Sensitivity of MRI reports for ligamentous injuries in high-grade knee dislocations: A single-center retrospective analysis of radiology reports and operative findings

Introduction: Knee dislocations, particularly high-grade injuries such as Schenck class KDIV, are complex injuries often resulting from high-energy trauma. While magnetic resonance imaging (MRI) is widely used preoperatively to assess ligamentous damage, its diagnostic accuracy remains uncertain. Methods: A retrospective review was conducted on 92 patients who underwent surgery for a knee dislocation at a Level I trauma center over 10 years. Patients who had a preoperative MRI report and intraoperative confirmation of a KDIV injury without a tibial plateau fracture were included, which left 31 patients. MRI sensitivity was determined by comparing radiology reports to operative findings with fluoroscopic examination under anesthesia (EUA) for injuries to the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), and posterolateral corner (PLC). Postoperative follow-up documents were reviewed for functional outcomes. A one-way analysis of variance (ANOVA) was performed to evaluate differences in sensitivity across ligament types, followed by a Tukey post hoc test for pairwise comparisons. Mean flexion ROM at final follow-up (≥6 months) was compared between the accurate and inaccurate MRI cohorts using an independent t-test. Results: Only 35.5% of MRI reports fully matched operative findings. MRI sensitivity was 71.0% for the ACL (22/31), 61.3% for the PCL (19/31), 93.5% for the MCL (29/31), 64.5% for the LCL (20/31), and 51.6% for the PLC (16/31). ANOVA revealed that MCL sensitivity was significantly higher than that of the PLC, PCL, and LCL. The difference in mean flexion ROM at final follow-up between accurate and inaccurate MRI cohorts was not statistically significant (p = 0.56). Discussion: Preoperative MRI radiology reports demonstrated substantial limitations in accurately identifying ligamentous injuries in KDIV knee dislocations, particularly involving the PLC, PCL, and LCL. These findings highlight a gap between radiologic interpretation and surgical findings. Surgeons should interpret MRI reports with caution and incorporate fluoroscopic EUA at the time of surgery to ensure a comprehensive assessment of ligamentous damage.