Description
Objectives: To reveal the relationship between Magnetic Resonance Imaging (MRI) and physical examination (PE) findings in patients with acute anterior cruciate ligament (ACL) injuries.
Methods: Twenty-seven patients with a diagnosis of acute ACL tear who had a complete set of MRIs obtained within 3 weeks and examination findings within 3 months after injury were included in this retrospective study. Patients whose MRI images were not sufficient for evaluation and those with multiple ligament injuries were excluded. Sports type, injury mechanism, and PE findings including local tenderness area, range of motion and laxities were noted. Laxity examinations of patients were repeated under anesthesia prior to surgery. MRI were analyzed by two independent musculoskeletal radiologists who were blind to PE findings. MRI sections were evaluated to search for the integrity of anterolateral ligament (ALL) and Kaplan fibers (Figures 1&2); if torn location of the tear was noted along with associated injuries. Statistical analyses were performed utilizing SPSS v21, and the relationship between categorical data was examined with the Pearson Chi-Square test. Significance level was set at 0.05. Inter-observer consistency between two radiologists' findings was evaluated with Cohen’s Kappa value.
Results: Mean age was 26.3±8.4 years old. Sports and injury characteristics, PE findings were presented in Tables 1&2. PE revealed that 16 patients had grade 1, 8 had grade 2, and 3 had grade 3 pivot shift test positivity. Over MRI sections, 20 patients (74.7%) had ALL injuries six (22.2%) which was partial, 14 (51.9%) total. Of the 15 patients with Kaplan fibers damage, 8 had edema (29.6%), 5 had partial (18.5%) and 2 (7.4%) had total rupture. One patient (3.7%) presented with Segond fracture, while 3 had (11.1%) lateral meniscus root tears and 15 (55.6%) had RAMP lesions. There was almost perfect interobserver agreement of radiologists for the presence of ALL injury (κ=0.908) and substantial interobserver agreement for the presence of Kaplan fiber injury (κ=0.780). No statistically significant correlation was found between the degree of pivot shift test and presence of either ALL injury (p = 0.638) or Kaplan fiber injuries (p = 0.257) (Table 3). There was not a statistically significant correlation between lateral side tenderness in the early post-injury physical examination and Kaplan fiber damage (p=0.259), or between lateral side tenderness and presence of ALL injury (p=0.636).
Conclusions: ALL injury is present on MRI in most ACL injuries, but it is not associated with clinical findings such as high-grade pivot shift test, Lachman test, and anterior drawer test.
