Fate of the ulnar nerve after operative fixation of distal humerus fractures.

OBJECTIVES

It is well recognized that operative treatment of a fracture of the distal humerus requires handling of the ulnar nerve, which can cause nerve dysfunction; however, the incidence of postoperative ulnar nerve dysfunction is not well studied. Our purpose was to determine the incidence of ulnar nerve dysfunction after open reduction and internal fixation of distal humerus fractures and identify factors associated with its development.

DESIGN

Retrospective cohort study from two university-based institutions.

PATIENTS: The medical records of 69 patients with a minimum of 12 months follow-up (median, 15 months; range, 12-72 months) after open reduction and plate and screw fixation of a bicolumnar fracture of the distal humerus (Orthopaedic Trauma Association Types 13A and C) that did not have preoperative ulnar nerve dysfunction were reviewed retrospectively.

INTERVENTION: Surgical repair of a distal humerus fracture with or without ulnar nerve transposition.

MAIN OUTCOMES: Ulnar nerve function was graded immediately postoperatively and at final follow-up according to a modified system of McGowan. Those with and without ulnar neuropathy were analyzed for differences in final position of the nerve (anterior versus in the cubital tunnel), open injury, multiple procedures, ipsilateral injury, and demographic factors.

RESULTS

: The incidence of immediately postoperative ulnar nerve dysfunction documented in the medical record was seven of 69 patients (10.1%) (McGowan grades: 1 [57%], 2 [43%], 3 [0%]). The incidence of ulnar nerve dysfunction at final follow-up was 16% (11 of 69 patients) (McGowan grades: 1 [72%], 2 [28%], 3 [0%]). No demographic, injury, or treatment factors were associated with a risk of postoperative ulnar nerve dysfunction.

CONCLUSION

There is a substantial incidence of postoperative ulnar nerve dysfunction after open reduction and plate and screw fixation of the distal humerus, which is likely underestimated by this retrospective analysis. Prospective studies using careful preoperative nerve evaluation and systematic postoperative nerve assessment are likely to identify an even higher incident of postoperative ulnar nerve dysfunction. Transposition was not protective in this analysis.