The Effectiveness of a Hinged Elbow Orthosis in Medial Collateral Ligament Injuries: An In Vitro Biomechanical Study
American Journal of Sports Medicine
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© 2019 The Author(s). Background: Medial collateral ligament (MCL) injuries are common after elbow trauma and in overhead throwing athletes. A hinged elbow orthosis (HEO) is often used to protect the elbow from valgus stress early after injury and during early return to play. However, there is minimal evidence regarding the efficacy of these orthoses in controlling instability and their influence on long-term clinical outcomes. Purpose: (1) To quantify the effect of an HEO on elbow stability after simulated MCL injury. (2) To determine whether arm position, forearm rotation, and muscle activation influence the effectiveness of an HEO. Study Design: Controlled laboratory study. Methods: Seven cadaveric upper extremity specimens were tested in a custom simulator that enabled elbow motion via computer-controlled actuators and motors attached to relevant tendons. Specimens were examined in 2 arm positions (dependent, valgus) and 2 forearm positions (pronation, supination) during passive and simulated active elbow flexion while unbraced and then while braced with an HEO. Testing was performed in intact elbows and repeated after simulated MCL injury. An electromagnetic tracking device measured valgus angulation as an indicator of elbow stability. Results: When the arm was dependent, the HEO increased valgus angle with the forearm in pronation (+1.0°± 0.2°, P =.003) and supination (+1.5°± 0.0°, P =.006) during active motion. It had no significant effect on elbow stability during passive motion. In the valgus position, the HEO had no effect on elbow stability during passive or active motion in pronation and supination. With the arm in the valgus position with the HEO, muscle activation reduced instability during pronation (–10.3°± 2.5°, P =.006) but not supination (P =.61). Conclusion: In this in vitro study, this HEO did not enhance mechanical stability when the arm was in the valgus and dependent positions after MCL injury. Clinical Relevance: After MCL injury, an HEO likely does not provide mechanical elbow stability during rehabilitative exercises or when the elbow is subjected to valgus stress such as occurs during throwing.