Association between grayscale sonographic and clinical findings in severe knee osteoarthritis

Purpose To assess whether ultrasonographic (US) findings associate with clinical findings in severe knee osteoarthritis (OA). Association of US findings with side-of-knee pain and inter-reader agreement of knee US were also evaluated. Methods One-hundred-two patients (in total 123 knees) with severe knee OA were recruited for this cross-sectional study. US was performed by a single observer, and on 53 knees by two independent observers to assess inter-reader reliability. Preoperative clinical data was available for 69 knees. Cutoff values were applied to dichotomize US and clinical findings. The Chi-square test, Mann-Whitney test, and prevalence- and bias-adjusted kappa (PABAK) were applied for statistical analyses. Results Seven of 99 associations tested were statistically significant. Associations were observed between range of flexion and lateral femoral (P = .009) and tibial (P = .001) osteophytes, mediolateral instability and damage to the lateral femoral cartilage (P = .014) and damage to the lateral meniscus (P = .031), and alignment and damage to the lateral femoral cartilage (P < .001), lateral tibial osteophytes (P = .037), and damage to the lateral meniscus (P < .001). A strong association was observed between medial-sided pain and same-sided cartilage damage and osteophytes (P < .001). That inter-reader agreement was excellent on the medial side of the knee joint (PABAK = 0.811-0.887). Conclusions US findings show a rather poor association with clinical OA findings. Inter-reader agreement of knee US is excellent on the medial side.