A Multimodal Diagnostic Algorithm for Focal Knee Chondral Defects: Correlating Clinical Tests, Musculoskeletal Ultrasound, and MRI-Based ICRS Grading

Background: Focal chondral lesions of the knee are frequently underdiagnosed, and their clinical presentation does not always correlate with structural severity. This study aimed to evaluate the diagnostic utility of clinical examination tests and musculoskeletal ultrasound (MSK-US) in identifying high-grade chondral defects, using MRI-based ICRS grading as the reference standard. Methods: In this observational cross-sectional study, 57 consecutive patients with mechanical knee pain and MRI-confirmed focal chondral lesions were evaluated through standardized clinical examination, MSK-US, and MRI. Clinical maneuvers—including Wilson’s test, McMurray’s test, and ligamentous stability tests—were analyzed using Chi-square tests, Pearson correlations, and odds ratios (OR). Statistical processing was performed in Python. Results: According to MRI grading, 87.7% of lesions were ICRS 3, and 12.3% were ICRS 4. Pain and functional impairment (as measured by the WOMAC) were moderate and comparable across lesion grades. Wilson’s test showed high sensitivity in both ICRS 3 (66%) and ICRS 4 (100%) lesions, but no statistical association with lesion severity (p = 0.955). McMurray’s test demonstrated strong discriminative value, being positive in 30% of ICRS 3 versus 86% of ICRS 4 lesions, and was the only clinical maneuver significantly associated with lesion grade (χ2 = 4.29, p = 0.038; OR = 0.20, 95% CI: 0.05–0.79). Correlation analysis revealed weak associations between clinical tests and the location of compartment-specific defects. MRI identified meniscal tears in 86% of ICRS 4 lesions compared with 30% of ICRS 3 lesions. Conclusions: Symptom severity alone does not reliably distinguish between ICRS Grade 3 and Grade 4 focal chondral lesions. McMurray’s test, while not cartilage-specific, was associated with lesion complexity due to its reflection of concomitant meniscal pathology rather than cartilage depth itself. Accordingly, McMurray’s test should be interpreted as an indirect clinical indicator of combined osteochondral–meniscal involvement. The integration of targeted clinical tests (Wilson’s and McMurray’s), MSK-US and MRI-based ICRS grading may support clinical orientation and preoperative risk stratification, forming a pragmatic diagnostic framework rather than a definitive staging tool.