff value of 3528 WBC/mm³ and a differential of 79% polymorphonuclear cells. Sporer et al.⁸⁹, from the same institution, reviewed the records for patients who had undergone forty-two joint arthroplasties (twenty-two total knee arthroplasties and twenty total hip arthroplasties) and were managed for an acute hematogenous infection, most commonly staphylococcal (40%) and streptococcal (37.5%) infection. The mean duration of symptoms was 5.4 days (range, one to twenty-eight days). All patients were managed with irrigation and debridement with exchange of the modular components, followed by six weeks of intravenous antibiotics and a variable course of oral suppressive therapy. The mean duration of follow-up was 4.3 years. Recurrent infection occurred in nine (21%) of the forty-two joints. There was no correlation between reinfection and the type of procedure (total knee replacement or total hip arthroplasty), age, sex, diabetes, inflammatory arthritis, revision or primary surgery, or the time to surgical debridement from the onset of symptoms. The only predictor for poor outcome was a staphylococcal infection.

Sherrell et al.⁹⁰ collected data between 1990 and 2007 on ninety-seven patients from five large tertiary referral centers for total joint arthroplasty. The selection criteria included initial treatment of a periprosthetic joint infection with debridement and irrigation and subsequent failure resulting in two-stage reimplantation. The mean duration of follow-up was 3.6 years. Twenty-nine (30%) of the ninety-seven patients became reinfected after treatment with the two-stage protocol, a result significantly worse than the reported prevalence of failure associated with a two-stage protocol without previous debridement and irrigation as determined on the basis of a literature review (average, 9%) (p = 0.0007). Multiple factors could be involved, including host immune status, the adequacy of the index debridement and irrigation procedure, organism virulence, and surgical and antibiotic protocol differences from center to center. The surgeon should counsel the patient with regard to the guarded prognosis following the treatment of periprosthetic infections with debridement and irrigation.

Hansen et al.⁹¹ studied the cost-effectiveness of work-up for fever following total joint arthroplasty. In that study, 1100 patients were reviewed over a two-year period at a tertiary teaching hospital. Fifteen percent of all of the patients were recorded to have had fever of >38.5°C. A diagnostic work-up was performed for 43% of the patients with a recorded fever. Thirty-five tests (14%) were positive. The most common positive tests were urine analysis demonstrating pyuria (23.7%) and positive urine culture (22%). Of the positive tests, 26% led to a change in clinical management. The direct costs spent on the evaluation of fever over these two years were $73,878. Regression analysis demonstrated that fever for more than three days (p = 0.001, odds ratio = 6) and multiple days of elevated temperature (p = 0.003, odds ratio = 7.3) were the most predictive of a positive work-up test. Patients with fever of >39.0°C were also found to have a higher rate of positive fever work-up tests (p = 0.005). On the basis of these data, the authors recommended initiating work-up for fever in the patients with a temperature of >39.0°C, those with multiple days of fever, and those with fever after the fourth postoperative day.

Evidence-Based Orthopaedics

Over the past year, the editorial staff of The Journal reviewed a large number of recently published research studies related to the musculoskeletal system that received a Level of Evidence grade of I. Over 100 medical journals were reviewed to identify these articles, which all have high-quality study designs. In addition to the articles already cited in this Update, four Level-I articles were identified that were relevant to total hip arthroplasty. A list of these titles is appended to this review following the standard bibliography. We have provided a brief commentary about each of the four articles to help guide your further reading, in an evidence-based fashion, in this subspecialty area.

References

Matta JM. Long term survivorship of the hip after fixation of acetabular fractures. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Swanson MA; Huo MH. Total hip arthroplasty following acetabular fracture. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Pellegrini VD Jr; Sterling R. Conversion total hip arthroplasty after acetabular fracture repair: analysis of hardware and infection. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Ries M; Hansen E. Cemented cage reconstruction for Paprosky type 3 acetabular defects in revision THA. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Gross AE; Lee PTH; Backstein D; Safir O. Long term followup results for major column acetabular allograft in revision total hip replacement. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Clohisy JC; Paxton S; Keeney J; Maloney WJ 3rd. Cementless acetabular revision for the treatment of massive pelvic osteolysis. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Kishida S; Iida S; Ohashi H; Uamazawa T; Tanabe Y. Effect of the mixture of hydroxyapatite granules into bone chips on the dynamic migration of cemented acetabular cups fixed with impaction bone grafting. Read at the Annual Meeting of the Orthopaedic Research Society; 2010 Mar 6-9; New Orleans, LA.

