Keywords:
Performed at one institution, Observational, Retrospective, Athletic injuries, Comparative studies, MR, Musculoskeletal joint, Extremities, Musculoskeletal
Authors:
W. C. W. Tsui, K. K. Cheng; Hong Kong/HK
DOI:
10.26044/ecr2020/C-08610
Purpose
Anterior cruciate ligament (ACL) tear is a commonly encountered injury, with about 250,000 cases reported yearly in the USA alone [1]. The ACL acts as an important knee stabilizer, such that injury to this structure leads to substantial knee instability. Magnetic resonance imaging (MRI) has been the imaging staple for evaluation of the ACL and other internal derangements of the knee. Multiple imaging features have been described to diagnose direct and indirect features of ACL tear. Detection of indirect features of ACL tear can help to improve diagnostic accuracy particularly when the ACL is not entirely visualized in a single sagittal section [2].
The ACL functions to prevent abnormal anterior translation of the knee during extension as well as to provide rotational stability [3]. Anterior tibial translation is described as 7mm or greater anterior tibial translocation relative to the femur [4]. Anterior tibial translation is associated with a number of secondary features including posterior cruciate ligament (PCL) buckling, patellar tendon buckling, or uncovering of the posterior horn of the medial or lateral menisci [3].
The wavy patellar tendon sign is a recently described indirect sign of ACL injury with a reported sensitivity of 82%, specificity of 80%, and diagnostic accuracy of 81% [5]. On sagittal view, the patellar tendon appears as a wavy or undulating appearance when the sign is present.
In this study, we evaluate the wavy patellar tendon sign as an indirect sign of ACL injury and its association with complete tears of the ACL. We examined the frequency of the wavy patellar tendon sign seen in patients with complete ACL tears. The degree of anterior tibial translation that is associated with the presence of a wavy patellar tendon compared to those without a wavy patellar tendon in ruptured ACL knees were evaluated.