It has been nearly a decade since the introduction of this Specialty Update section in The Journal. We have covered many topics that were considered to be contemporary and controversial. In the current update, we have elected to include reviews on (1) the outcomes of primary total hip arthroplasty, (2) the outcomes of revision hip arthroplasty, (3) hip resurfacing arthroplasty, (4) complications, and (5) practice management. The major new information in the past year is in epidemiology and hip resurfacing arthroplasty.
Epidemiology
Total joint arthroplasty volume is projected to continue to increase. Kurtz et al. used the Nationwide Inpatient Sample (NIS) to make projections and to analyze population-based outcomes of total joint arthroplasty. They projected that >50% of all joint arthroplasties will be performed in patients less than sixty-five years of age by 2011. Moreover, younger patients will account for 52% of all total hip arthroplasties and 55% to 62% of all primary and revision total knee arthroplasties by 2030. This projection may have implications for the private sector with regard to insurance coverage and reimbursement for joint arthroplasty procedures in the future.
Clinical Outcome
Femoral Stem
Hip resurfacing arthroplasty has become increasingly popular worldwide. One of the proposed advantages of resurfacing is that the outcome and durability are superior to those of conventional total hip arthroplasty, especially in younger patients. Springer et al. conducted a systematic review of three databases of published results of total hip arthroplasties performed with use of contemporary designs and cementless fixation in young patients. The meta-analysis included 5907 patients (6408 hips) less than fifty-five years of age. These patients were compared with 3002 patients with 3269 hip resurfacing arthroplasties. The pooled failure rate for the femoral stem was 1.3% at a mean of 8.4 years, compared with a failure rate of 2.6% at a mean of 3.9 years for the hip resurfacing arthroplasties. There were also distinct differences in the failure mechanisms for total hip arthroplasty (cup loosening and liner wear) and hip resurfacing (femoral neck fracture and femoral component loosening). At the present time, there are no evidence-based data to support a superior outcome in association with the use of hip resurfacing arthroplasty in younger patients.
Surgeons have continued to debate the differences in terms of the clinical outcome and fixation durability of proximally coated and extensively coated femoral stems. MacDonald et al. reported on a multicenter, prospective, randomized trial involving the use of either a proximally coated tapered stem (198 hips) or an extensively coated straight cylindrical stem (190 hips) after a minimum duration of follow-up of two years (mean, 6.4 years). There was no difference in any of the outcome measures (including the Harris hip score, the University of California at Los Angeles [UCLA] activity score, the Western Ontario and McMaster Universities [WOMAC] score, and the Short Form-12 [SF-12] score). There was no difference in the rate of thigh pain. The only measurable difference was in terms of bone density in zone 7 (the medial calcar region), with a 23.7% reduction in the extensively coated group and a 15.3% reduction in the proximally coated group. Stress-related bone remodeling can be modified by differing the stem design. Crowninshield et al. reported on 103 hip arthroplasties that were performed at four centers with use of a low-modulus femoral stem. The overall stem survival rate was 92% at a mean of ten years. No stem revision had been done in any of the eighty-eight patients who were living at the time of latest follow-up. The authors did not provide bone density measurement data.
Acetabular Cup
Porous-coated hemispherical acetabular cups inserted without cement have been associated with excellent success; the principal limitation has been bearing surface wear. Della Valle et al.1 reported the result of a minimum twenty-year follow-up study of 124 cups. The mean age at the time of surgery was fifty-two years. Only one cup had been revised because of loosening at twenty years. Liner revision because of wear and osteolysis was necessary in 7% of the hips. The survival rate with loosening or revision for loosening as the end point was 96% at twenty years. These data should serve as the benchmark against which to measure newer designs with different geometry, surface texture, and biomaterials.
Surgical technique may influence the success and durability of cementless cup fixation. Alexander et al. evaluated the effect of reaming on the immediate stability of cups inserted with use of a press-fit technique. This laboratory study included the use of a titanium-alloy hemispherical 55-mm acetabular shell with a plasma-spray surface texture. The standard selected was 1 mm of under-reaming of the acetabulum. Cyclic loading was performed with use of a 4000-N force until failure by spin-out. Fixation strength was measured when there was 200 µm of interface motion. There was a 16% reduction of fixation strength with only 0.25 mm of excessive reaming. This reduction increased to 56% with 0.75 mm of excessive reaming. These data underscore the importance of precision in terms of reamer size and surgical technique and raise the question of whether navigation and refinement in instrumentation could enhance the reproducibility of bone preparation and initial cup stability.
Several new studies have evaluated the fixation potential of the new generation of titanium implants (titanium foam or cancellous titanium). Jamieson et al. used a surrogate model of the acetabulum, fabricated from a composite construction of low-density polyurethane foam with rigid polymeric reinforcement. Three cups with different surface textures were tested in the laboratory. Forged hemispherical titanium-alloy (Ti-6Al-4V) shells were coated with one of three coatings: (1) "cancellous" metal, (2) conventional plasma-spray coating, and (3) a beaded texture. The fixation of the shells with the "cancellous" metal coating was found to be superior to that of conventional plasma-sprayed or beaded components when permanent interface displacement, resistance to ultimate spin-out, or a minimum fixation threshold (400 N) were compared.
Bearing Surface
Bozic et al. characterized the epidemiology of bearing surface usage with use of the NIS database in a study of 112,094 primary total hip arthroplasties performed between October 2005 and December 2006. The most commonly used coupling was metal-on-polyethylene (51%). A hard-on-hard metal-on-metal or ceramic-on-ceramic bearing coupling was used in 35% and 14% of the hips, respectively. The majority of the hard-on-hard bearing couplings were used in younger patients. However, 40% of the metal-on-metal bearing couplings and 21% of the ceramic-on-ceramic bearing couplings were reported in patients over the age of sixty-five years. Wide variations in geographic region and practice type were found with regard to bearing coupling selection.
Highly cross-linked polyethylene has been used as a bearing surface for nearly a decade. Bragdon et al. reported the seven to nine-year clinical results of 224 hip arthroplasties performed with use of a first-generation highly cross-linked polyethylene liner in a modular shell. Several head diameters were used, depending on the shell size. No cup had been revised because of loosening, and no hip had any radiographic evidence of loosening. Importantly, head penetration did not appear to increase with time. The mean wear rate was 0.02 ± 0.06 mm/yr. There were no osteolytic lesions in either the pelvis or the femur. Controversies exist with regard to the best manufacturing method for highly cross-linked polyethylene. In particular, some have questioned the wear characteristics of polyethylene that is annealed below melting temperature. D'Antonio et al. followed >300 hip arthroplasties with annealed highly cross-linked polyethylene for as long as ten years. The linear wear rate was 0.04 mm/yr during the first five years of in situ use and later decreased to 0.02 mm/yr during the second five years. These rates were similar to the wear rates reported with other types of highly cross-linked polyethylene. McCalden et al.2 prospectively followed 100 total hip arthroplasties (100 patients) for a minimum of five years. All patients received identical implants and cementless fixation. The patients were randomized to treatment with either a conventional polyethylene liner or a highly cross-linked polyethylene liner with an identical shell design and locking mechanism. All femoral heads were 28 mm. Steady-state head penetration was significantly lower in the group managed with highly cross-linked polyethylene (0.003 compared with 0.051 mm/yr; p = 0.006). Men with conventional polyethylene had the highest head penetration rate (0.081 mm/yr). This rate was significantly higher than that for either men or women with highly cross-linked polyethylene (p = 0.025). On the basis of the available data, we believe that the intermediate-term wear characteristics of highly cross-linked polyethylene are consistently superior to those of conventional polyethylene without catastrophic failures related to the altered biomechanical properties of the material.