Markel D; Flynn J; Jackson N; Esquivel A; Tong S; Wooley P; Ren W. CD14 CD16 monocytes are associated with the pathology of aseptic loosening. Read at the Annual Meeting of the Orthopaedic Research Society; 2010 Mar 6-9; New Orleans, LA. Paper no. 0153.

Huddleston J; Uquillas C; Maloney W; Smith R. A comparative study of bone ingrowth into porous metallic materials. Read at the Annual Meeting of the Orthopaedic Research Society; 2010 Mar 6-9; New Orleans, LA. Paper no. 0154.

Bozic KJ; Pui CM; Ludeman MJ; Vail TP; Silverstein MD. Do the potential benefits of metal-on-metal hip resurfacing justify the increased cost and risk of complications?Clin Orthop Relat Res. 2010;468:2301-12.[PubMed][CrossRef]

De Smet K; Campbell PA; Gill HS. Metal-on-metal hip resurfacing: a consensus from the Advanced Hip Resurfacing Course, Ghent, June 2009. J Bone Joint Surg Br. 2010;92:335-6.[PubMed]

Randelli F; Banci L; Randelli G. Second generation metal-on-metal total hip replacements at 13-year follow-up. Presented at the Annual Meeting of the American Academy of Orthopaedic Surgeons; 2010 Mar 9-13; New Orleans, LA. Podium no. 015 .

Amstutz HC; Gruen TA; Le Duff MJ; Wisk L. Metal-on-metal hip resurfacing—the first 100 hips with a minimum 10 year follow-up. Presented at the Annual Meeting of the American Academy of Orthopaedic Surgeons; 2010 Mar 9-13; New Orleans, LA. Podium no. 671.

Bin Nasser A; Beaulé PE; O'Neill M; Kim PR; Fazekas A. Incidence of groin pain after metal-on-metal hip resurfacing. Clin Orthop Relat Res. 2010;468:392-9.[PubMed]

Fowble VA; dela Rosa MA; Schmalzried TP. A comparison of total hip resurfacing and total hip arthroplasty—patients and outcomes. Bull NYU Hosp Jt Dis. 2009;67:108-12.[PubMed]

Zywiel MG; Marker DR; McGrath MS; Delanois RE; Mont MA. Resurfacing matched to standard total hip arthroplasty by preoperative activity levels—a comparison of postoperative outcomes. Bull NYU Hosp Jt Dis. 2009;67:116-9.[PubMed]

Garbuz DS; Tanzer M; Greidanus NV; Masri BA; Duncan CP. Metal-on-metal hip resurfacing versus large-diameter head metal-on-metal total hip arthroplasty: a randomized clinical trial. Clin Orthop Relat Res. 2010;468:318-25.[PubMed]

Stulberg BN; Fitts SM; Bowen AR; Zadzilka JD. Early return to function after hip resurfacing: is it better than contemporary total hip arthroplasty?J Arthroplasty. 2010;25:748-53.[PubMed]

Hall DP; Srikantharajah D; Anakwe RE; Gaston P; Howie CR. Patient-reported outcome following metal-on-metal resurfacing of the hip and total hip replacement. Hip Int. 2009;19:245-50.

