Incidence and Risk Factors of Ulnar Neuropathy After the Surgical Treatment of Distal Humeral Fractures

One of the major complications associated with open reduction and internal fixation (ORIF) for distal humeral fractures is ulnar neuropathy. However, varying reports on its incidence have led to inconsistent opinions. This study aimed to investigate the incidence of ulnar neuropathy in patients who underwent open reduction and internal fixation using two precontoured anatomical locking plates for distal humeral fractures at our hospital. Additionally, we aimed to examine the symptoms and progression of ulnar neuropathy in these cases.

Among patients who underwent surgery between February 2012 and February 2022, 40 patients with a follow-up period of ≥3 months were included. Fractures were categorized in accordance with the AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification as follows: A2 (n=17), A3 (n=1), C1 (n=17), or C2 (n=5). We retrospectively compared the incidence of postoperative ulnar neuropathy and its symptom severity between Group A (types A2 and A3) and Group C (types C1 and C2). Furthermore, we compared the incidence of neuropathy between groups that did versus did not develop neuropathy.

The incidence of ulnar neuropathy was 35% (14/40 patients), including one patient with concurrent radial neuropathy. Group A had a significantly higher incidence of ulnar neuropathy compared with Group C. Among patients who developed neuropathy, the condition resolved in seven during the study period, while seven remained symptomatic. All patients with persistent symptoms had type C1 fractures. Additionally, a comparison of age between the neuropathy and non-neuropathy groups showed a statistically significant predominance of neuropathy in patients <65 years of age.

Ulnar neuropathy occurred more frequently with distal humeral fractures in patients <65 years of age. Furthermore, the incidence of ulnar neuropathy was significantly higher with intra-articular fractures, suggesting a tendency for persistent symptoms with these fractures.