Newer methods to reduce oxidation of highly cross-linked polyethylene are being introduced. Current methods include (1) post-irradiation remelting to quench residual free radicals and (2) addition of antioxidants such as tocopherol (vitamin E) to polyethylene powder prior to consolidation into a solid state to improve the resistance to oxidation. One concern with tocopherol is the potential tendency for it to migrate out of the polyethylene matrix during storage and under loading conditions. King et al. demonstrated excellent prevention of oxidation in gamma-irradiated polyethylene without employing the remelting process to quench the free radicals by using hindered phenol antioxidants. This gamma-irradiated and hindered phenol antioxidant-stabilized polyethylene provided better tensile strength and fatigue crack resistance relative to the gamma-irradiated but remelted polyethylene. The susceptibility of highly cross-linked polyethylene to crack propagation and failure continues to raise some concerns. Furmanski et al. found that a notch root radius of 0.13 mm was sufficient to initiate and propagate a crack under an applied static load almost immediately in moderately and highly cross-linked polyethylene. This implies that highly cross-linked polyethylene acts more like a brittle material such as ceramic rather than like a ductile metal.
Acoustic noise around total hip arthroplasties has been reported in association with all bearing couplings. It is especially of clinical relevance with ceramic-on-ceramic bearings. While the exact etiology is not yet fully defined, implant design features have been cited as a potential contributing factor. Masonis et al. evaluated 256 total hip arthroplasties with two different cup shell designs with identical ceramic biomaterial quality: eighty-one procedures were performed with the Trident design (Stryker, Mahwah, New Jersey), and 175 procedures were performed with the REFLECTION design (Smith and Nephew, Memphis, Tennessee). The mean duration of follow-up was longer for the Trident group (four years compared with 2.2 years). The prevalence of any acoustic noise was 28% in the Trident group and 5.2% in the REFLECTION group (p < 0.001). Stepwise regression analysis demonstrated no correlation with cup size, head size, leg length, or cup position angle. The only tested factor that was predictive of noise was the cup design (p = 0.002). Mai et al. evaluated the prevalence of acoustic noise in a study of 320 hips with a ceramic-on-ceramic coupling at a mean of 3.9 years. Twenty percent of the patients reported some type of noise, and 10% of the patients (thirty-two hips) reported "squeaking." Three of these hips were symptomatic, and one had been treated with revision surgery. Currier et al. demonstrated that squeaking could be reproduced in the laboratory with use of components from clinical retrievals and components that had never been implanted. Instrumentation of the explanted ceramic components with accelerometers confirmed that the vibrational frequencies of the ceramic components themselves matched the audible squeaking in vivo. On the basis of these findings, the investigators suggested that the ceramic components themselves are the source of squeaking and postulated that previously implicated etiological factors such as edge loading and stripe wear may not be as important as once believed.
Minimal Incision Surgery
There has been a reduction in the clinical enthusiasm for minimal incision surgery. Some of the reasons include (1) a difficult learning curve, (2) no documented clinical superiority beyond the short term, and (3) a potential for more complications. New data have focused on the comparison of various surgical approaches and the clinical outcome following minimal incision total hip arthroplasty.
The direct anterior approach has received much attention. Woolson et al. compared the clinical experience of five community-based surgeons who had performed 247 consecutive total hip arthroplasties with use of the anterior minimal incision approach. Their data were compared with the reported data from the innovator of this operation. The community surgeons had twofold increases in terms of operating time, estimated blood loss, and the rate of major complications (8%). The risk of a major complication decreased with increasing clinical experience after thirty to fifty procedures. A few recent studies have compared minimally invasive approaches with standard approaches. Nakata et al. randomized 195 hips to total hip arthroplasty with use of one of two minimal incision techniques: direct anterior (ninety-nine hips) and mini-posterior (ninety-six hips). The results suggested a more rapid recovery in terms of hip function and gait in association with the direct anterior approach. Chen et al. compared the two-incision approach with a conventional transgluteal approach in a study of 166 hips. The Harris hip scores were higher for the two-incision group at three and six months of follow-up. However, there was more blood loss and a longer operating time in the two-incision group. Knahr et al. randomized forty patients to treatment with either a minimal Watson-Jones approach or a conventional transgluteal approach. Gait analysis demonstrated no significant differences in temporal-spatial variables or kinematics between the two groups at any time from ten days to twelve weeks after surgery. Lee and Bernasek randomized ninety-two patients to treatment with either a mini-anterolateral approach or the conventional direct lateral approach. There were no differences between the groups in terms of operating time, blood loss, length of hospital stay, or limp. Proximal femoral fractures were more frequent in the minimal incision group. Wall and Mears3 conducted an excellent review of published studies of minimal incision total hip arthroplasty. Their systematic review demonstrated that among all of the various surgical techniques, the mini-posterior approach was studied the most and was the only approach with good-quality evidence based on randomized control studies.
Computer Navigation
Gofton et al.4 assessed the effect of using computer-assisted techniques on the learning of surgical skills by trainees. Forty-five participants were randomized to one of three training groups to learn the surgical techniques of total hip arthroplasty. Outcomes were assessed in a pretest session and in ten-minute and six-week retention and transfer tests. All groups demonstrated improved accuracy and precision in the determination of the abduction angle and the anteversion of the acetabular cups during training (p < 0.001). No significant deterioration in performance was observed between the immediate testing and the delayed testing for any of the groups. At the present time, computer navigation has been demonstrated to improve the consistency of cup positioning in total hip arthroplasty. Computer navigation may be of particular value for training surgeons to reach technical proficiency in difficult operations such as minimal incision techniques and hip resurfacing arthroplasty. It is hoped that with more precision in component placement, a reduction in the rate of complications can be realized.
Epidemiology
Bozic et al.5 analyzed the epidemiology of revision total hip arthroplasty with use of the NIS. The data on 51,345 revision procedures performed between October 2005 and December 2006 were analyzed. The most common procedure was revision of all components. The most common reasons for revision were instability (22.5%), loss of fixation (19.7%), and infection (14.8%). Revision surgery was most commonly performed in large, urban, nonteaching hospitals for Medicare patients. The mean length of hospital stay was 6.2 days. The mean total charges were $54,553. However, there were large variations in the length of stay and the costs across different regions in the country. Revision surgery was associated with much higher complication rates than primary joint arthroplasty was. Ong et al. analyzed 39,410 primary and 7411 revision total hip arthroplasties. The 180-day reoperation risk in 2006 was 1.6% for primary total hip arthroplasties and 36.6% for revision total hip arthroplasties. The infection risk was 1.3% for primary surgery and 13.9% for revision surgery. Patients managed with revision total hip arthroplasty also had greater rates of mortality (1.6 times), dislocation (8.5 times), infection (9.6 times), subsequent revision (34.5 times), and mechanical complications (74.9 times) than did patients managed with primary arthroplasty (p < 0.05 for all comparisons). These findings clearly underscore the complexity and extensive resource utilization of revision total hip arthroplasty as well as the need to optimize the perioperative care of patients undergoing this procedure.