Cooke NJ; Rodgers L; Rawlings D; McCaskie AW; Holland JP. Bone density of the femoral neck following Birmingham hip resurfacing. Acta Orthop. 2009;80:660-5.[PubMed]

Banerjee M; Bouillon B; Banerjee C; Bäthis H; Lefering R; Nardini M; Schmidt J. Sports activity after total hip resurfacing. Am J Sports Med. 2010;38:1229-36.[PubMed]

Prosser GH; Yates PJ; Wood DJ; Graves SE; de Steiger RN; Miller LN. Outcome of primary resurfacing hip replacement: evaluation of risk factors for early revision. Acta Orthop. 2010;81:66-71.[PubMed]

Corten K; MacDonald SJ. Hip resurfacing data from national joint registries: what do they tell us? What do they not tell us?Clin Orthop Relat Res. 2010;468:351-7.[PubMed]

McBryde CW; Theivendran K; Thomas AM; Treacy RB; Pynsent PB. The influence of head size and sex on the outcome of Birmingham hip resurfacing. J Bone Joint Surg Am. 2010;92:105-12.[PubMed]

Jeffers JR; Roques A; Taylor A; Tuke MA. The problem with large diameter metal-on-metal acetabular cup inclination. Bull NYU Hosp Jt Dis. 2009;67:189-92.[PubMed]

De Haan R; Pattyn C; Gill HS; Murray DW; Campbell PA; De Smet K. Correlation between inclination of the acetabular component and metal ion levels in metal-on-metal hip resurfacing replacement. J Bone Joint Surg Br. 2008;90:1291-7. Erratum in: J Bone Joint Surg Br. 2009;91:700.[PubMed]

Isaac GH; Siebel T; Oakeshott RD; McLennan-Smith R; Cobb AG; Schmalzried TP; Vail TP. Changes in whole blood metal ion levels following resurfacing: serial measurements in a multi-centre study. Hip Int. 2009;19:330-7.[PubMed]

Grammatopoulos GA; Langton D; Kwon Y-M; Pandit HG; McLardy-Smith P; Gundle R; Whitwell D; Gill HS; Murray DW. The role of acetabular component positioning in the development of inflammatory pseudotumours. Presented at the Annual Meeting of the American Academy of Orthopaedic Surgeons; 2010 Mar 9-13; New Orleans, LA. Podium no. 013.

Langton DJ; Sprowson AP; Mahadeva D; Bhatnagar S; Holland JP; Nargol AV. Cup anteversion in hip resurfacing: validation of EBRA and the presentation of a simple clinical grading system. J Arthroplasty. 2010;25:607-13.[PubMed]

Langton DJ; Jameson SS; Joyce TJ; Hallab NJ; Natu S; Nargol AV. Early failure of metal-on-metal bearings in hip resurfacing and large-diameter total hip replacement: a consequence of excess wear. J Bone Joint Surg Br. 2010;92:38-46.[PubMed]

Daniel J; Ziaee H; Kamali A; Pradhan C; Band T; McMinn DJ. Ten-year results of a double-heat-treated metal-on-metal hip resurfacing. J Bone Joint Surg Br. 2010;92:20-7.[PubMed]

Ball ST; Schmalzried TP. Posterior femoroacetabular impingement (PFAI)—after hip resurfacing arthroplasty. Bull NYU Hosp Jt Dis. 2009;67:173-6.[PubMed]

Joseph J; Mullen M; McAuley A; Pillai A. Femoral neck resorption following hybrid metal-on-metal hip resurfacing arthroplasty: a radiological and biomechanical analysis. Arch Orthop Trauma Surg. 2010 Mar 6 [Epub ahead of print].

de Steiger RN; Miller LN; Prosser GH; Graves SE; Davidson DC; Stanford TE. Poor outcome of revised resurfacing hip arthroplasty. Acta Orthop. 2010;81:72-6.[PubMed]

Eswaramoorthy VK; Biant LC; Field RE. Clinical and radiological outcome of stemmed hip replacement after revision from metal-on-metal resurfacing. J Bone Joint Surg Br. 2009;91:1454-8.[PubMed]

Beckmann J; Stengel D; Tingart M; Götz J; Grifka J; Lüring C. Navigated cup implantation in hip arthroplasty. Acta Orthop. 2009;80:538-44.[PubMed]

Renkawitz T; Tingart M; Grifka J; Sendtner E; Kalteis T. Computer-assisted total hip arthroplasty: coding the next generation of navigation systems for orthopedic surgery. Expert Rev Med Devices. 2009;6:507-14.[PubMed]

Dorr LD. Optimizing hip offset in total hip arthroplasty. Read at the 2009 Summer Meeting of the Hip Society ; 2009 Sept; Palo Alto, CA.

