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Unformatted text preview: JBJA Journal of Bone and Joint Surgery - American 1996 - 1998 May 1996, Volume 78-A, Number 5 755 The Porous-Coated Anatomic Total Hip Prosthesis: Failure of the Metal-Backed Acetabular Component* Article AUTHOR(S): ASTION, DONNA J., M.D., NEW YORK; SALUAN, PAUL, M.D.; STULBERG, BERNARD N., M.D., CLEVELAND, OHIO; RIMNAC, CLARE M., PHD; LI, STEPHEN, PHD, NEW YORK, N.Y. Investigation performed at The Hospital for Special Surgery, New York City; University Hospitals of Cleveland, Case Western Reserve University, The Cleveland Clinic Foundation, and the Cleveland Center for Joint Reconstruction, Cleveland; and Northwestern University Medical School, Chicago J Bone Joint Surg [Am] 1996; 78-A; 755-66 ABSTRACT: One hundred and ninety-nine total hip arthroplasties were performed, between 1983 and 1987, in 173 patients by three surgeons using the initial design of the porous-coated anatomic prosthesis. The acetabular component was a preassembled, metal-backed polyethylene device, with beads sintered to the metal backing to allow bone ingrowth and two pegs for initial fixation. Twenty-three acetabular components (12 per cent) failed because of either migration or severe osteolysis. The radiographic appearance of osteolysis was positively associated with the duration that the implant had been in situ (p < 0.001). The prevalence of osteolysis was also significantly greater in acetabular components with an outer diameter of fifty-five millimeters or less (a polyethylene thickness of 8.5 millimeters or less) (p = 0.03). Thirteen hips were revised at a mean of 69.5 months (range, thirty-three to ninety- one months) after the index operation. Examination of the retrieved acetabular components revealed extensive polyethylene damage on the articular and back surfaces of the liners. Cracks in the polyethylene rim of the liner and deformation of the anti-rotation notch in the polyethylene rim were common findings. The density of the polyethylene was greater than expected, and more particles than anticipated had not fused with the surrounding polyethylene. The results of this study suggest that factors related to both the design and the material contributed to the failure of these porous-coated anatomic acetabular components. CLINICAL RELEVANCE: Patients who have had a total hip arthroplasty with the initial design of the porous-coated anatomic acetabular component should be closely monitored clinically for the onset of pain and radiographically for the development of osteolytic lesions or migration of the component. These findings are associated with impending failure of the component and may warrant revision of this portion of the hip replacement. The use of metal-backed acetabular components for total hip arthroplasty was first recommended by Harris and Penenberg as a means of more uniformly distributing load to the cement mantle of the acetabulum (15) . It was hypothesized that this would increase the long-term fixation of acetabular components inserted with cement. The advent of components inserted with cement....
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This note was uploaded on 07/25/2011 for the course EMA 6580 taught by Professor Staff during the Spring '08 term at University of Florida.
- Spring '08