Abstract
Introduction:
The earliest evidence of particle-induced response is found in the synovium, leading to osteolytic defect. The degree of synovitis can be quantified by magnetic resonance imaging (MRI). This is the first long-term, prospective, matched-pair study using MRI to analyze wear-induced synovitis and osteolysis between rotating-platform posterior-stabilized (RP-PS), fixed-bearing metal-back (FB-MB), and all-polyethylene tibial (APT) designs in active patients with identical femoral components and polyethylene.
Methods:
From September 1999 to October 2001, a matched-pair analysis of 24 TKAs (18 patients, 3 groups: 8 RP-PS, 8 FB-MB, and 8 APT) was performed. TKAs were matched for age, sex, body mass index (BMI), and University of California Los Angeles (UCLA) activity scores. All patients underwent MRI using MAVRIC (multi-acquisition variable-resonance image combination) knee protocol designed to reduce metal susceptibility artifact. Images were evaluated for volumetric measure of synovitis and/or osteolysis and presence of fibrous membrane formation at the cement-bone interface.
Results:
The mean age was 64 ± 5 years (59–72). The mean follow-up was 11.6 ± 0.7 years (10–13). The mean UCLA score at the time of surgery was 8.5 ± 2.6 (5–10). Reactive synovitis was observed in 6 RP-PS (75%), all 8 FB-MB (100%), and 6 APT (75%) knees. There was a significant difference between the volumetric synovitis in RP-PS (4046 mm3 ± 4502 mm3), and FB-MB knees (24498 mm3 ± 22248 mm3), p < 0.001. Osteolysis with bone loss more than 4 mm was seen in 3 FB-MB, 2 APT, but in none of the RP-PS knees. There was no statistical difference for osteolysis between the three designs.
Conclusion:
Based of this study, it appears that particle induced synovitis is evident in all 3 types of bearing surfaces, however, it is significantly less in the RP-PS group. This is in contradiction to the report of retrieval studies.