Manzotti A; Cerveri P; De Momi E; Pullen C; Confalonieri N. Does computer-assisted surgery benefit leg length restoration in total hip replacement? Navigation versus conventional freehand. Int Orthop. 2009 Nov 11 [Epub ahead of print].

Ryan JA; Jamali AA; Bargar WL. Accuracy of computer navigation for acetabular component placement in THA. Clin Orthop Relat Res. 2010;468:169-77.[PubMed]

Schnurr C; Nessler J; Meyer C; Schild HH; Koebke J; König DP. How accurate is image-free computer navigation for hip resurfacing arthroplasty? An anatomical investigation. J Orthop Sci. 2009;14:497-504.[PubMed]

Olsen M; Davis ET; Chiu M; Gamble P; Tumia N; Boyle RA; Schemitsch EH. Imageless computer navigation without pre-operative templating may lead to malpreparation of the femoral head in hip resurfacing. J Bone Joint Surg Br. 2009;91:1281-6.[PubMed]

Antoniou J; Bergeron SG; Ma B; Chakravertty R; Rudan J. The effect of the cam deformity on the insertion of the femoral component in hip resurfacing. J Arthroplasty. 2010 Mar 25 [Epub ahead of print].

Pitto RP; Malak S; Anderson IA. Accuracy of computer-assisted navigation for femoral head resurfacing decreases in hips with abnormal anatomy. Clin Orthop Relat Res. 2009;467:2310-7.[PubMed]

Potter HG; Koff MF; Campbell G; Su EP. MRI of metal on metal surface replacements. Read at the 2010 Open Meeting of the Hip Society and AAHKS; 2010 Mar 13; New Orleans, LA.

Glyn-Jones S; Pandit H; Kwon YM; Doll H; Gill HS; Murray DW. Risk factors for inflammatory pseudotumour formation following hip resurfacing. J Bone Joint Surg Br. 2009;91:1566-74.[PubMed]

O'Neill M; Beaule PE; Bin Nasser A; Garbuz D; Lavigne M; Duncan C; Kim PR; Schemitsch E. Canadian academic experience with metal-on-metal hip resurfacing. Bull NYU Hosp Jt Dis. 2009;67:128-31.[PubMed]

Beaule PE; Smith FC; Powell JN; Antoniou J; Bourne RB; Lavigne M; Belzile E; Schemitsch EH; Garbuz DS. A survey on the incidence of pseudotumours with MOM hip resurfacings in Canadian academic centres. Read at the 2009 Summer Meeting of the Hip Society ; 2009Sept; Palo Alto, CA.

Schmalzried TP; Moradi B; Kertzner M; Dela Rosa MA. Incidence and types of local reactions associated with metal-metal bearings. Read at the 2010 Open Meeting of the Hip Society and AAHKS; 2010 Mar 13; New Orleans, LA.

Malviya A; Holland JP. Pseudotumours associated with metal-on-metal hip resurfacing: 10-year Newcastle experience. Acta Orthop Belg. 2009;75:477-83.[PubMed]

Zustin J; Amling M; Krause M; Breer S; Hahn M; Morlock MM; Rüther W; Sauter G. Intraosseous lymphocytic infiltrates after hip resurfacing arthroplasty: a histopathological study on 181 retrieved femoral remnants. Virchows Arch. 2009;454:581-8.[PubMed]

Zustin J; Krause M; Breer S; Hahn M; von Domarus C; Rüther W; Sauter G; Morlock MM; Amling M. Morphologic analysis of periprosthetic fractures after hip resurfacing arthroplasty. J Bone Joint Surg Am. 2010;92:404-10.[PubMed]

Hart A; Masters JP; Sandison A; Sabah S; Skinner J; Porter M; Muirhead-Allwood S; Cobb JP. Histological and immunohistochemical response in tissue around metal on metal hips—the UK experience. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons; 2010 Mar 9-13; New Orleans, LA. Podium no. 010.

