The purpose of this study was to evaluate the effectiveness of routine pathological examination of operative specimens obtained during primary total hip arthroplasty (THA) performed for osteoarthritis (OA) and rheumatoid arthritis (RA). 100 consecutive patients (50 OA, 50 RA) were prospectively evaluated. A radiological score (Kellgren-Lawrence/Larsen) and a clinical score (Harris Hip Score) were calculated in each case. Specimens of bone and cartilage from the femoral head as well as capsule were obtained intraoperatively. A histological grading (Mankin score) was obtained, and additional histological findings were also reported. In patients with RA the clinical and pathological diagnoses were concordant in 37 (74%) and discrepant in 13 patients (26%). In patients with OA there was concordance in 30 (60%) and discrepancy in 20 patients (40%). Discrepancies were additional findings such as focal osteonecrosis amyloidosis or crystal deposits. Discordance (management alteration) did not occur in any case. Histological evaluation of the capsule and the synovium was more informative than evaluation of bone. Calcium pyrophosphate (CPPD) and amyloid was frequently found in OA suggesting that these substances may contribute to joint damage, and control of their production by therapeutic means may prevent degeneration.
