Cementless Femoral Fixation in Primary Total Hip Arthroplasty

James P. McAuley, M.D., FRCSC

Staff Orthopaedic Surgeon

Anderson Orthopaedic Clinic &

INOVA Center for Joint Replacement

Associate Professor of Orthopaedic Surgery

University of Maryland

Alexandria, VA

A series of 507 consecutive, unselected cementless hip arthroplasties were reviewed to specifically address 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 those who had expired or were lost to follow-up, there were 426 hips with minimum 5- year follow-up. The overall femoral reoperation rate of 2.6% (13 cases) included 7 due to failure of fixation and 6 due to 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, and 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. Though 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 incidences of reoperation, thigh pain, component instability, or stress shielding are not supported by this study.

Looking at specific “high risk” diagnoses, the femoral component results are encouraging.

In 22 DDH cases , with a mean radiographic and clinical follow-up of 10.1 years, no AML stems has been revised, and all are bone ingrown.

In 55 cases of stage III and IV AVN in young patients (average 31 years with 117-month follow-up), no stem required revision for aseptic loosening, and none was loose radiographically. There was a high (20%) revision rate for wear and lysis (6) , dislocation (3) or infection (1).

In 69 rheumatoid arthritis patients with mean 9 years follow-up, the survival rate for the stems was 0.98 +/- 0.01.

In 212 elderly patients with >5 year follow-up, there was one stem revised for loosening and radiologic loosening in 0.7%.

Our overall experience, and with specific problematic diagnostic groups, has left us with the conclusion that cementless femoral fixation can reproducibly provide long term stability with minimal morbidity.

Previous Lecture Index Next Lecture