Abstract
Purpose
Complete wear-out of Polyethylene (PE) liner results in severe metallosis following articulation of the artificial head with the acetabular metal shell. We postulated that an adverse response can be led to surrounding bone tissue and new implant after revision surgery because the amount of PE wear particle is substantial and the metal particles are infiltrated in this catastrophic condition. We evaluated clinical characteristics and the survival rate of revision total hip arthroplasty (THA) performed in patients with severe metallosis following failure of PE liner.
Materials and Methods
Between January 1996 and August 2004, severe metallosis following complete wear-out of PE liner were identified during revision THA in 28 hips of 28 patients. One patient had died at 7 days after surgery and 3 patients could not be reached at 5 year follow-up. Twenty-four hips of 24 patients (average age, 47.5 years) were followed for at least 6.5 years (average, 11.3 years; range, 6.5–15.9 years) and were evaluated. The mean time interval between prior surgery and the index revision surgery was 9.6 years (range, 4.0–14.3 years). The indications for revision surgery were osteolysis around well-fixed cup and stem in 22 hips and osteolysis with aseptic loosening of the cup in 2 hips. Bubble sign was observed on preoperative radiograph in 10 hips. Total revision, cup revision, and solitary bearing change were performed in 13, 10, and one hip respectively. A cementless implant was used in 23 hips and acetabular reinforcement ring was used in one. Clinical evaluation was performed using Harris hip scores and Kaplan-Meier survival analysis was performed. Multivariate analysis was performed with age, gender, BMI, bone defect type, existence of bubble sign and type of revision surgery as variables to evaluate the association with osteolysis or loosening.
Results
One patient who had died from an unrelated medical condition at 6.5 years had hip that were functioning well at the time of death. Average Harris hip score improved from 64.5 points preoperatively to 81.9 points at the last follow-up. Wear and osteolysis were detected at average 8.9 years (3.1–13.5 years) after revision in 14 hips. Acetabular cup was loosened in 9 hips. Re-revision of cup was performed in 5 hips and re-revision of both cup and stem was done in 2 hips. In another hip, cup removal and artificial neck cutting was performed due to severe bone loss following two times of cup re-revision. With radiographic evidence of osteolysis as the end point, the 15-year survival rate was 35.3% (95% confidence interval [CI], 11.6%–59.0%). With radiographic loosening of any implant as the end point, the 15-year survival rate was 54.0% (95% CI, 27.9%–80.1%). Multivariate analysis revealed no variable that had a significant association with osteolysis or loosening.
Conclusion
The survival rate of revision THA in patients with metallosis following a failure of a PE liner was low. Substantial amount of PE wear debris and the infiltration of metallic wear particles in the periprosthetic tissues might lead to progressive bone loss and implant loosening after revision THA.
