Intraobserver and interobserver reliability of the assessment of the patellar articular cartilage in osteoarthritic patients undergoing total knee arthroplasty.

This study was performed to investigate intraobserver and interobserver reliability of the intraoperative assessment of patellar cartilage status and the decision on patellar resurfacing based on the cartilage assessment in osteoarthritic patients undergoing total knee arthroplasty. Photographs of patellar cartilage were taken in 80 knees of 53 patients undergoing total knee arthroplasty. Three investigators assessed the depth and size of the cartilage lesion and made a decision on patellar resurfacing, using the photographs twice. Intraobserver and interobserver reliabilities were calculated with the kappa coefficient. Cartilage assessment had substantial intraobserver (kappa = 0.77 for depth and 0.71 for size) and moderate interobserver (kappa = 0.54 for depth and 0.45 for size) reliabilities. Decision on patellar resurfacing had almost perfect intraobserver and substantial interobserver reliabilities (kappa = 0.88 and 0.68, respectively). We found that intraoperative assessment of the patellar articular cartilage and the decision for patellar resurfacing are reliable.