Fracture characteristics in coronal shear fractures of the distal humerus: Clinical significance of medial trochlear involvement.

BACKGROUND: Coronal shear fractures of the distal humerus exhibit diverse fracture-extension patterns that are not fully characterized by conventional classification systems. The clinical significance of fracture extension into the medial or lateral column remains incompletely understood. This study investigated fracture-extension patterns beyond the conventional Dubberley classification and evaluated their associations with clinical outcomes and bone-related complications.

METHODS: This multicenter retrospective study included surgically treated coronal shear fractures of the distal humerus with a minimum follow-up of 12 months at four affiliated institutions between 2012 and 2024. Fractures were classified using the AO/OTA and Dubberley systems. Computed tomography (CT) images were reviewed to assess medial trochlear involvement, lateral column involvement without posterior condylar comminution, and isolated trochlear fractures. Clinical outcomes included elbow range of motion (flexion, extension, and arc of motion) and postoperative complications. Univariate logistic regression analysis was performed to identify factors associated with bone-related complications.

RESULTS: Among 374 surgically treated distal humeral fractures, 35 coronal shear fractures were included in the final analysis. Medial trochlear involvement was identified in 8 fractures (23%) and was most frequently observed in Dubberley type 3 fractures. Patients with medial trochlear involvement had significantly greater loss of elbow extension at final follow-up than those without medial trochlear involvement (-29° vs. -16°, P = 0.042). Bone-related complications were more frequent in fractures with medial trochlear involvement than in those without (50% vs. 7%, P = 0.016). In univariate logistic regression analysis, medial trochlear involvement was significantly associated with bone-related complications (odds ratio, 12.5; 95% confidence interval, 1.69-92.3; P = 0.013). Neither the AO/OTA nor the Dubberley classification was significantly associated with bone-related complications.

CONCLUSIONS: Medial trochlear involvement was significantly associated with greater loss of elbow extension and bone-related complications at final follow-up in coronal shear fractures of the distal humerus. Preoperative CT assessment of medial trochlear involvement may provide clinically useful information complementary to conventional fracture classification systems and may aid surgical planning.