Abstract
Objectives:
Anterior cruciate ligament (ACL) injuries are reliably diagnosed through MRI and clinical examination. However, concomitant injuries such as anterolateral ligament (ALL) tears pose challenges for accurate assessment. Additionally, while the pivot-shift test effectively evaluates anterolateral rotatory laxity, its assessment may be hindered by patient discomfort during medical office evaluations, particularly in the acute phase. This study aimed to evaluate whether tibiofemoral rotation was associated with a concurrent ALL injury and pivot-shift grading in patients with a primary ACL tear.
Methods:
In this multicenter cross-sectional study, constituting a secondary analysis of previous studies, medical records and MRI scans of patients with unilateral primary ACL injury were reviewed. Demographics and pivot-shift grading were collected. Anterolateral ligament was identified on MRI coronal images and classified as intact or injured. Tibiofemoral rotation angle (TFA) was measured on axial MRI. Optimal TFA cutoff associated with ALL injury was identified by a receiver operating characteristic (ROC) curve.
Results:
A total of 206 patients were included, with a mean age of 28.3 ± 11.3 years. Among them, 152 (73.8%) exhibited signs of ALL injury. Pivot-shift tests were predominantly graded as 2 (71.4%), and notably, all grade 3 pivot-shift assessments were associated with ALL injury. The mean TFA was 4.5 ± 3.8 degrees, significantly higher in cases with ALL injury (5.2 ± 3.6 degrees) compared to intact ALL cases (2.7 ± 3.5 degrees; p < 0.001). A positive correlation was observed between pivot-shift grading and TFA (r = 0.204, p = 0.003). Optimal TFA cutoff value to predict ALL injury was 2.5 degrees (sensitivity 0.77; specificity 0.55). Patients with TFA angles at or above 2.5 degrees exhibited an increased likelihood of ALL injury compared to those below it (OR 3.34 - 95% CI: 1.74 to 6.42, p < 0.001). Interestingly, when TFA equal to or greater than 2.5 is combined with pivot-shift grade 2 or 3, the likelihood of ALL injury increased substantially to 13.68 (95% CI: 6.29 to 29.84, p < 0.001).
Conclusions:
Higher TFA was associated with an increased prevalence of ALL injuries and a high-grade pivot-shift in ACL-deficient patients. Patients with a TFA ≥ 2.5 degrees showed a 3-fold higher likelihood of ALL injuries at the time of ACL injury, and this risk further escalated with a higher-grade pivot-shift. Thus, assessing TFA in ACL reconstruction patients can guide decisions for concomitant anterolateral reconstruction, particularly in the presence of a high-grade pivot-shift.