Acetabular Revision
One of the important advances in revision total hip arthroplasty has been the introduction of cup designs and metallic augments made from alternative biomaterials such as tantalum and other so-called cancellous metal. More than five years of clinical experience with these newer designs and surgical techniques have been reported from several centers. Jafari et al. reported on an extensive experience with 528 cup revisions over 6.5 years. One hundred and forty-three procedures were performed with the tantalum design, and 385 were performed with titanium-alloy designs. The mean age was younger in the tantalum group (sixty-six compared with seventy-two years). All patients were followed for two to five years. There was no difference in the rate of utilization of bone graft (20% compared with 16%). While there was no difference in the rate of cup re-revision (3.4% for tantalum compared with 3.1% for titanium), radiographic evaluation demonstrated more consistent and predictable bone-stabilization of the shells in the tantalum group. This was especially important because tantalum cups were used in the more complex cases. Lachiewicz and Soileau reported the two to five-year results of thirty-seven acetabular revisions performed with use of the tantalum cup to treat primarily Paprosky type-2 and 3 bone deficiencies. A cemented liner was used in twelve hips, and a modular liner was used in twenty-five hips. Augments were used in four hips. Thirty-six cups (97%) remained well fixed at a mean of 2.5 years. One cup required re-revision to a larger tantalum cup because of aseptic loosening. Six additional operations were necessary: three because of recurrent dislocations, two because of infections, and one because of a distal femoral fracture. Kosashvili et al. used a tantalum cup to salvage a failed pelvic reinforcement cage in fourteen patients. These were challenging reconstructions. After a mean duration of follow-up of 3.8 years, twelve of the fourteen cups remained stable. The authors recommended cautious optimism with regard to the fixation durability of tantalum cups implanted against large areas of allograft bone from previous surgery.
The clinical results of revisions performed with cups made from newer biomaterials should be compared with those of revisions performed with conventional porous-coated cups. Wysocki et al. followed 166 cup revisions for a minimum of five years (mean, 8.6 years). The cup was a third-generation titanium-alloy hemispherical design with a fiber-mesh surface texture. Eleven cups (7%) required repeat revision surgery. Four of these procedures were performed because of loosening. Seven additional cups were definitely loose according to radiographic criteria, and pelvic osteolysis was observed in 10% of the hips. The survival estimate was 92.5% at eight years when both revision and radiographic evidence of loosening were used as end points. Reese et al. reported on sixty-two complex acetabular revisions performed with use of posterior column plating and a cementless cup for the treatment of pelvic discontinuity. These procedures represented only 0.6% of all revision total hip arthroplasties in the joint registry at their institution. After a mean duration of follow-up of 3.7 years, healing of the pelvic discontinuity had occurred in only 68% of the hips and stable cup fixation was evident in 84%. Stable cup fixation was evident in eleven of the sixteen hips with nonunion of the discontinuity. However, the clinical outcome was relatively poor, with the mean Harris hip score being 74 at the time of follow-up.
Instability is among the most common complications following revision total hip arthroplasty. Many surgeons have utilized constrained liners in the hope of reducing this complication. The use of constrained liners in patients with severe pelvic bone deficiency may result in early cup fixation failure due to the greater forces being applied to the cup-pelvis interface. Paprosky reported on eighty-three cup revisions in hips with Paprosky type-3B pelvic bone deficiencies. Eight (22%) of the thirty-six cups with constrained liners required early repeat revision because of loss of fixation. In contrast, two (4.3%) of the forty-seven cups with a large-diameter head and without a constrained liner required repeat revision. The author therefore recommended avoiding a constrained liner when treating severe pelvic bone deficiencies. If there is recurrent dislocation, one can revise to a constrained device once stable osseous ingrowth of the cup has occurred.
The clinical outcome of isolated one-component revision has been reported to be more unpredictable. Iorio et al. reported on forty-two consecutive isolated acetabular revisions that were performed by a single surgeon. Reasons for revision included loosening (76%), osteolysis (14%), and instability (10%). Bone deficiency was classified as Paprosky type 1 in 36% of the hips, type 2 in 52%, and type 3 in 12%. After a mean duration of follow-up of 6.4 years, there was significant improvement in the Harris hip score and the visual analog pain score (p < 0.001 for both), but the improvements were less in obese patients. Five hips required reoperation. Three cups required repeat revision because of loosening, and cup migration was evident in three additional hips. Importantly, no dislocations occurred.
Hip resurfacing arthroplasty has continued to gain popularity as an alternative to conventional total hip arthroplasty in selected patients. It has continued to receive tremendous exposure through direct-to-patient marketing, numerous Internet web sites, manufacturer publicity, and articles in the lay press. The surgeon must have extensive training and clinical experience in order to achieve technical proficiency in this operation. The complication rates are greater than those associated with conventional total hip arthroplasties. Many of the complications are attributable to technical shortcomings and poor patient selection6,7. There have also been reports of adverse effects of exposure to metal ions from the bearing surfaces8-10.
Clinical Outcome
The worldwide collective clinical experience has demonstrated two major conclusions. First, with regard to patient selection, more frequent complications have been reported in patients older than fifty-five years of age and in women. Second, in terms of technical proficiency, higher complication rates have been correlated with technical deficiency on the part of the surgeon.
There are now clinical outcome data at ten years after hip resurfacing arthroplasty. McMinn et al. reported on 124 consecutive procedures that were performed by a single senior surgeon. The mean duration of follow-up was 10.6 years, and the mean age of the patients was 52.8 years. Seven revisions were necessary: four because of femoral head bone collapse, two because of infections, and one because of femoral neck fracture. The cumulative ten-year survival rate was estimated to be 94%. In addition, five hips showed periprosthetic osteolysis and four showed femoral neck thinning. Amstutz et al.11 reported on the largest experience in the United States. The series included 1000 hip resurfacing arthroplasties in 838 patients who were followed for a mean of 5.6 years. The authors reported no acetabular component loosening. Ten hips were revised because of femoral neck fracture, twenty were revised because of femoral loosening, two were revised because of infection, and one was revised because of recurrent subluxation. The five-year survival rate was 95.2%, with no failures in hips treated since 2002.
Investigators from several centers have reported data comparing the outcomes of hip resurfacing with those of conventional total hip arthroplasty. Pattyn and De Smet12 compared the clinical results of 250 hip resurfacing arthroplasties with those of 190 conventional total hip arthroplasties performed with a ceramic-on-ceramic coupling. After three to six years of follow-up, the mean Harris hip scores for the two groups were nearly identical. The percentage of patients who reported engaging in high-demand activities was greater in the resurfacing group than in the conventional total hip arthroplasty group (61% compared with 30%). Graves et al. reported results from the Australian Joint Replacement Registry that included data on 10,624 hip arthroplasties. The authors reported a higher revision rate after seven years of follow-up in patients with osteoarthritis who had been managed with hip resurfacing as compared with those who had been managed with conventional total hip arthroplasty (4.6% compared with 3.4%; adjusted odds ratio, 1.42; p < 0.001). Factors associated with higher revision rates included femoral head osteonecrosis, hip dysplasia, inflammatory arthritis, female sex, increased age, a small (<50-mm) femoral component, and specific implant designs. The most common reason for revision in the first year after surgery, accounting for more than half of the early revisions, was a femoral neck fracture.
Special Patient Populations
Femoral head osteonecrosis has been recognized as one of the potential contraindications to hip resurfacing arthroplasty. Amstutz et al., in a study of eighty-four hip resurfacing arthroplasties that were performed because of femoral head osteonecrosis, reported a five-year survival rate of 97.1%. However, they emphasized that optimum bone preparation was critical for durable success. Akbar et al.13 reviewed sixty hip resurfacing arthroplasties in patients with femoral head osteonecrosis at a mean of 4.8 years. The estimated five-year survival rate was 92%.
