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

PURPOSE: This 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. METHODS: Passive 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. RESULTS: Vertical: 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). CONCLUSIONS: These 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.