By Michael A. Mont, MD, Mike S. McGrath, MD, and Michael G. Zywiel, MD
Metal-on-metal total hip resurfacing arthroplasty has become an increasingly popular option over the past ten years. Multiple purported benefits of this procedure have been described1-15. In addition, several reports have suggested that the outcomes of this procedure are improved with proper patient selection16-19. The purpose of this presentation was to describe the reported benefits of this procedure as well as the patient-selection process.
Compared with conventional total hip arthroplasty, hip resurfacing may be associated with several advantages and unique risks. One advantage is increased femoral bone stock because the neck and most of the head are retained1,2. Also, compared with stemmed prostheses, resurfacing prostheses may be simpler to place in patients who have extra-articular deformities of or hardware attached to the proximal aspect of the femur14. In addition, resurfacing may be associated with a greater hip range of motion, improved gait parameters15, lower dislocation rates, and increased activity levels7. Finally, in the case of failure, revision to a conventional prosthesis is straightforward, with results that are comparable with those obtained with a primary stemmed total hip arthroplasty12,13. Risks include femoral neck fracture, loosening of the implant, and exposure to metal ions16-20.
Proper patient selection is important in hip resurfacing16-19. Patients who have osteoarthritis and who have not responded to nonoperative treatment are indicated for this procedure1-3. Resurfacing has also been performed on patients who have osteonecrosis, rheumatoid arthritis, and Legg-Calvé-Perthes disease, and these patients have had good-to-excellent short-term results9-11. Contraindications include insufficient bone stock in the femoral head, severe osteopenia, large cysts at the femoral head or neck, a narrow femoral neck, notching of the femoral neck, and severe obesity (body mass index >35 kg/m2), all of which are associated with an increased risk of femoral neck fracture16-19. Another contraindication is metal hypersensitivity, which may be associated with pseudotumors in some patients20. Age does not appear to be a contraindication on the basis of the results in the literature21.
The results associated with hip resurfacing arthroplasty are promising, and the procedures may have multiple benefits for patients who meet the selection criteria. Longer-term follow-up will be necessary to confirm these results.
Early Outcome Results of Metal-on-Metal Hip Resurfacing
By Paul E. Beaulé, MD, FRCSC
Background
Renewed interest in the clinically proven low wear of the metal-on-metal bearing combined with the capacity of inserting a thin-walled cementless acetabular component1 has fostered the reintroduction of hip resurfacing. Although improved materials will certainly benefit implant survivorship, the difficult technical aspects of performing hip resurfacing will certainly also impact implant survivorship. In their recent report on the results of hip resurfacing after United States Food and Drug Administration approval of the procedure, Della Valle et al. noted a 7.4% failure rate at the time of short-term follow-up1. The purpose of this presentation is to review the current results of a multicenter prospective study on hip resurfacing2 and to compare these results with those obtained with the first fifty hip resurfacing procedures performed by high-volume arthroplasty surgeons3.
Methods
Part 1.
Two hundred patients were prospectively enrolled in a multicenter study and followed for an average of 31.2 months (range, twelve to fifty-four months). Of 200 patients, fourteen (7.0%) required revision surgery at a mean time of 19.5 months (range, three to forty-seven months)2.
Part 2.
We surveyed all fourteen Canadian academic centers with regard to the implantation of hip resurfacing components, and we assessed the first fifty hip resurfacing procedures done by each of five surgeons who perform a high volume of adult reconstructive surgery and who had no prior training in hip resurfacing. Seventy-seven percent of the patients were male, 80% of the patients had a diagnosis of osteoarthritis, and the mean age of the patients was 49.3 years.
Results
Part 1.
Patients who had failure of resurfacing were younger and heavier than those who did not have failure, and all were men. Although the radiographic outcome of the initial procedure of patients who underwent revision did not differ from that of patients who did not undergo revision, the patients who underwent revision had lower functional outcome scores at all preoperative and postoperative testing intervals. Most of the failures (ten of fourteen) were related to early acetabular loosening.
Part 2.
Eleven (79%) of fourteen Canadian academic centers were performing hip resurfacing, and the posterior approach was the most commonly used surgical approach at these centers. One center has stopped performing hip resurfacing arthroplasty after initially performing the procedure in fewer than thirty hips.
The overall revision rate was 3.3% at a mean time of two years, with femoral neck fracture (1.6%) being the most common cause of failure3.
Conclusions
This report highlights the importance of patient selection and surgical technique in hip resurfacing arthroplasty. For the most part, high-volume arthroplasty surgeons can expect a low failure rate during the initial learning curve of performing this operation, with femoral neck fracture remaining the leading cause of early failure.
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. Erratum in: Clin Orthop Relat Res. 2009;467:587.46772
2009
[PubMed][CrossRef]
Kim PR, Beaulé PE, Laflamme GY, Dunbar M. Causes of early failure in a multicenter clinical trial of hip resurfacing. J Arthroplasty.2008;23(6 Suppl 1):44-9.2344
2008
O'Neill ME, Beaulé PE, Bin Nasser AB, Garbuz D, Lavigne M, Duncan C, Kim PR, Schemitsch EH. Canadian academic experience with hip resurfacing arthroplasty. Bulletin of the NYU Hospital for Joint Diseases.2009;67:128-31.67128
2009
Unique Complications of Resurfacing
By William N. Capello, MD
The unique complications of surface replacement arthroplasty must be weighed against the potential benefits to determine whether its use is justified in patients who present with severe hip disease.
Femoral neck fracture is a unique complication associated with hip resurfacing, occurring with a prevalence of 1% to 2% in almost all reported series. According to the Australian National Registry, 47% of surface replacement revisions are for fracture1. Femoral fractures can be related to bone density, notching of the femoral neck, and positioning of the femoral component2. Pseudotumors, which differ from aseptic lymphocyte-dominated vasculitis-associated lesions, have only been described in female patients who have undergone surface replacement. Murray et al. reported on twenty hips with pseudotumors, all of which occurred in female patients who had undergone hip resurfacing arthroplasty3. Twelve of those hips required a revision to a conventional hip replacement. It is estimated that a pseudotumor will develop in approximately 1% of patients in the first five years after surgery3. Age and sex are also uniquely associated with the complications of resurfacing. The Australian National Registry reported that, for patients in the age range of sixty-five to seventy-four years, the percentage of patients needing revision was 3.8% for patients who had surface replacement and 1.8% for patients who had conventional total hip replacement1. In patients who were seventy-five years or older, the percentage increased to 9.6% for patients who had surface replacement and 1.9% for patients who had conventional total hip arthroplasty. Older women were noted to have higher complication rates. Although stress-shielding occurs routinely and without consequence after conventional total hip arthroplasty, it may lead to femoral failure due to loss of bone after surface replacement.
Australian Orthopaedic Association National Joint Replacement Registry. Annual report. Adelaide, Australia: Australian Orthopaedic Association; 2006.
2006
Vail TP, Glisson RR, Dominguez DE, Kitaoka K, Ottaviano D. Position of hip resurfacing component affects strain and resistance to fracture in the femoral neck. J Bone Joint Surg Am.2008;90:1951-60.901951
2008
[PubMed][CrossRef]
Murray D, Pandit H, Gill R, Whitwell D, Taylor A, McLardy-Smith P, Gibbons M, Gundle R. Pseudotumours following hip resurfacing. Read at the International Hip Society Closed Meeting; 2008 Aug 24-28; Hong Kong, China.
2008