The Ulnar Collateral Ligament is Always Torn in the Posterolateral Elbow Dislocation: A Suggestion on the new Mechanism of Dislocation Using MRI Findings

Abstract

PURPOSE: From the status of ulnar collateral ligament of elbow with magnetic resonance image which suffered with posterolateral dislocation. We would propose the novel mechanism of posterolateral elbow dislocation.MATERIALS AND METHODS: Between November 2005 and October 2009, we prospectively collected 12 cases of simple posterolateral elbow dislocation. The location of bone contusion and the status of collateral ligament were evaluated with MRI. Collateral ligament was divided in 2 subgroups (distraction type, stripping type). We also defined the disengagement as escaping of conoid process from trochlear notch totally.RESULTS: From 12 cases, we could found 11 cases of bone contusion in radial head or capitellum. Trochlea and conoid process were always intact without bone contusion. All ulnar collateral ligament ruptures were distraction type instead of all lateral collateral ligament ruptures were stripping type. Translations of all cases were shown those of the ulnar collateral ligament were longer than those of lateral collateral ligament (p<0.05).CONCLUSION: We carefully conclude that UCL and surrounding soft tissue has responsibility for the initiation of simple posterolateral elbow dislocation.