Semiquantitative ultrasonographic grading of femoral cartilage: comparison among three knee groups with different clinical statuses.

INTRODUCTION: Ultrasonography (US) can directly visualize the femoral condylar cartilage, but whether semiquantitative US grade distributions differ among knee groups with different clinical statuses in relation to total knee arthroplasty (TKA) for knee osteoarthritis (OA) remains unclear. We hypothesized that semiquantitative US grading would differ significantly among the three knee groups. METHOD: In this prospective cross-sectional study, 60 patients scheduled for unilateral TKA for OA and 27 healthy young adults were recruited. Group A included knees scheduled for TKA; group B included the contralateral knees of the same patients that were not scheduled for TKA, and group C included bilateral knees of healthy participants. Each knee underwent semiquantitative US grading (0-6) of the whole, medial, and lateral femoral condyles. Differences were analyzed with chi-square trend tests and Wilcoxon signed-rank tests. RESULTS: US grading differed significantly across the three groups at the whole, medial, and lateral femoral condyles (all P < 0.0001). Groups A and B each differed significantly from group C at all three regions (all P < 0.0001). Between groups A and B, grading differed significantly at the whole (P = 0.0222) and medial (P = 0.0017) femoral condyles, but not laterally (P = 0.1792). Medial grading was significantly higher than lateral grading in all groups (all P < 0.0001). CONCLUSIONS: Semiquantitative US grading of femoral condylar cartilage differed among three groups representing different clinical statuses in relation to TKA for knee OA. Grades at the medial femoral condyle were higher than those at the lateral femoral condyle in all three groups. Key Points • Semiquantitative ultrasonographic grading of the femoral condylar cartilage differed at the whole, medial, and lateral femoral condyles among three groups representing different clinical statuses. • The grading differed between knees scheduled for TKA and the contralateral knees of the same patients at the whole and medial femoral condyles, but not at the lateral femoral condyle. • Semiquantitative US grades were higher at the medial than at the lateral femoral condyle in all three groups. • Semiquantitative US grading is a non-invasive method for comparing femoral cartilage morphology among three groups representing different clinical statuses.