Cartilage Degeneration in Relation to Repetitive Pressure Case Study of a Unilateral Hip Hemiarthroplasty Patient

Abstract In vivo acetabular contact pressures were measured over 32 months in an elderly man with a pressure instrumented hemiarthroplasty. After death, left (hemiarthroplasty) and right (control) acetabula were explanted. Cartilage thickness and degeneration were quantified from magnetic resonance imaging and histological analysis. Highest repetitive in vivo contact pressures during gait (4.5 to 6.5 MPa) were measured in the superior dome of the acetabulum and decreased at a rate of approximately 1 MPa per year after implant ( R 2 = 0.48, P R 2 = 0.34, P R 2 = 0.35, P P = .23). We conclude that acetabular cartilage degeneration was explained, in part, by repetitive stress, but the degeneration did not appear to be mediated solely by articulation with the metallic endoprosthesis.