Hip dysplasia most often affects younger patients. Controversies remain with regard to whether hip resurfacing can be safely and effectively utilized for these patients. Li et al.14 conducted a matched comparison between hip resurfacing and conventional total hip arthroplasty in patients with low-grade hip dysplasia. There were twenty-six hips in each group. No major complications occurred in either group. There was no difference in terms of the Harris hip score. However, the mean range of motion was somewhat better in the hip resurfacing group. Amstutz et al.15 reported on 103 hip resurfacing arthroplasties in ninety patients with low-grade hip dysplasia. Seven hips that were treated with early-generation femoral component fixation techniques failed, compared with only one hip that was treated with use of contemporary fixation techniques. This finding clearly underscores the importance of surgical technique in hip resurfacing arthroplasty. McBryde et al.16 reported on ninety-six hip resurfacing arthroplasties in eighty-five patients with hip dysplasia and a matched group of ninety-six hip resurfacing arthroplasties in patients with osteoarthritis without dysplasia. The dysplasia group was followed for a mean of 4.4 years, and the osteoarthritis group was followed for a mean of 4.5 years. There were five revisions in the dysplasia group: four because of acetabular loosening and one because of femoral neck fracture. There were no revisions in the osteoarthritis group. The five-year survival rate was 96.7% for the dysplasia group and 100% for the osteoarthritis group. There was no significant difference between the two groups in terms of the median Oxford hip score at any time during the study. The authors were encouraged by the intermediate-term results of hip resurfacing in patients with hip dysplasia. Improvement in acetabular component fixation may further enhance the clinical success in these challenging patients.
Functional Outcome
Several studies were conducted to compare patient functional outcomes following hip resurfacing and conventional total hip arthroplasty. Hariri et al. reported the results of a prospective, nonrandomized study of seventeen hip resurfacing and ten conventional total hip arthroplasties in patients younger than sixty-five years of age. There was no difference between the groups on the basis of many outcome measure instruments, with the exception of the UCLA activity score. There was less improvement of this activity score in the hip resurfacing group. In contrast, Lingard et al. reported superior functional outcomes following hip resurfacing (132 hips) as compared with conventional total hip arthroplasty (214 hips). There were no preoperative differences between the two groups in terms of the outcome measures. Patients in the hip resurfacing group reported better WOMAC pain scores and better scores in all domains of the SF-36 after adjustment for age, sex, and comorbidities. It remains to be determined whether some of these differences in the functional parameters can be sustained over time. Another question is whether similar functional outcomes can be achieved by using larger femoral heads for conventional total hip arthroplasties.
Patient expectations before surgery can influence postoperative outcome measures. Marker et al. followed sixty-two patients (sixty-nine hip resurfacing arthroplasties) prospectively for a minimum of three years. The investigators evaluated patient-directed outcome measures and objective measures such as the UCLA activity score before and after surgery. There was a discrepancy between the patient-expected UCLA activity score (9.1) and the actual postoperative activity score (7.4) (p < 0.0001). Sixty-three percent of the patients failed to reach their preoperative expected activity levels. Moreover, there was a correlation between the Harris hip score and failure to reach the expected activity score (r = 0.449, p < 0.0001). Newman et al.17 reported a mean UCLA activity score of >7 in a study of 126 patients who had been managed with hip resurfacing arthroplasty. However, 25% of the patients were not satisfied with the outcome because of persistent pain, limited hip flexion, decreased strength and endurance, restricted walking distance, and overall functional limitations. Additional studies are under way to evaluate if alternative rehabilitation protocols should be instituted for patients after hip resurfacing in contrast to the established protocols used for conventional total hip arthroplasty.
Surgical Techniques of Hip Resurfacing Arthroplasty
Complication rates associated with hip resurfacing arthroplasty are a function of surgeon technical proficiency. Barrack et al. specifically reviewed the clinical experiences of five high-volume surgeons who performed 623 consecutive hip resurfacing arthroplasties over eighteen months. There were only two cases each of femoral neck fracture and dislocation. Varus malpositioning of the femoral component occurred in 15.1% of the hips. Cup positioning exceeding 50° of abduction was evident in 8.9% of the hips. There was improvement in component positioning as the learning curve progressed; however, component malpositioning was still present in 7% to 15% of the final twenty-five hips treated by each of the five surgeons. This finding underscores the importance of the need for further improvements in instrumentation. In addition, the utility of computer navigation should also be further investigated.
Moonot et al.18 quantified acetabular bone stock preservation in patients managed with hip resurfacing arthroplasty. They reviewed the implant records for 700 conventional total hip arthroplasties and compared them with those for 500 hip resurfacing arthroplasties. For age-matched women the mean outside diameter of the hip resurfacing acetabular cup was 2.03 mm less than that used for conventional total hip arthroplasty (p < 0.0001), whereas for men there was no significant difference. On the basis of these data, the amount of acetabular bone removed is similar in hip resurfacing and conventional total hip arthroplasties.
Some recognized technical challenges associated with hip resurfacing arthroplasty include failure to reestablish femoral offset, excessive femoral neck anteversion, and an unfavorable head-neck ratio, all of which can lead to impingement. Techniques that have been utilized to maximize restoration of the head-neck ratio include appropriate femoral component positioning, femoral neck osteoplasty, and increasing femoral component head size. The small head-neck ratio is of concern. Kluess et al.19 developed a three-dimensional computer model to simulate range of motion with different implant designs. They found less range of motion when hip resurfacing was compared with a conventional stemmed total hip femoral component. None of the resurfacing designs that were tested provided flexion of >90° without impingement. This raises concern regarding impingement of the femoral neck on the acetabular component, which may lead to an increased risk for femoral neck fracture, dislocation, and/or fixation loosening. On rare occasions, femoral neck-acetabulum impingement can cause pain. Lavigne et al.20 performed a femoral neck osteoplasty to minimize osseous impingement following hip resurfacing arthroplasty. This operation is associated with the risks of femoral neck fracture and osteonecrosis.
Navigation may be especially useful for surgeon training and for enhancing reproducible component positioning during surgery. Olsen et al.21 used imageless navigation for 100 hip resurfacing arthroplasties. The stem-shaft angle differed from the preoperative plan by a mean of 2.8°, and the angle fell within 5° of the planned position in 86% of the cases. There were no instances of femoral neck notching or varus component positioning. In the study by Ganapathi et al.22, fifty-one consecutive hip resurfacing arthroplasties that had been performed with use of imageless navigation were compared with eighty-eight consecutive resurfacing arthroplasties that had been performed without navigation. The stem-shaft angle did not exceed the preoperative plan by >5° in any of the hips that were treated with navigation, whereas the angle exceeded the preoperative plan by >5° in 38% of the hips that had been treated without navigation. There was no case of femoral neck notching in the group treated with navigation, but there were four such cases in the group treated without navigation. The authors concluded that imageless navigation decreased the risk of suboptimal implant positioning. Bailey et al.23 used a patient-specific computer model of the proximal part of the femur to determine the ideal femoral component position preoperatively. The targeted femoral component position in the coronal plane was reproduced in nearly all of the thirty-seven hip resurfacing arthroplasties. In summary, navigation improves component positioning accuracy, and thus its use should reduce complications and enhance clinical outcomes. Questions remain whether optimization of femoral component positioning is worth the extra expense, operating time, and learning curve involved with navigation.
Complications
Patient selection is of critical importance in avoiding complications. Mangelson created a prediction model on the basis of data from the Australian Hip Resurfacing Registry. When inexperienced surgeons were paired with patients with high risk factors, the predicted failure rate was threefold higher than the predicted failure rate when experienced surgeons were paired with patients with few risk factors (8.9% compared with 3.1%). The predicted failure rate was only 1.7% when inexperienced surgeons were paired with patients with few risk factors. Jameson et al.24 assessed the influence of age and sex on implant survival and functional outcome. In that study, 100 hip resurfacing arthroplasties in women were compared with 100 procedures in men after comparable durations of follow-up. Femoral neck fractures occurred in 3% of the women and 1.3% of the men. The authors concluded that modifications in patient selection and surgical technique may minimize the risk of fracture.
Femoral neck fracture remains the most common complication following hip resurfacing arthroplasty. Morlock et al.25 analyzed a large collection of 267 failed hip resurfacing procedures. Most failures occurred during the surgeon's first fifty to 100 operations. The authors found that early failures on the femoral side usually occurred within the first nine months after surgery and were most directly related to the surgical technique or patient selection. Late failures were mainly due to acetabular wear or loss of fixation.
