Abnormal lateral meniscal signal in MRI after patellar dislocation does not indicate a meniscal tear: MR findings with surgical correlation.

Background: Combined injuries observed with first-time lateral patellar dislocation (LPD) of the knee, particularly significant soft tissue injury, can inform surgical intervention criteria.

Purpose: The purpose of this study was to compare MRI findings in LPD to surgical correlation concerning meniscal pathology as a guide for surgical management.

Study Design: Retrospective case series, Level of evidence, 4.

Methods: A retrospective review was conducted of 355 cases of patients with lateral patellar dislocation from 2012 to 2022. Imaging was reviewed by musculoskeletal radiologists blinded to surgical results for evidence of soft tissue injury, and associated arthroscopic data and operative reports were reviewed.

Results: Out of 44 cases of LPD in 42 patients who underwent MPFL reconstructive surgery, 27 (61%) cases had grade 2a or higher signal changes in the anterior horn of the lateral meniscus, of which 10 (23%) had grade 3 signal changes. There were zero cases of meniscal tear in these cases upon review of operative reports and arthroscopic images.

Conclusion: MRI findings of signal alterations in the lateral meniscus post-LPD may not indicate an actual tear. This could aid in surgical decision-making in primary LPD management.