Diagnostic accuracy of MRI for meniscal tear patterns in ACL-deficient knees: comparison with arthroscopic findings.

BACKGROUND AND

OBJECTIVES

Anterior cruciate ligament (ACL) injuries are frequently associated with meniscal tears. MRI diagnostic performance varies by tear pattern and location and may be influenced by imaging timing and reader variability. This study evaluated pattern-specific MRI accuracy compared with arthroscopic findings and assessed the impact of timing and inter-reader reliability.

METHODS

This retrospective study included consecutive patients undergoing ACL reconstruction with confirmed complete ACL tears and available preoperative MRI. Meniscal tears were classified as horizontal, vertical, radial, complex, and bucket-handle. Arthroscopy served as the reference standard. Diagnostic metrics, inter-reader agreement (κ), and time intervals between injury, MRI, and surgery were analyzed.

RESULTS

A total of 143 patients were included. Medial meniscal tears were present in 81 patients (56.6%) and lateral tears in 69 (48.3%). MRI accuracy was 71.3% for medial tears (sensitivity 86.4%, specificity 51.6%) and 72.0% for lateral tears (sensitivity 88.4%, specificity 56.8%). Bucket handle tear patterns showed the highest inter-reader reliability (κ = 0.78), while radial tears demonstrated the lowest inter-reader reliability (κ = 0.16). In adjusted analyses, neither meniscal location nor any injury-MRI, MRI-surgery, or injury-surgery interval was significantly associated with diagnostic performance (all p ≥ 0.38).

CONCLUSIONS

MRI shows moderate accuracy and fair-to-substantial reliability for meniscal tears in ACL-deficient knees, with the best performance in bucket-handle tear patterns. The greatest inter-reader variability was observed for radial tears. Although no significant association between timing intervals and diagnostic performance was identified, timing-related findings should be interpreted cautiously because of potential measurement error and the retrospective design.

REGISTRATION: The study registration was not performed due to the retrospective design.