Groin pain has been reported following hip resurfacing arthroplasty. Nasser et al. evaluated the prevalence of groin pain after 116 hip resurfacing arthroplasties. After a mean duration of follow-up of 1.5 years, 21.6% of the patients reported groin pain, 11.2% reported the need for analgesic medications, and 10.3% reported activity limitation due to the pain. There was an increased risk of groin pain in patients with impingement and in women. The groin pain resolved in eight of the thirteen patients who needed analgesics by eighteen months. The origin of this clinical entity remains undefined.
Metal Ions
Concerns about metal ion levels have been raised not only for hip resurfacing but for all hip arthroplasties performed with metal-on-metal couplings. At the present time, epidemiology studies have not confirmed any increased risk of neoplasia in patients with metal-on-metal couplings; however, local-tissue inflammatory responses resulting from bearing surface wear have been documented. Some investigators have suggested that a high cup-abduction angle (>45°) and excessive anteversion (>30°) are risk factors for increased wear and ion release. In addition, metal hypersensitivity can lead to lymphocytic responses in patients without evidence of wear. Clinical manifestations include joint effusion with or without an adjacent mass (pseudotumor). The prevalence has been reported to range from <0.1% to 1% in large clinical series.
De Haan et al.26 reported metal ion measurements for 214 patients managed with hip resurfacing arthroplasties. The authors found that acetabular cups with abduction of >55° were associated with elevated cobalt and chromium levels. This finding was especially pronounced in association with smaller femoral components. The authors hypothesized that this could be due to greater edge-loading of the components. Hart et al.27 measured whole-blood metal ion levels in twenty-six patients with well-functioning hip resurfacing arthroplasties and a mean Harris hip score of 94 after a mean duration of follow-up of twenty-one months. The authors identified the threshold cup abduction angle to be 50°. Below that cup angle, the mean whole-blood cobalt and chromium levels were 1.6 ppb and 1.88 ppb, respectively. With a cup angle above this threshold, the mean cobalt and chromium levels were 4.45 ppb (p < 0.01) and 4.3 ppb (p = 0.01), respectively. At one year after surgery, the metal levels in fourteen patients did not show an appreciable change from earlier testing. Other investigators had previously established that cobalt and chromium ions have the potential to induce oxidative stress through irreversible biochemical damage to macromolecules. Daniel et al.9 performed a prospective study of twenty-six men with unilateral hip resurfacing arthroplasties. Metal ion levels were documented over six years. The data demonstrated an early increase in the twenty-four-hour urinary excretion of metal ions, reaching a peak level at six months after surgery for cobalt and at one year for chromium. Subsequently, there was a decrease in the excretion of both cobalt and chromium. The metal ion levels in whole blood also showed an increase at one year, followed by a decreasing trend through the sixth year. In summary, blood metal ion levels are elevated in association with all metal-on-metal couplings. They appear to remain elevated for as long as six years after hip resurfacing arthroplasty. Patients with excessive metal ion levels appear to have suboptimal component position.
Pandit et al.10 reported twenty cases of pseudotumor in seventeen patients following hip resurfacing arthroplasty. This entity has been called ALVAL (aseptic lymphocytic vasculitis-associated lesions) and appears to be associated with metal hypersensitivity following hip resurfacing arthroplasty. In that series, all patients were women and there was a high prevalence of hip dysplasia. Histologically, the pseudotumor was characterized by extensive necrosis and lymphocytic infiltration. The authors estimated that this condition may develop in approximately 1% of patients managed with hip resurfacing arthroplasty. Kwon et al. followed ninety-seven hip resurfacing arthroplasties in seventy-one patients for a mean of six years. The authors identified pseudotumors in 8% of the patients with use of ultrasound or magnetic resonance imaging scans. Five of the patients were women. These patients had higher serum cobalt levels as compared with the levels in patients without a pseudotumor. Additional work is needed to delineate the etiology, natural history, and best treatment for this problem.
In the study by McGrath et al.28, thirty-nine hips that were treated with revision total hip arthroplasty following a failed hip resurfacing procedure were compared with a matched group of hips treated with primary total hip arthroplasty. There was no difference between the groups in terms of perioperative parameters, with the exception of a longer operating time in the conversion group, and there was no difference in terms of clinical outcomes at a mean of forty-five months. The authors had greater difficulty in association with revision procedures performed because of pseudotumor in contrast with more routine revisions. Grammatopoulos et al. reviewed their experience with fifty-four revisions that were performed following a failed hip resurfacing arthroplasty. The authors analyzed the outcome on the basis of the etiology for the revision. They also compared these hips with a matched series of hips treated with primary total hip arthroplasty. Their data demonstrated that (1) there were more complications after revision of a hip resurfacing arthroplasty than after routine primary total hip arthroplasty and that (2) the functional outcomes of revisions performed for the treatment of a pseudotumor were worse than those of revisions performed for other reasons.
Femoral Neck Narrowing
Femoral neck narrowing after hip resurfacing arthroplasty has been reported. Spencer et al.29 reviewed forty hip resurfacing arthroplasties in thirty-six patients and observed femoral neck narrowing in 90% of the hips at two years. Further progression of the narrowing was not observed for as long as seven years after surgery. The exact etiology of this finding is not yet defined. Potential causes include stress-related bone remodeling and osteonecrosis under the femoral component.
In summary, hip resurfacing arthroplasty is a reasonable alternative to conventional total hip arthroplasty in selected patients. Complications occur more frequently, and some of the complications remain to be fully characterized with regard to etiology, frequency of occurrence, natural history, and optimal treatment protocols.
Thromboembolism
Prophylaxis against venous thromboembolism has been mandated by the government, payers, and patient groups. Controversies remain with regard to the ideal agent, timing and duration of administration. The American Association of Hip and Knee Surgeons (AAHKS) comprises >800 joint arthroplasty subspecialists. Markel et al. reported the results of a membership survey, conducted in 2008, regarding thromboembolic prophylaxis. The response rate was 55.4% (465 surgeons). More than 80% of the respondents reported using a risk-stratification strategy for selecting prophylaxis. More than 90% prescribed both chemoprophylaxis and mechanical prophylaxis. Fewer than 10% reported using routine screening for the detection of asymptomatic deep-vein thrombosis. Slightly more than half reported having made changes in their prophylaxis regimen in the previous five years, and 28.3% made the changes on the basis of the guidelines of either the American Academy of Orthopaedic Surgeons (AAOS) or the American College of Chest Physicians (ACCP). More respondents reported a preference for the AAOS guidelines than the ACCP guidelines (68% compared with 26%). More than 70% reported that their principal hospital had mandated thromboembolic prophylaxis, and 16.8% of the surgeons made changes in their clinical practices because of the hospital mandates. Respondents ranked aspirin as being associated with the lowest bleeding and wound-drainage complications, whereas low-molecular-weight heparin was ranked as being associated with the highest risks for such complications. Numerous studies are under way to further refine prophylaxis against thromboembolic disease following total hip arthroplasty.
