6 – DYNAMIC MR IMAGING WITH CONCURRENT PHYSICAL EXAMINATION IN EVALUATION OF KNEE MCL INJURIES

Abstract

Purpose: In evaluating injury severity of acute medial collateral ligament (MCL) injuries, the current standard is to perform a history and physical examination and static MRI of the injured joint. With recent advances in dynamic MR imaging technology, we hypothesized that concurrent physical examination and dynamic MRI of the knee joint in patients with acute MCL injuries is feasible and would provide new insight into the injured joint kinematics while correlating to clinical and diagnostic imaging criteria for injury severity.

Method: 10 patients (5 male, 5 female) with isolated, unilateral, acute MCL injuries were prospectively enrolled in the study. An orthopedic surgeon performed initial physical examination and clinical grading. Dynamic MRI with concurrent physical examination was performed in a 1.5T wide-bore magnet and compared to the uninjured knee as a control. The dynamic MR imaging data was compared with morphologic MCL changes on static MRI, with dynamic examination of the contralateral knee and with the clinical grading of MCL injury. The width of the medial joint space and the opening angle between the femur and tibia were measured.

Results: Clinically, one patient had grade 1 and nine had grade 2 injuries. Using morphologic MRI criteria there were nine grade 2 and one grade 3 injuries. Mean and median medial opening angles of all affected knees was 2.8/2.5 mm and 2.8/2.6°, respectively, as compared to 1.8/1.8 mm and 2.2/2.1° in the normal side. Measurements of medial joint-space opening showed little quantitative difference between grade 1, 2 and 3 injuries. Interobserver agreement (intraclass correlation coefficients) varied from 0.9 to 0.93.

Conclusion: Dynamic MR imaging with concurrent physical examination is feasible and correlates to clinical and morphologic grading of severity. Our study suggests that traditional clinical grading systems of MCL injuries overestimate medial joint space opening.