Long-Term Results of Hip Arthroplasty Using Extensive Porous-Coated Stem-A Minimum Follow-Up of 15 Years

Introduction: We report the clinical and radiographic results of hip arthroplasty using extensive porous-coated stems over 15 years in Korea. Methods: This retrospective study included 210 patients (268 hips) who underwent total hip arthroplasties (232 hips) and bipolar hemiarthroplasties (36 hips) between June 1996 and December 2002 for avascular necrosis of the femoral head, hip fracture, or osteoarthritis, after excluding those who died or were lost to follow-up. One senior author (K.H.M.) evaluated Harris Hip Score (HHS); limping gait; and leg length discrepancy, and 3 independent reviewers assessed the radiographic findings, including the level of stress shielding, Dorr classification, subsidence and loosening of femoral stem, heterotopic ossification (Brooker classification), osteolysis of acetabulum, wear rate of the polyethylene liner, component loosening, and revision rate. Results: The mean follow-up duration was 16.9 years and average age at operation was 50.9 years. The HHS improved at the last follow-up. Stress shielding was grade 1 in 185 hips, grade 2 in 35 hips, grade 3 in 37 hips, and grade 4 in 11 hips. Femoral stem subsidence was 3 mm in 6 hips. Femoral stems with stable bony ingrowth were observed in 258 hips, fibrous stable femoral stems in 4 hips, and unstable femoral stems in 6 hips. Heterotopic ossification was class 1 in12 and class 2 in 4 hips. Revision surgery was performed for periprosthetic osteolysis of cup (45 hips), recurrent dislocation (1), unstable femoral stem (1), and infection (1). The Kaplan-Meier survivorship at the 15-year follow-up was 86.2%. The survivorship of femoral stem at 15 years was 99.3%, and if including impending revision due to unstable femoral stem was 97.1%. Disscussion: This study has all the limitations inherent with a retrospective design. However, a large number of patients in this cohort operated on by a single surgeon and a long-term follow-up are some of the potential advantages of the current study. Conclusions: At the 15-year follow-up, extensive porous-coated stem showed relatively good survivorship even in geriatric patients (Dorr type C).