Mahendra G; Pandit H; Kliskey K; Murray D; Gill HS; Athanasou N. Necrotic and inflammatory changes in metal-on-metal resurfacing hip arthroplasties. Acta Orthop. 2009;80:653-9.[PubMed]

Kwon YM; Thomas P; Summer B; Pandit H; Taylor A; Beard D; Murray DW; Gill HS. Lymphocyte proliferation responses in patients with pseudotumors following metal-on-metal hip resurfacing arthroplasty. J Orthop Res. 2010;28:444-50.[PubMed]

Ziaee H; Daniel J; Pradhan C; Pynsent P; McMinn DJW. Placental regulation of metal transfer in patients with metal-metal surface replacement arthroplasty. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons; 2010 Mar 9-13; New Orleans, LA. Podium no. 009.

Jacobs JJ; Novak CC. Metal ion levels in maternal and placental blood following metal-on-metal arthroplasty. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons; 2010 Mar 9-13; New Orleans, LA. Podium no. 008.

Maloney WJ 3rd; Mall NA; Nunley RM; Zhu JJ; Barrack RL; Clohisy JC. The effect of highly crosslinked polyethylene on osteolysis. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Rubash HE; Jarrett B; Jibodh S; Kandil A; Greene M; Bragdon CR; Malchau H. Low wear with large diameter femoral heads. Read at the 2010 Open Meeting of the Hip Society and AAHKS; 2010 Mar 13; New Orleans, LA.

Currier B; Currier J; Collier J; Mayor M; VanCitters D. In vivo oxidation of highly cross-linked UHMWPE bearings. Read at the Annual Meeting of the Orthopaedic Research Society; 2010 Mar 6-9; New Orleans, LA. Paper no. 0170.

Kurtz SM; Medel F; Parvizi J; Austin MS; Klein G; Hartzband M; Stulberg BN; Garino JP; Kraay MJ; Rimnac CM. Wear and material performance of 1st generation highly crosslinked polyethylene implanted up to 10 years. Read at the American Association of Hip and Knee Surgeons Annual Meeting; 2010 Nov 5-7; Dallas, TX.

Rubash HE; Muratoglu OK; Wannamae KK; Rowell SR; Micheli BR; Malchau H. Ex-vivo stability loss of highly cross linked ultra-high molecular weight polyethylene. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Harris WH; Muratoglu OK; Wannomae KK; Oral E; Ghali B; Rowell SR; Malchau H. A striking paradigm shift on understanding oxidation in ultra-high molecular weight polyethylene. Read at the Hip Society Summer Meeting; 2009 Sep; Palo Alto, CA.

Oral E; Malhi AS; Wannomae KK; Muratoglu OK. Highly cross-linked ultrahigh molecular weight polyethylene with improved fatigue resistance for total joint arthroplasty. J Arthroplasty. 2008;23:1037-44.[PubMed]

Oral E; Ghali B; Rowell SL; Micheli BR; Muratoglu O. Surface cross-linked UHMWPE: a low wear material with very high fatigue strength. Read at the American Association of Hip and Knee Surgeons Annual Meeting; 2010 Nov 5-7; Dallas, TX.

Capello WN. Ceramic on ceramic: 10 year follow-up. Read at the Hip Society Summer Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Hothan A; Huber G; Weiss C; Hoffmann N; Morlock M. Femoral stems are decisive components for the characteristics of squeaking. Read at the Annual Meeting of the Orthopaedic Research Society; 2010 Mar 6-9; New Orleans, LA.

Mancuso CA; Jout J; Salvati EA; Sculco TP. Fulfillment of patients' expectations for total hip arthroplasty. J Bone Joint Surg Am. 2009;91:2073-8.[PubMed]

Busch CA; Whitehouse MR; Shore BJ; MacDonald SJ; McCalden RW; Bourne RB. The efficacy of periarticular multimodal drug infiltration in total hip arthroplasty. Clin Orthop Relat Res. 2010;468:2152-9.[PubMed]

Dorr LD; Thomas DJ; Zhu J; Dastane M; Chao L; Long WT. Outpatient total hip arthroplasty. J Arthroplasty. 2010;25:501-6.[PubMed]

Berger RA; Sanders SA; Thill ES; Sporer SM; Della Valle C. Newer anesthesia and rehabilitation protocols enable outpatient hip replacement in selected patients. Clin Orthop Relat Res. 2009;467:1424-30.[PubMed]

Kim SH. Morbid obesity and excessive hospital resource consumption for unilateral primary hip and knee arthroplasty. J Arthroplasty. 2009 Oct 29 [Epub ahead of print].