Infection
Infection remains one of the most common reasons leading to reoperation. Kurtz et al. analyzed the Medicare 5% national sample database from 1997 to 2006. They specifically reviewed the data from all patients over the age of sixty-five years and identified 39,929 total hip and 82,362 total knee arthroplasties. The prevalence of infection within two years after surgery was 1.63% for hips and 1.86% for knees. The prevalence of infection between two and ten years was 0.59% for hips and 0.65% for knees. A higher preoperative Charlson index (>5) was identified as a risk factor for a higher infection rate for both total hip arthroplasties (odds ratio = 2.20) and total knee arthroplasties (odds ratio = 2.27). There was no difference with regard to the type of hospital where the index arthroplasty was performed (urban compared with rural or teaching compared with nonteaching). Women had lower infection rates for both total hip arthroplasty (odds ratio = 0.84) and total knee arthroplasty (odds ratio = 0.82). Malinzak et al. conducted a retrospective review of 6108 patients who were managed with 8494 total joint arthroplasties from 1991 to 2004 at a single center. The rate of deep infection was 0.51%, with infection being noted after thirty total knee and thirteen total hip arthroplasties. The risk factors included a body mass index of >30 kg/m2 (p = 0.0025) and diabetes (p = 0.0027). Morbidly obese patients with a body mass index of >50 kg/m2 had an odds ratio of 21.3 (p < 0.0001) when compared with non-obese patients. There was no increased risk as a function of age, inflammatory arthritis, or osteonecrosis.
Resistant strains of bacteria have become more prevalent. Bradbury et al. collected data from four arthroplasty centers. Twenty-two patients with methicillin-resistant Staphylococcus aureus infection around the total joint replacement were managed with débridement and retention of the implant. Nineteen of the twenty-two patients had a failure, and sixteen eventually required removal of the implant. The authors recommended using a two-stage surgical protocol to treat methicillin-resistant Staphylococcus aureus infections. Toulson et al. reported the clinical outcomes for eighty-four hips that were treated with a two-stage protocol at a tertiary joint arthroplasty center. The original infection was eradicated in eighty of the eighty-four hips. All four failures involved methicillin-sensitive organisms, either Staphylococcus aureus (three) or Staphylococcus epidermidis (one). Six hips initially had a successful result but later had development of an infection caused by a different organism. No correlation with clinical success or failure was found with regard to organism, demographic characteristics, surgical techniques, or medical comorbidities. It is important to note that all twenty-one infections with multiple-drug-resistant organisms were successfully treated with this protocol. Duncan et al. have perhaps the most extensive clinical experience with the two-stage protocol involving the use of a spacer during the intervening period. In thirty-nine patients with methicillin-resistant organisms, the infection recurrence rate was 18%. This rate was in distinct contrast to a 4% recurrence rate in another patient cohort with methicillin-sensitive organisms. Moreover, there were worse clinical outcomes in the patients with methicillin-resistant organisms, even with successful treatment of the infection.
Dislocation
Multiple factors are involved in hip instability. Some are related to the surgical technique, and others are related to implant design. Holubowycz et al. conducted a prospective, randomized trial evaluating the efficacy of using a larger-diameter femoral head to reduce the rate of dislocation; 643 patients were randomized intraoperatively to receive either a 28 or 36-mm femoral head. There were no differences between the groups in terms of demographic characteristics. The dislocation rate following primary arthroplasty was 0.8% for 36-mm heads and 4.3% for 28-mm heads. The dislocation rate following revision hip arthroplasty was more than twofold greater for 28-mm heads than for 36-mm heads (11.1% compared with 4.9%). Malkani et al. reported a significant reduction in the dislocation rate following revision total hip arthroplasty performed through the posterior approach when a posterior capsular repair was combined with a larger-diameter femoral head.
Lubbeke-Wolff et al. reported the efficacy of a preoperative patient-education program to reduce the risk of dislocation. Between 2002 and 2007, 656 total hip arthroplasty patients were enrolled in the program before surgery and 1641 patients were not. The overall dislocation rate was 0.8% among those who were enrolled in the preoperative education program, compared with 2.1% among those who were not enrolled in the program. This significant difference remained even after adjusting for demographic characteristics and risk factors for dislocation. These data collectively underscore the importance of a comprehensive approach to reducing dislocation, involving patient education, implant design, and surgical techniques.
Stem Fracture
Fracture of the femoral stem is rare. Williams et al. reviewed the United States Food and Drug Administration "Manufacturer and User Facility Device Experience" (MAUDE) database to identify reports on stem fractures in total hip arthroplasties performed from 1996 to 2007 and identified 167 such fractures. Seventy-four percent of the fractures involved stems made of Ti-6Al-4V alloy. Of these, 98% came from three orthopaedic device manufacturers. The number of reported stem fractures averaged six or fewer per year in the first six years of data collection, and in 2002 there was an increase in the fracture rate. The increase was linear. From the database, the authors estimated a fracture incidence of 8.3 per 100,000 cases; however, stem fracture appears to be grossly underreported by clinicians.
Obesity
Lewallen et al. reported high complication rates in a group of forty-one "super obese" patients (body mass index, >50 kg/m2). After a mean duration of follow-up of three years, the rates of surgical and medical complications were 39.5% and 17%, respectively. Intraoperative technical complications occurred in two patients: one patient had an acetabular fracture, and one had a femoral fracture. Five patients died within two years after surgery. While technically feasible, total hip arthroplasty in extremely obese patients appears to be associated with high morbidity.
Patient Comorbidity and Clinical Outcome
Wang et al. demonstrated that the early outcome following total hip arthroplasty was poorer in women than in men. Patients with higher preoperative WOMAC scores had better outcomes, and those with preexisting comorbidities had worse outcomes than the healthier patients did. The investigators concluded that hip arthroplasty should be performed earlier in the disease course when the patient still has adequate levels of physical function. The difference between the sexes was thought to be related in part to the fact that many women would seek surgery at a later stage than men.
Pay-for-performance protocols require that outcomes be adjusted for the severity of illness. All-Patient Refined Diagnosis-Related Groups (APR-DRG) are utilized to pay and evaluate hospitals and eventually will be utilized to pay and evaluate surgeons. Lavernia et al. evaluated 274 patients undergoing a primary total hip or knee arthroplasty. Outcome instruments were administered before surgery and for twenty-four months after surgery. The length of hospital stay increased with the severity of the illness, and the severity of illness was correlated with poorer preoperative quality of well-being and poorer WOMAC scores. The authors concluded that the APR-DRG system did not have a strong correlation with patient-oriented outcomes but was strongly correlated with hospital finances. Jibodh et al. prospectively evaluated seventy-eight patients who underwent eighty revision total hip arthroplasties. The authors collected patient-based outcome measures before and after surgery. There was no relationship between patient satisfaction and demographic characteristics, Charnley class, or history of previous revisions. Patients were less satisfied with the outcome if they had more pain, were dependent on assistive devices for walking, and had limited walking ability (less than thirty minutes) before surgery. The Harris hip score and general health status were independent predictors of patient satisfaction. These data may have implications for patient counseling and pay-for-performance and other outcome-based payment models.
Many arthroplasty surgeons have observed greater patient satisfaction following total hip arthroplasty than following total knee arthroplasty. Bourne, Chesworth, and Davis reviewed a large outcome dataset that was collected prospectively from 1134 patients managed with total hip arthroplasty and 1578 patients managed with total knee arthroplasty. There was greater improvement in WOMAC scores in the total hip arthroplasty group. Overall, 88% of the patients in the hip arthroplasty group and 78% of those in the knee arthroplasty group were satisfied. Differences in patient satisfaction and clinical outcome also have been found between revision total hip arthroplasty and revision total knee arthroplasty. Ghanem et al. administered patient-based outcome questionnaires before and after revision hip arthroplasty (ninety-three patients) and revision knee arthroplasty (110 patients). Patients with failed total knee arthroplasties had worse preoperative SF-36 and WOMAC scores. Revision total hip arthroplasty resulted in higher scores and greater improvement in the physical domain of the SF-36 and in the functional and pain subscales of the WOMAC than did revision total knee arthroplasty. These data underscore the need for further refinement of both revision procedures to optimize their effectiveness in restoring function.
