Total hip arthroplasty - Concerns with extensively porous coated femoral components

A series of 507 consecutive, unselected cementless hip arthroplasties performed by one surgeon was reviewed to address specifically potential concerns with the use of extensively coated femoral components, including the frequency and nature of reoperation, thigh pain, component stability, osteolysis, and stress shielding. Excluding hips in patients who had died or were lost to followup, there were 426 hips with minimum 5-year followup. The overall femoral reoperation rate of 2.6% (13 cases) included seven for failure of fixation and six for osteolysis. Of the unrevised cases, 96% of the femoral components showed radiographic bone ingrowth, and 3.7% showed a stable fibrous pattern. Fixation did not deteriorate with time. A 2.9 % incidence of activity limiting thigh pain did affect clinical outcome (limp, ambulation tolerance, support), but there were no clinical or radiographic predisposing variables. There was no detectable femoral osteolysis in 88.3% of cases. The remainder had lesions confined to Gruen Zones 1 and 7, suggesting that circumferential extensive coating was protective against distal osteolysis. Although osteolysis did not affect component stability, in six cases it did result in pathologic trochanteric fracture, contributing to the frequency of reoperation. Stress shielding was common (25%) and was related to older patients and the use of larger diameter stems (> 15 mm), but did not predispose to thigh pain, loosening, osteolysis, or an inferior clinical result. These results documented the clinical and radiographic success in the use of extensively coated cementless femoral components. Debris generation from wear and resulting osteolysis remain significant concerns in a hip arthroplasty with this design as with many others. However, concerns about the high incidence of reoperation, thigh pain, component instability, or stress shielding are not supported by this study.