Larsen K; Hansen TB; Thomsen PB; Christiansen T; Søballe K. Cost-effectiveness of accelerated perioperative care and rehabilitation after total hip and knee arthroplasty. J Bone Joint Surg Am. 2009;91:761-72.[PubMed]

Bhattacharyya T; Mehta P; Freiberg AA. Hospital characteristics associated with success in a pay-for-performance program in orthopaedic surgery. J Bone Joint Surg Am. 2008;90:1240-3.[PubMed]

Lu X; Hagen TP; Vaughan-Sarrazin MS; Cram P. Hospital characteristics associated with success in a pay-for-performance program in orthopaedic surgery. Clin Orthop Relat Res. 2009;467:2577-86.[PubMed]

Scott WN; Booth RE Jr; Dalury DF; Healy WL; Lonner JH. Efficiency and economics in joint arthroplasty. J Bone Joint Surg Am. 2009;91 Suppl 5:33-6.[PubMed]

Taylor B; Fankhauser RA; Fowler T. Financial impact of a capitation matrix system on total knee and total hip arthroplasty. J Arthroplasty. 2009;24:783-8.[PubMed]

Matlock D; Earnest M; Epstein A. Utilization of elective hip and knee arthroplasty by age and payer. Clin Orthop Relat Res. 2008;466:914-9.[PubMed]

Hinman A; Bozic KJ. Impact of payer type on resource utilization, outcomes and access to care in total hip arthroplasty. J Arthroplasty. 2008;23( 6 Suppl 1): 9-14.[PubMed]

Dunbar MJ; Howard A; Bogoch ER; Parvizi J; Kreder HJ. Orthopaedics in 2020: predictors of musculoskeletal need. J Bone Joint Surg Am. 2009;91:2276-86.[PubMed]

Lavernia CJ; Alcerro JC; Rossi MD. Fear in arthroplasty surgery: the role of race. Clin Orthop Relat Res. 2010;468:547-54.[PubMed]

Bozic KJ; Kurtz SM; Lau E; Ong K; Vail TP; Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009;91:128-33.[PubMed]

Malchau H; Callanan MC; Jarrett B; Bragdon CR; Zurakowski D; Freiberg AA; Rubash HE. An analysis of cup positioning in total hip arthroplasty: quality improvement by use of a local joint registry. Read at the 2010 Open Meeting of the Hip Society and AAHKS; 2010 Mar 13; New Orleans, LA.

Emerson RH; Barrington JW. Offset heads to restore femoral offset in primary total hip replacement. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

White RE Jr; Carothers JT; Cummins T; Archibeck MJ. Clinical utility of two femoral implant systems in restoration of offset and leg lengths. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Paprosky WG. An algorithmic approach to the unstable total hip arthroplasty. Read at the Hip Society Summer Closed Scientific Meeting; 2009 Sep 24-26; Palo Alto, CA.

Della Valle C; Shukla S; Ward JP; Jacofsky MC; Sporer SM; Paprosky WG. Perioperative testing for persistent sepsis following resection arthroplasty of the hip for periprosthetic infection. Read at the American Association of Hip and Knee Surgeons Annual Meeting; 2010 Nov 5-7; Dallas, TX.

Sporer SM; Dalla Valle CJ; Konigsberg B; Ting N; Burns JK; Qiu F. Acute hematogenous infection following total hip and knee arthroplasty. Read at the American Association of Hip and Knee Surgeons Annual Meeting; 2010 Nov 5-7; Dallas, TX.

Sherrell JC; Fehring TK; Springer BD; Bozic K; Hansen E; Dalla Valle C; Parvizi J; Gioe T; Zmistowski B; Odum S. The fate of two-stage reimplantation in patients treated with previous irrigation and debridement. Read at the American Association of Hip and Knee Surgeons Annual Meeting; 2010 Nov 5-7; Dallas, TX.

