Radiological anatomy and injuries of the condylar strap and Kaplan fibers associated with ACL pathology

Abstract

Objectives: The study aimed to identify the Kaplan fiber (KF) complex, focusing on the condylar strap (CS) which are fiber straps on the lateral aspect of the knee related to the iliotibital complex, on magnetic resonance imaging (MRI) of knees performed for acute anterior cruciate ligament (ACL) injury, measure the distances of insertion from the lateral joint line, and identify injuries to these structures. Material and Methods: Retrospective analysis of 134 MRIs of knees with acute ACL tear was performed. The proximal and distal KFs and the CS were identified on at least one plane on MRI. The distance of their femoral attachment from the lateral joint line and injury to these structures with concomitant knee injuries was documented. Data analysis was performed using the SPSS software. Results: KFs were identified in 97.2% and CS in 72% of the MRI knees. The mean distance of the proximal KF from the lateral joint line was 59.1 mm, while that of the distal KF was 42.4 mm. The CS attached 35.6 mm proximal to the lateral joint line. KF complex injury was present in 34% of cases with ACL tear. The MRI finding of meniscal tear and bone marrow edema in a classic pivot shift impaction injury pattern had a significant positive correlation with KF injury. Conclusion: This radiological study confirms the existence of CS on MRI. There is a positive association of KF injury with meniscal tears and bone marrow edema in patients with acute ACL tears. Future biomechanical studies focusing on CS are needed to identify its contribution to anterolateral stability.