The aim of this study was to analyze subchondral bone scan uptake in osteoarthritic knees with reference to subchondral bone microstructure and articular cartilage histology.
This cross-sectional, laboratory study evaluated 123 human distal femoral condyle specimens of 67 patients after joint replacement surgery. All patients were preoperatively examined with bone scan of the knee joint. Specimens were evaluated for cartilage histology and micro-computed tomography analysis of subchondral bone. Data between bone scan, histology and micro-computed tomography were statistically analyzed using either coefficient of correlation, Student's t-test or one-way analysis of variance with Tukey post hoc test.
Bone scan grading and histological articular cartilage degeneration scores showed significant correlation (r = 0.812, P < 0.001). Both bone scan positive and histologically confirmed osteoarthritis samples showed increase in subchondral trabecular bone volume and thickness, reflected in micro-computed tomography. Overall, positive predictive value (%) of bone scan for osteoarthritic cartilage lesions was 91.9%, and the sensitivity and specificity were 88.3% and 60%, respectively. Histology showed that bone scan has both a high positive predictive and a low negative predictive value for detection of osteoarthritic cartilage lesions.
Bone scan uptake correlated with articular cartilage degeneration in osteoarthritic knees. Bone scan may be a useful diagnostic tool that reflects pathologic changes of cartilage in osteoarthritis.