Activity Measurement
The Harris hip score has been in use for four decades for the clinical assessment of patients who have hip disease and those who have had hip surgery. It has been validated against many different outcome measurement instruments and is a physician-administered instrument. Shervin et al. performed a prospective study evaluating the efficacy of a patient-administered Harris hip score and involving three different data-collection methods: paper, touch-screen computer, and a web-based format. The study group included sixty-one patients (thirty-seven men and twenty-four women) with a mean age of sixty-three years. No difference in effectiveness was found among the three different data-collection methods. There was also a high correlation between physician administration and patient administration. These data provide a basis for patients to use this disease-specific instrument to improve data retrieval and utilization of health-care-provider resources in the evaluation of the clinical outcome of total hip arthroplasty.
Some investigators have brought into question the utility and accuracy of current outcome-measurement instruments for the assessment of patients engaged in high-level activities before and after total hip arthroplasty. There may be ceiling effects in association with the current instruments. Vail et al. evaluated the accuracy of a new questionnaire, the Lower Extremity Functional Scale, in a study of 125 patients who were managed with total hip arthroplasty. This scale involves twenty-five questions. Ten of the twenty-five items explained 82% of the variance. These ten items were associated with two distinct factors: seven items were related to activities, and three items were related to running and the running-related environment. Validation of this simple ten-item activity score suggested a discriminative and internally reliable scale that could effectively measure activities and running in different environments. This type of research is especially important for differentiating variations in clinical outcome in different patient populations.
Pain Management
Pain management is an integral part of the overall perioperative patient experience. Many innovative methodologies have been utilized, especially with the evolution of minimal-incision surgery. Hozack et al. conducted a prospective, randomized trial evaluating two different protocols: (1) traditional patient-controlled analgesia with narcotics and (2) a combination of Tylenol, Lyrica, and Celebrex with rescue oral narcotics. All 100 operations were performed with use of a similar surgical technique, anesthesia, and postoperative rehabilitation protocol. The Tylenol-Lyrica-Celebrex group demonstrated lower pain scores during the first twenty-four hours following surgery. There was no difference in patient satisfaction with either pain management protocol. The mean total amount of narcotics used was lower in the Tylenol-Lyrica-Celebrex group (10.6 compared with 17.1 mg), and the patient-controlled analgesia group experienced significantly more itching and nausea.
DepoDur is a newer epidural morphine agent. Rothman et al. reported a high rate of complications in a group of 201 patients who received DepoDur following total hip arthroplasty. These patients were matched with a group of patients who did not receive DepoDur. The control group required significantly more narcotics and reported higher pain scores. However, the DepoDur group had more episodes of pulmonary embolism and supraventricular tachycardia than the control group did. Thus, the efficacy of DepoDur may be outweighed by more frequent medical complications, and its use probably should be limited to selected patients. Another analgesia option is regional blocks. Marino et al.30 conducted a prospective, randomized trial involving 225 patients who underwent unilateral total hip arthroplasty. The patients were randomized to one of three analgesia protocols: (1) continuous lumbar plexus block plus patient-controlled analgesia (Group 1), (2) continuous femoral nerve block plus patient-controlled analgesia (Group 2), and (3) patient-controlled analgesia alone (Group 3). Significantly lower pain scores on the first and second postoperative days were recorded in Group 1. Both regional-analgesia groups had significantly less total narcotic consumption and a lower rate of delirium. In addition, patients in Group 1 achieved a greater walking distance in physiotherapy sessions than did patients in the other two groups. Most importantly, patients in Group 1 reported better satisfaction.
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 articles cited already in this Update, five 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 articles to help guide your further reading, in an evidence-based fashion, in this subspecialty area.
Galea MP, Levinger P, Lythgo N, Cimoli C, Weller R, Tully E, McMeeken J, Westh R. A targeted home- and center-based exercise program for people after total hip replacement: a randomized clinical trial. Arch Phys Med Rehabil. 2008;89:1442-7.
Twenty-three patients were randomized to a supervised center-based physiotherapy program (eleven patients) or an unsupervised home-based program (twelve patients) following primary total hip arthroplasty. The study duration was eight weeks. There was no difference between the groups at the time of the preoperative functional assessment. All patients in both groups demonstrated significant gains in terms of stair-climbing, a six-minute walk, cadence, step length, and reduction of double-support time between the preoperative and postoperative assessments (p < 0.05 for all parameters). However, there was no difference between the groups in terms of any of these functional outcome measures. The authors concluded that most patients can achieve rehabilitation goals through a targeted physiotherapy program at home just as well as at a rehabilitation center. This is important as access and resource utilization become more limited with the anticipated increase in the volume of total hip arthroplasty.
Rozendaal RM, Koes BW, van Osch GJ, Uitterlinden EJ, Garling EH, Willemsen SP, Ginai AZ, Verhaar JA, Weinans H, Bierma-Zeinstra SM. Effect of glucosamine sulfate on hip osteoarthritis: a randomized trial. Ann Intern Med. 2008;148:268-77.
Two hundred and twenty-two patients with hip osteoarthritis were recruited and randomized to a two-year treatment protocol involving either 1500 mg of glucosamine sulfate or placebo. There was no difference between the groups in terms of demographic or clinical variables. Ninety-three percent of the patients completed the treatment. Overall, there was no difference between the groups in terms of the WOMAC pain and functional scores after the treatment period. Moreover, there was no difference in terms of joint-space narrowing. Twelve patients in the glucosamine sulfate group and six patients in the placebo group went on to total hip arthroplasty during the study period. The clinical efficacy of glucosamine sulfate remains to be substantiated with additional clinical trials.
Ilfeld BM, Ball ST, Gearen PF, Le LT, Mariano ER, Vandenborne K, Duncan PW, Sessler DI, Enneking FK, Shuster JJ, Theriaque DW, Meyer RS. Ambulatory continuous posterior lumbar plexus nerve blocks after hip arthroplasty: a dual-center, randomized, triple-masked, placebo-controlled trial. Anesthesiology. 2008;109:491-501.
Twenty-four patients received a four-day lumbar plexus block with use of an indwelling catheter and ropivacaine following total hip arthroplasty, and twenty-three patients received saline solution through the catheter and served as controls. The ropivacaine group achieved required hospital discharge criteria in an average of twenty-nine hours, compared with fifty-one hours for the control patients (p = 0.01). However, three patients in the ropivacaine group experienced falls. Perioperative analgesia is of critical importance for patient satisfaction and accelerated rehabilitation following surgery. While regional blocks have become the standard of care in many communities, the safety of these techniques requires further study.
Coyle D, Coyle K, Vale L, de Verteuil R, Imamura M, Glazener C, Zhu S. Systematic review and economic evaluation of minimally invasive techniques for total hip replacement [technology overview number 39]. Ottawa: Canadian Agency for Drugs and Technologies in Health; 2008.
The authors identified fifty-two articles describing forty-two studies (twelve randomized controlled trials, twenty-two nonrandomized studies, and eight case series) evaluating minimally invasive total hip arthroplasty. An economic evaluation demonstrated that minimally invasive total hip arthroplasty was associated with a higher cost than standard total hip arthroplasty was ($20,400 compared with $19,100). The number of quality-adjusted life-years gained was also greater in association with minimally invasive total hip arthroplasty (7.48 compared with 7.47). The incremental cost per quality-adjusted life-year gained was $148,300. On the basis of this analysis, the authors concluded that it would be more cost-effective to spend resources evaluating any potential differences in the long-term revision rates rather than focusing on the development of minimally invasive techniques. The major limitations were the lack of long-term clinical data for minimally invasive total hip arthroplasty and the relatively small number of patients in these studies. Another limitation was the heterogeneity in economic data from different countries and health-care-delivery systems.