Hansen EN; Bozic KJ; Ward D. Cost and effectiveness of postoperative fever workup in hip and knee arthroplasty patients. Read at the American Association of Hip and Knee Surgeons Annual Meeting; 2010 Nov 5-7; Dallas, TX.

Evidence-Based Articles Related to Total Hip Arthroplasty

McCalden RW; MacDonald SJ; Rorabeck CH; Bourne RB; Chess DG; Charron KD. Wear rate of highly cross-linked polyethylene in total hip arthroplasty. A randomized controlled trial. J Bone Joint Surg Am. 2009;91:773-82.One hundred patients were enrolled into this prospective, randomized, controlled study comparing highly cross-linked and conventional polyethylene liners for total hip arthroplasty. All patients received hybrid fixation of identical components. All femoral heads were 28 mm. The cup size ranged from 48 to 58 mm. At a mean of 6.8 years after surgery, there was no difference between the groups with regard to any of the clinical outcome measures. The mean femoral head penetration rate was 0.003 mm/year for the highly cross-linked polyethylene liners, compared with 0.051 mm/year for the conventional polyethylene liners (p = 0.006). The highest wear was seen in men with conventional polyethylene liners. These data once again affirmed the superior wear rate measurements for highly cross-linked polyethylene liners at intermediate-term follow-up. Longer follow-up data are needed to conclusively validate that highly cross-linked polyethylene is more durable, particularly in high-demand patients.[PubMed][CrossRef]

Sharma V; Morgan PM; Cheng EY. Factors influencing early rehabilitation after THA: a systematic review. Clin Orthop Relat Res. 2009;467:1400-11.This meta-analysis included sixteen citations that focused specifically on the functional outcome following total hip arthroplasty. The end points included independent walking and the performance of activities of daily living. One of the most consistent findings was the efficacy of using multimodal pain management protocols. There was no difference between minimally invasive and conventional surgery if no modification in analgesia and accelerated rehabilitation were included in the program. Dislocation precautions were not necessary if the anterolateral incision was utilized during surgery. There were insufficient data to determine if such precautions are necessary following the use of the posterolateral approach. There were insufficient data to document the efficacy of a preoperative rehabilitation protocol. This study provided information to facilitate formulation of a comprehensive postoperative management protocol to optimize the functional outcome and patient satisfaction following total hip arthroplasty.[PubMed]

Eriksson BI; Kakkar AK; Turpie AG; Gent M; Bandel TJ; Hoering M; Misselwitz F; Lassen MR . Oral rivaroxaban for the prevention of symptomatic venous thromboembolism after elective hip and knee replacement. J Bone Joint Surg Br. 2009;91:636-44.Rivaroxaban, a direct Factor Xa inhibitor, is a new oral anticoagulant. This study presented the pooled analysis of the data from three phase-3 prospective, randomized, blinded clinical trials in which once-daily administration of 10 mg of rivaroxaban was compared with once-daily administration of 40 mg of enoxaparin. The study included 9581 patients. The end point was the composite of symptomatic venous thromboembolism and all-cause mortality at two weeks (0.4% compared with 0.8%; p = 0.005) and at the end of the treatment period (0.5% compared with 1.3%; p < 0.001). The incidence of major bleeding was similar for both groups (0.2%). One of the limitations of the pooled analysis was that different treatment durations were involved in the different trials. Nonetheless, newer oral antithrombotic agents may provide comparable efficacy and safety profiles as compared with existing prophylaxis options, with the potential for increased compliance with evidence-based practice guidelines due to the ease of administration and the fact that no monitoring is required.[PubMed]

Barbieri A; Vanhaecht K; Van Herck P; Sermeus W; Faggiano F; Marchisio S; Panella M. Effects of clinical pathways in the joint replacement: a meta-analysis. BMC Med. 2009;7:32.Clinical pathways have been utilized for more than two decades to reduce costs and to improve clinical outcomes. This meta-analysis included data from twenty-two studies including 6316 patients. Positive findings with clinical pathways included (1) fewer complications (risk ratio = 0.68, p = 0.04), (2) shorter length of stay (p < 0.00001), (3) more patients discharged to home (p < 0.00001), and (4) lower hospital costs (p < 0.00001). This analysis could determine which aspects of the clinical pathways were the most important in affecting clinical outcome. It is hoped that standardization of clinical pathways for joint arthroplasty will be established at the national and international level in the future with data from joint registries.[PubMed]

