Accuracy of knee range of motion assessment after total knee arthroplasty

Measurement of knee joint range of motion (ROM) is important to assess after total knee arthroplasty. Our objective was to determine level of agreement and accuracy between observers with different knowledge on total ROM after total knee arthroplasty. Forty-one patients underwent x-ray of active and passive knee ROM (gold standard). Five different raters evaluated observed and measured ROM: orthopedic surgeon, clinical fellow, physician assistant, research fellow, and a physical therapist. A 1-way analysis of variance was used to determine differences in ROM between raters over both conditions. Limit of agreement for each rater for both active and passive total ROM under both conditions was calculated. Analysis of variance indicated a difference between raters for all conditions (range, P = .004 to P < or =.0001). The trend for all raters was to overestimate ROM at higher ranges. Assessment of ROM through direct observation without a goniometer provides inaccurate findings.