Glyn-Jones S, Isaac S, Hauptfleisch J, McLardy-Smith P, Murray DW, Gill HS. Does highly cross-linked polyethylene wear less than conventional polyethylene in total hip arthroplasty? A double-blind, randomized, and controlled trial using roentgen stereophotogrammetric analysis. J Arthroplasty. 2008;23:337-343.
Fifty-four patients were randomized to either highly cross-linked polyethylene or conventional polyethylene during primary total hip arthroplasty with use of an identical implant system and surgical techniques. Three-dimensional head penetration was determined over two years. Both groups demonstrated substantial penetration in the first three months (0.22 mm for the highly cross-linked polyethylene group and 0.21 mm for the conventional polyethylene group). Head penetration was significantly less after three months in the highly cross-linked polyethylene group (0.06 compared with 0.10 mm; p = 0.04). Longer-term data are necessary to determine if the wear rate will remain different and if there is an increased risk of fracture in association with the highly cross-linked material. Moreover, reduction of osteolysis has yet to be fully documented.
Della Valle CJ, Mesko NW, Quigley L, Rosenberg AG, Jacobs JJ, Galante JO. Primary total hip arthroplasty with a porous-coated acetabular component. A concise follow-up, at a minimum of twenty years, of previous reports. J Bone Joint Surg Am.2009;91:1130-5.911130
2009
[PubMed][CrossRef]
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;91:773-82.91773
2009
[CrossRef]
Wall SJ, Mears SC. Analysis of published evidence on minimally invasive total hip arthroplasty. J Arthroplasty.2008;23(7 Suppl):55-8.2355
2008
[CrossRef]
Gofton W, Dubrowski A, Tabloie F, Backstein D. The effect of computer navigation on trainee learning of surgical skills. J Bone Joint Surg Am.2007;89:2819-27.892819
2007
[CrossRef]
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;91:128-33.91128
2009
[CrossRef]
Della Valle CJ, Nunley RM, Raterman SJ, Barrack RL. Initial American experience with hip resurfacing following FDA approval. Clin Orthop Relat Res.2009;467:72-8.46772
2009
[CrossRef]
Stulberg BN, Trier KK, Naughton M, Zadzilka JD. Results and lessons learned from a United States hip resurfacing investigational device exemption trial. J Bone Joint Surg Am.2008;90 Suppl 3:21-6.9021
2008
[CrossRef]
Antoniou J, Zukor DJ, Mwale F, Minarik W, Petit A, Huk OL. Metal ion levels in the blood of patients after hip resurfacing: a comparison between twenty-eight and thirty-six-millimeter-head metal-on-metal prostheses. J Bone Joint Surg Am.2008;90 Suppl 3:142-8.90142
2008
[CrossRef]
Daniel J, Ziaee H, Pradhan C, McMinn DJ. Six-year results of a prospective study of metal ion levels in young patients with metal-on-metal hip resurfacings. J Bone Joint Surg Br.2009;91:176-9.91176
2009
[CrossRef]
Pandit H, Glyn-Jones S, McLardy-Smith P, Gundle R, Whitwell D, Gibbons CL, Ostlere S, Athanasou N, Gill HS, Murray DW. Pseudotumours associated with metal-on-metal hip resurfacings. J Bone Joint Surg Br.2008;90:847-51.90847
2008
[CrossRef]
Amstutz HC, Le Duff MJ, Campbell P. Ten years of experience with metal-on-metal hybrid hip resurfacing: a review of 1000 Conserve Plus. J Arthroplasty.2008;23:318.23318
2008
Pattyn C, De Smet KA. Primary ceramic-on-ceramic total hip replacement versus metal-on-metal hip resurfacing in young active patients. Orthopedics.2008;31:1078.311078
2008
[CrossRef]
Akbar M, Mont MA, Heisel C, Marker DR, Ulrich SD, Seyler TM. [Resurfacing for osteonecrosis of the femoral head]. Orthopade.2008;37:672-8. German.37672
2008
[CrossRef]
Li J, Xu W, Xu L, Liang Z. Hip resurfacing for the treatment of developmental dysplasia of the hip. Orthopedics.2008;31:1199.311199
2008
Amstutz HC, Le Duff MJ, Harvey N, Hoberg M. Improved survivorship of hybrid metal-on-metal hip resurfacing with second-generation techniques for Crowe-I and II developmental dysplasia of the hip. J Bone Joint Surg Am.2008;90 Suppl 3:12-20.90
2008
McBryde CW, Shears E, O'Hara JN, Pynsent PB. Metal-on-metal hip resurfacing in developmental dysplasia: a case-control study. J Bone Joint Surg Br.2008;90:708-14.90708
2008
[CrossRef]
Newman MA, Barker KL, Pandit H, Murray DW. Outcomes after metal-on-metal hip resurfacing: could we achieve better function? Arch Phys Med Rehabil.2008;89:660-6.89660
2008
[CrossRef]
Moonot P, Singh PJ, Cronin MD, Kalairajah YE, Kavanagh TG, Field RE. Birmingham hip resurfacing: is acetabular bone conserved? J Bone Joint Surg Br.2008;90:319-23.90319
2008
[CrossRef]
Kluess D, Zietz C, Lindner T, Mittelmeier W, Schmitz KP, Bader R. Limited range of motion of hip resurfacing arthroplasty due to unfavorable ratio of prosthetic head and femoral neck diameter. Acta Orthop.2008;79:748-54.79748
2008
[CrossRef]
Lavigne M, Rama KR, Roy A, Vendittoli PA. Painful impingement of the hip joint after total hip resurfacing: a report of two cases. J Arthroplasty.2008;23:1074-9.231074
2008
[CrossRef]
Olsen M, Davis ET, Waddell JP, Schemitsch EH. Imageless computer navigation for placement of the femoral component in resurfacing arthroplasty of the hip. J Bone Joint Surg Br.2009;91:310-5.91310
2009
[CrossRef]
Ganapathi M, Vendittoli PA, Lavigne M, Günther KP. Femoral component positioning in hip resurfacing with and without navigation. Clin Orthop Relat Res.2009;467:1341-7.4671341
2009
[CrossRef]
Bailey C, Gul R, Falworth M, Zadow S, Oakeshott R. Component alignment in hip resurfacing using computer navigation. Clin Orthop Relat Res.2009;467:917-22.467917
2009
[CrossRef]
Jameson SS, Langton DJ, Natu S, Nargol TV. The influence of age and sex on early clinical results after hip resurfacing: an independent center analysis. J Arthroplasty.2008;23(6 Suppl 1):50-5.2350
2008
[CrossRef]
Morlock MM, Bishop N, Zustin J, Hahn M, Ruther W, Amling M. Modes of implant failure after hip resurfacing: morphological and wear analysis of 267 retrieval specimens. J Bone Joint Surg Am.2008;90 Suppl 3:89-95.9089
2008
[CrossRef]
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;90:1291-7.901291
2008
[CrossRef]
Hart AJ, Buddhdev P, Winship P, Faria N, Powell JJ, Skinner JA. Cup inclination angle of greater than 50 degrees increases whole blood concentrations of cobalt and chromium ions after metal-on-metal hip resurfacing. Hip Int.2008;18:212-9.18212
2008
McGrath MS, Marker DR, Seyler TM, Ulrich SD, Mont MA. Surface replacement is comparable to primary total hip arthroplasty. Clin Orthop Relat Res.2009;467:94-100.46794
2009
[CrossRef]
Spencer S, Carter R, Murray H, Meek RM. Femoral neck narrowing after metal-on-metal hip resurfacing. J Arthroplasty.2008;23:1105-9.231105
2008
[CrossRef]
Marino J, Russo J, Kenny M, Herenstein R, Livote E, Chelly JE. Continuous lumbar plexus block for postoperative pain control after total hip arthroplasty. A randomized controlled trial. J Bone Joint Surg Am.2009;91:29-37.9129
2009