By Peter Brooks, MD, FRCS(C)
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The Case for Hip Resurfacing
Hip resurfacing has several appealing features for the younger patient with hip arthritis. First, considerable bone is preserved in the upper femur compared with traditional hip replacement. Millimeters, rather than inches, are removed. Second, loading of the upper femur is more normal in that the body weight is applied to the top of the femur instead of down the stem to the interior of the upper thigh. As a result, the progressive bone redistribution that takes place for several years after hip replacement does not occur with hip resurfacing.
Together, these two factors result in much less proximal femoral bone loss after resurfacing than after hip replacement. Long stems and bone grafting are therefore not needed for revision of a resurfacing device. Resurfacing can be revised to a standard total hip.
Additionally, the large femoral head of a resurfacing makes dislocation — the principal reason for revision surgery, according to U.S. federal databases ‒ quite rare. Leg length inequality, probably the second most common complaint following total hip replacement, also is rare with resurfacing.1
The stability and normal loading of hip resurfacing allow patients to return to unrestricted activity within a year of the procedure.2,3 This includes running, jumping, impact sports, manual labor and other activities that typically are discouraged following total hip replacement.
Complications of Hip Resurfacing
Concerns have been raised about metal debris from the bearings used in hip resurfacing. High levels of metal debris can result in pain, inflammation, swelling, tissue necrosis and pseudotumors.
Most of the problems with metallosis have occurred using modular metal-on-metal total hip replacement (MOM THR), not resurfacing. Unfortunately, the large heads involved in these procedures exerted excessive torque on trunions designed to accommodate much smaller head diameters.4 Micromotion, fretting and corrosion resulted in high metal ion levels and, in some cases, pseudotumors. MOM THR is no longer performed at most centers, including Cleveland Clinic.
Resurfacing is not the same as MOM THR. There is no modularity and no trunion. The risk of pseudotumor is 0.1 to 0.3 percent.5,6 In resurfacing, only three scenarios can result in excessive metallosis:
- A poorly designed resurfacing device. Several devices are no longer on the market. Today, the Birmingham Hip Resurfacing System (BHR) (Smith & Nephew) is the only FDA-approved resurfacing device available in the U.S. It has had the longest and best track record.
- Component malposition. Malposition of the socket can lead to edge loading and high levels of metal debris.
- Poor patient selection. We have learned that hip resurfacing is most successful in large individuals, usually men, under age 65. It should be avoided in small females and in patients with avascular necrosis or hip dysplasia.
In the absence of one of these three scenarios, metal ion levels remain very low and do not seem to pose a health risk. In fact, after extensive adjustment for confounding factors, mortality rates are lower with resurfacing compared with total hip replacement, and the risk of malignancy appears to decrease following hip resurfacing compared with the risk in an age and sex matched population.7-9 Mechanical complications, such as femoral neck fracture or loosening, are unusual.4
Outcomes Speak for Themselves
In registry data, results with the BHR have surpassed those for all other devices.10
Success rates in young men have been exceptionally good. Aseptic survivorship rates of 99 percent and 100 percent at 10 and 14 years, respectively, have been reported in males under age 50 from two large centers in the UK.11,12 At Cleveland Clinic, our survivorship in this challenging group is 100 percent.
In the series of the designing surgeon (Derek McMinn, MD, FRCS), the success rate at 15 years was 98 percent in males and 92 percent in females, including all ages and diagnoses.13
At Cleveland Clinic, we have performed more than 2,000 BHR procedures (see Figure for an example). The average patient age has been 53 (range, 14 to 84); 73 percent of patients have been male. We have had two femoral neck fractures, two cases of late femoral head collapse and two instances of metallosis (one in a small dysplastic female, one from socket malposition). Neither patient with metallosis developed a destructive pseudotumor. Additional imaging, such as CT scans for femoral anteversion and standing lateral hip X-rays for pelvic tilt, aid in patient selection. Our overall success rate is over 99 percent at up to eight years.
Figure. Right total hip replacement with left BHR. Note the bone loss of the upper femur.
The Bottom Line
Hip resurfacing can provide excellent outcomes in properly selected patients when accurate technique and a well-designed implant are used. In the absence of one or more of these factors, metallosis may occur. Resurfacing allows full activity to be restored for the younger, active patient, and revision options are favorable.
- Herman KA, Highcock AJ, Moorehead JD, et al. A comparison of leg length and femoral offset discrepancies in hip resurfacing, large head metal-on-metal and conventional total hip replacement: a case series. J Orthop Surg Res. 2011;6:65.
- Pollard TCP, Baker RP, Eastaugh-Waring SJ, et al. Treatment of the young active patient with osteoarthritis of the hip. A five- to-seven-year comparison of hybrid total hip arthroplasty and metalon-metal resurfacing. J Bone Joint Surg Br. 2006;88:592-600.
- Zywiel MG, Marker DR, McGrath MS, et al. Resurfacing matched to standard total hip arthroplasty by preoperative activity levels ‒ a comparison of postoperative outcomes. Bull NYU Hosp Jt Dis. 2009;67:116-119.
- Carrothers AD, Gilbert RE, Jaiswal A, et al. Birmingham hip resurfacing: the prevalence of failure. J Bone Joint Surg Br. 2010;92:1344-1350.
- Canadian Hip Resurfacing Study Group. A survey on the prevalence of pseudotumors with metal-on-metal hip resurfacing in Canadian academic centers. J Bone Joint Surg Am. 2011;93(suppl 2):118-121.
- Garbuz DS, Tanzer M, Greidanus NV, et al. Metal-on-metal hip resurfacing versus large-diameter head metal-on-metal total hip arthroplasty. Clin Orthop Relat Res. 2010;468:318-325.
- Kendal AR, Prieto-Alhambra D, Arden NK, et al. Mortality rates at 10 years after metal-on-metal hip resurfacing compared with total hip replacement in England. BMJ. 2013;347:f6549.
- McMinn DJ, Snell KIE, Daniel J, et al. Mortality and implant revision rates of hip arthroplasty in patients with osteoarthritis: registry based cohort study. BMJ. 2012;344:e3319.
- National Joint Registry for England and Wales. 9th Annual Report. www.njrcentre.org.uk. Accessed Oct. 20, 2014.
- Australian Orthopaedic Association. National Joint Replacement Registry Annual Report 2013, p. 104. aoanjrr.dmac.adelaide.edu.au/en/annual-reports-2013. Accessed Oct. 20, 2014.
- Matharu GS, McBryde CW, Pynsent WB, et al. Outcome of the Birmingham Hip Resurfacing in patients aged < 50 years up to 14 years postoperatively. Bone Joint J. 2013;95-B(9):1172-1177.
- Murray DW, Grammatopoulos G, Pandit H, et al. The ten-year survival of the Birmingham hip resurfacing. An independent series. J Bone Joint Surg Br. 2012;94:1180-1186.
- The McMinn Centre. BHR & Other Options: The 15 Year Results. Winter 2013/2014. mcminncentre.co.uk. Accessed Oct. 20, 2014.
About the Author
Dr. Brooks is a staff physician in the Center for Adult Reconstruction in the Department of Orthopaedic Surgery and Chief of Surgery at Cleveland Clinic’s Euclid Hospital.
Disclosure: Dr. Brooks reports that he is a consultant for Stryker and for Smith & Nephew.