The influence of type II coronoid fractures, collateral ligament injuries, and surgical repair on the kinematics and stability of the elbow: An in vitro biomechanical study

PurposeThis study determined whether elbow stability could be restored with open reduction and internal fixation (ORIF) of type II coronoid fractures and evaluated the role of collateral ligament repair.MethodsPassive varus and valgus and simulated active vertical motion were performed using an in vitro elbow motion simulator. Varus/valgus angle and internal/external rotation were measured with the coronoid intact, with 50% removed, and after ORIF. Testing was performed with the collateral ligaments detached and repaired.ResultsVertical: stability was normal when both the lateral collateral ligament (LCL) and medial collateral ligament (MCL) were repaired, irrespective of the coronoid state. Kinematics were altered with a repaired LCL, incompetent MCL, and type II coronoid fracture (P < .05). Varus: LCL repair restored coronal stability but did not restore internal rotation (P < .05).ConclusionsThese findings suggest that repair of type II coronoid fractures and injured collateral ligaments should be performed where possible. Over-tensioning the LCL, in the setting of MCL and coronoid deficiency, may contribute to instability.Level of evidenceBasic science study.