Isolated displaced type II partial articular radial head fracture: correlation of preoperative imaging with intraoperative findings of lateral ulnar collateral ligament tear.

Background: The aim of this study was to determine the lateral ulnar collateral ligament (LUCL) injury associated with isolated radial head fracture (RHF) and the relationship of the ligament injury with the displacement of the fragment-loss of contact-in unstable displaced partial articular RHF in individuals without any history of ulnohumeral dislocation.

Methods: We retrospectively identified 131 consecutive patients who underwent open reduction and internal fixation of isolated closed Mason type II RHF performed at our institution. We identified 3 subsets by the pattern of RHF and the position of the unstable fragment (anterior or posterior) relative to the capitulum humeri: displaced stable (group I), displaced anterior unstable (group II), and displaced posterior unstable (group III). Standard radiographs were obtained preoperatively and postoperatively. The pattern of lateral collateral ligament avulsion and its distribution were inferred from intraoperative records.

Results: Preoperative radiographs of the 131 patients showed 101 nonseparated fractures (77%, group I) and 30 unstable fractures (23%). Anterior displacement of the fragment was found in 18 elbows (14%, group II) and posterior displacement in 12 (9%, group III). LUCL avulsion was found in 18 of 30 unstable RHFs (60%) and in 1 of 60 stable RHFs (1.6%).

Conclusion: RHF is a complex fracture often associated with soft tissue lesions. It is important to determine which structures need to be repaired to avoid complications that could lead to elbow instability. The RHF pattern and classification as stable or unstable can help the surgeon in the identification and treatment of LUCL lesions.