Topics

hip region ; hip joint ; metals ; hip replacement arthroplasty ; hip resurfacing arthroplasty

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Michael H. Huo, MD

Posted on March 19, 2011

Dr. Huo and colleagues respond to Dr. Liaw and colleagues

Professor, Orthopaedic Surgery, UT Southwestern Medical Center, Dallas, Texas

To evaluate component positioning in resurfacing, there are a myriad of different ways to position the patients, to capture x-rays (antero-posterior pelvic films, unilateral films, etc.), to utilize other imaging modalities (computer assisted scanning), and to employ various evaluative techniques (such as EBRA software). Some of these methods were mentioned in our review article, but it was not our purpose to espouse one technique as "superior" or preferred for evaluating anteversion and/or abduction angles. We commend the authors of this letter for their interest in this important topic.

Chen-Kun Liaw, MD, PhD

Posted on March 19, 2011

The Definitions Are Important For Acetabular Orientation

Orthopaedic Doctor, Chief of Orthopaedics, Tao-Yuan General Hospital , Taiwan

To the Editor:

We read the recent article, "What's New in Total Hip Arthroplasty" by Michael H. Huo et al. and we had a few comments (2010;92:2959-72).

We are concerned about the prosthetic positioning in this report. To our knowledge, the acetabular orientation consists of two components, anteversion (version) and abduction (inclination). The relevant definitions are frequently confused. Anteversion has several definitions including anatomical anteversion (true anteversion), radiographic anteversion (planar anteversion), operative anteversion, CT standardized anteversion, and Liaw's anteversion. Similarly, abduction also has a few definitions including anatomical inclination, radiographic inclination, and operative inclination. Murray clarified anatomical, radiographic, and operative definitions of anteversion and inclination and provided the mathematical relationships between these different definitions (1). CT standardized anteversion and Liaw's anteversion are other definitions to solve this positioning problem (2,3).

The authors provided us with good knowledge about clinical significance of acetabular orientation. However, the authors did not clearly mention relevant definitions of prosthetic position. According to Murray's formula, we used anatomical anteversion (30°) and inclination (35°, 55°) as a standard and calculated anteversion and inclination under other definitions (Table 1). CT standardized anteversion and Liaw's anteversion are both more complex and require more data to be calculated.

Table 1. Anteversion and inclination under different definitions, according to Murray's formula.
Definition of acetabular orientation	Anatomic anteversion 30° Anatomic inclination 35°	Anatomic anteversion 30° Anatomic inclination 55°
Radiographic anteversion	16.67°	24.18°
Radiographic inclination	31.23°	51.04°
Operative anteversion	19.30°	35.53°
Operative inclination	29.78°	45.19°

The largest difference among different definitions lies at 13.3° for anterversion (30.0° versus 16.7°) and 9.8° for inclination (abduction)(55.0° versus 45.2°), respectively. These differences should not be ignored. We therefore suggest that the authors could state the definitions used in their report explicitly so that the readers will not be confused.

References

1. Murray DW. The definition and measurement of acetabular orientation. J Bone Joint Surg Br. 1993;75:228-32.

2. Liaw CK, Yang RS, Hou SM, Wu TY, Fuh CS. A simple mathematical standardized measurement of acetabulum anteversion after total hip arthroplasty. Computat Math Meth Med. 2010;9:105-19.

3. Olivecrona H, Weidenhielm L, Olivecrona L, Beckman MO, Stark A, Noz ME, Maguire GQ Jr, Zeleznik MP, Svensson L, Jonson T. A new CT method for measuring cup orientation after total hip arthroplasty: a study of 10 patients. Acta Orthop Scand. 2004;75:252-60.

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Michael H. Huo, Kristopher G. Stockton, Michael A. Mont, Javad Parvizi; What's New in Total Hip Arthroplasty. The Journal of Bone & Joint Surgery. 2010 Dec;92(18):2959-2972.

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