Predictors of diagnosis of ulnar neuropathy after surgically treated distal humerus fractures.

PURPOSE: Ulnar nerve dysfunction is a common sequela of surgical treatment of distal humerus fractures. This study addresses the null hypothesis that different types of distal humerus injuries have comparable rates of diagnosis of ulnar neuropathy.
METHODS: We assessed diagnosis of ulnar neuropathy in 107 consecutive adults who had a surgically treated fracture of the distal humerus followed up at least 6 months after injury. Diagnosis of ulnar neuropathy was defined as documentation of sensory and motor dysfunction of the ulnar nerve in the medical record. Fractures were categorized as either columnar fractures or fractures of the capitellum and trochlea. The explanatory (independent) variables included age, sex, fracture type, AO type, associated wound, associated elbow dislocation, mechanism of trauma, ipsilateral skeletal injury, olecranon osteotomy, implant over or below the medial epicondyle, infection, time from injury to surgery, the number of surgeries within 4 weeks and 6 months of injury, the total number of surgeries, and whether the nerve was transposed.
RESULTS: Postoperative ulnar neuropathy was diagnosed in 17 of 107 patients (16%), including 16 of 59 columnar fractures (21%). The only risk factor for ulnar neuropathy was columnar fracture.
CONCLUSIONS: Patients with columnar fractures might be at higher risk for the development of postoperative ulnar neuropathy than patients with capitellum and trochlea fractures, regardless of whether the ulnar nerve was transposed. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.