Wrapping of the Medial Ulnar Collateral Ligament

The multi-bundle structure of the medial ulnar collateral ligament (mUCL) has been documented [1] and it is known that the anterior bundle of the mUCL is the primary restraint to valgus stress of the elbow [2–5]. It has also been documented that the anterior band of this bundle becomes taut in extension whereas the posterior band becomes taut in flexion [1]. The mUCL is frequently injured in the throwing athlete due to over use or extreme valgus load. In order to reconstruct the ligament, surgical repair may be required. It has been experimentally observed in our lab and in other labs that the UCL wraps around the medial epicondyle. One of the parameters to ensure achievement of a successful surgical reconstruction may be the re-establishment of the natural wrapping behavior of UCL around the epicondyle. Previous studies [6] also suggest that soft-tissue wrapping constraints have substantial impact on joint stability. This study begins to characterize the wrapping of the two bands in the anterior bundle of UCL in terms of the location along the ligament’s length and flexion angle to establish native behavior.