Abstract
BACKGROUND
The most common salvage of a failed metal-on-metal hip resurfacing is to remove both the femoral and acetabular resurfacing components and perform a total hip replacement. The other choices are to perform an acetabular or femoral only revision. A one or two piece acetabular component or a polyethylene bipolar femoral component that matches the retained metal resurfacing acetabular component is used. The considerations in favor of performing a one component resurfacing revision are maintaining the natural femoral head size, limiting the surgical effort for the patient and surgeon, and bone conservation. There are often favorable cost considerations with single component revision surgery.
The reasons for femoral component revision are femoral neck fracture, femoral component loosening and an adverse reaction to metal wear debris. Performing a femoral component only revision requires a well fixed and well oriented acetabular component. Acetabular revision is most often performed for an adverse reaction to metal wear debris or loosening.
METHODS
81 acetabular revisions and 46 femoral revisions were evaluated 4 to 14 years after surgery. 83% of patients had their initial surgery at outside institutions. The mean age was 46 and 65% of patients were women. A two piece titanium backed polyethylene component was used in 44 patients and a one or two piece metal component was used in 37. A dual mobility femoral prosthesis mated to a retained metal acetabular component was used for the femoral revisions and no conversions to a metal-on-metal total hip replacement were performed. We selected polyethylene acetabular components for patients with adverse reactions to metal wear debris if their femoral component was less than 48 mm or if there was no matching metal acetabular component available for their femoral component. We used dual mobility components for femoral loosening, femoral neck fractures and adverse reactions to metal wear debris in patients with well-fixed and well oriented metal acetabular components. Dual mobility components were also used if there are any concerns about the femoral component or in some older patients. We performed one component revisions rather than conversion to total hip replacement on 88% of patients presenting with failed resurfacing prostheses.
RESULTS
There were no failures with polyethylene acetabular components. There were two failures due to ongoing adverse metal reactions in patients receiving metal revision acetabular components. There was one failure with a dual mobility prosthesis due to accelerated polyethylene wear from undetected edge loading on a retained worn metal acetabular component. There were two infections and one patient with continued pain. There were no dislocations. The average Harris Hip Score was 94. The UCLA activity score was 6 or greater for all but 4 patients. There were 6 revisions to total hip replacement. The Kaplan-Meier survivorship was 94%. 95% of patients rated their outcome as excellent or good.
CONCLUSIONS
Failed metal-on-metal hip resurfacing prostheses can be successfully revised without conversion to total hip replacement in most instances. A detailed knowledge of matching prostheses is necessary. Polyethylene prostheses for the acetabular or femoral reconstruction are often needed.
