Limited Agreement on ACL Tear Location Between Arthroscopy and MRI: A Prospective Evaluation
Richard Silverman1, Derrick M Knapik1, Matthew V Smith1
1Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA.
Background:
Renewed interest in anterior cruciate ligament (ACL) preservation has led to increased focus on tear location within the knee joint in treatment decisions, with primary ACL repair reserved for proximal tears. Retrospective studies have reported varying tear locations in adults when assessed on magnetic resonance imaging (MRI), with few studies comparing tear location on MRI versus intraoperative findings.
Purpose:
To prospectively determine the distribution of ACL tear location assessed on MRI versus intraoperative evaluation to test the hypothesis that <15% of ACL tears are proximal type avulsions.
Study Design:
Cohort study (Diagnosis); Level of evidence, 2.
Methods:
A total of 174 patients with clinically confirmed full-thickness ACL tears between August 2022 and March 2024 were identified and enrolled. Patients with partial tears, chronic injuries, recurrent ACL tears, or multiligamentous injuries were excluded. ACL tear locations were classified on preoperative MRI and intraoperatively using the modified Sherman classification. Patient demographic characteristics, injury mechanism, and surgical details were recorded. Analysis of variance and chi-square and Fisher exact tests were used for analysis, with significance set at P < .05.
Results:
ACL tear location based on MRI was as follows: 9.8% type I, 22.4% type II, 67.2% type III, and 0.60% type IV, with no type V tears. Arthroscopic tear location distribution was as follows: 26.4% type I (proximal avulsion), 44.8% type II (proximal), 25.8% type III (midsubstance), and 3.4% type IV (distal), with no type V tears. There was 43% agreement between arthroscopic and MRI evaluation overall, with 95.5% agreement when classifying type III tears. Type I tears were more common in older patients, whereas type III tears were more common in younger patients. No significant correlations were appreciated based on patient sex, body mass index, or injury mechanism.
Conclusion:
Poor agreement was found between imaging and arthroscopic assessment of ACL tear location, as MRI predicted intraoperative ACL tear location in less than half of cases. However, very good agreement was noted when classifying type III tears. Tear pattern was associated with patient age, with more type I tears in older patients and more type III tears in younger patients.
