Cross-linked polyethylene has much less wear than conventional polyethylene and can used in a more bone conserving thickness of 4 mm. We have used it for hip resurfacing since 2001. This study evaluated the effectiveness of a highly cross-linked polyethylene acetabular component for hip resurfacing in patients under age 50. I posed 5 questions: (1) What are the functional results, (2) What are the complications, (3) What is the 10-year implant survivorship, (4) What is the femoral head penetration into the polyethylene, and (5) What is the bone conservation?Background
Questions/Purposes
We originally performed metal-on-metal hip resurfacing using a Townley designed Vitallium Total Articular Replacement Arthroplasty (TARA) curved stemmed prosthesis. Neither the acetabular or femoral components were cemented or had porous coating. The bearing surfaces were consistently polar bearing. The surgical objectives were to preserve bone stock, maintain normal anatomy and mechanics of the hip joint and to approximate the normal stress transmission to the supporting femoral bone. The functional objectives were better sports participation, less thigh pain and limp, less perception of a leg length difference and a greater perception of a normal hip. Metal-on-metal was selected to conserve acetabular bone and avoid polyethylene associated osteolysis. Relatively few cases were performed until the Conserve Plus and later the Birmingham Hip Resurfacing systems became available. We examined the results of metal-on-metal hip resurfacing in patient with at least 10 years of follow-up and an age less than 50 at the time of surgery. We did not have access to the Birmingham Prosthesis until 2006. We performed 101 TARA procedures and 397 Conserve Plus procedures for 357 patients. For the combined series the mean age was 43 and 62% of patients were male. 34 patients had a conventional total hip replacement on the contralateral side. We used both the anterolateral and posterior approaches. All acetabular components were placed without cement and all the Conserve Plus Femoral Components were cemented.BACKGROUND
METHODS
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. 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.BACKGROUND
METHODS
