Poster 351: Influence of Injury to the Kaplan Fibers and Anterolateral Ligament on Anterolateral Rotatory Knee Laxity in Adult and Pediatric Patients with Anterior Cruciate Ligament Injury: A Retrospective Cohort Study

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Abstract

Objectives: To detect concomitant Kaplan fibers (KF) and anterolateral ligament (ALL) injury in knees with anterior cruciate ligament (ACL) injury using magnetic resonance imaging (MRI) in both adult and pediatric patients and compare the effect of KF injury and multiple risk factors (concomitant injury to the ALL, medial collateral ligament [MCL], or anterior, central, or posterior part of the medial or lateral meniscus) on anterolateral rotatory laxity as measured by the pivot-shift test in a clinical setting. Methods: The study included 540 patients with primary ACL tears (71 pediatric patients and 469 adults) whose MRI examination and pivot-shift test were conducted within 14 days after injury. KF and ALL injury were assessed by MRI according to previously reported criteria. At the time of ACL reconstruction, the pivot-shift test was performed manually with the patient under anesthesia. Manual grading of the pivot shift was performed according to guidelines of the International Knee Documentation Committee (IKDC). Data were statistically compared between the adult and pediatric groups using the chi-square test and Fisher’s exact test (p < 0.05). Results:  Logistic regression analysis with backward elimination was used to identify risk factors associated with a high-grade pivot shift. Of the 12 initially included predictive variables, only four significantly increased the risk of a high-grade pivot shift: sex (odds ratio: 2.268 in total and 2.248 in adults), ALL disruption (odds ratio: 0.488 in total and 0.445 in adults), KF injury (odds ratio: 0.193 in pediatric patients), and injury to the posterior horn of the lateral meniscus (odds ratio: 0.545 in total and 0.559 in adults). Logistic regression analysis with backward elimination was also used to identify risk factors associated with KF injury. Of the 3 initially included predictive variables, 2 significantly increased the risk of KF injury: ALL injury (odds ratio: 0.271 in total and 0.206 in adults) and ALL disruption (odds ratio 0.267 in pediatric patients, odds ratio 0.580 in adults and 0.552 in total). Conclusions: Concomitant KF injury significantly affects the pivot-shift phenomenon in pediatric patients with acute ACL injury. These findings suggest that KFs may play an important role in controlling anterolateral rotatory knee laxity in pediatric patients.