P0854 - Risk factors associated with nerve palsy in operatively treated supracondylar humerus fractures in the pediatric population.

Background/Purpose: Nerve injuries are frequently associated with displaced supracondylar humerus fractures (SCHF). A high index of suspicion for nerve palsy is essential in children who can be notoriously difficult to examine. We hypothesize nerve injuries are more prevalent in higher energy type III and flexion type SCHF compared with type II. The secondary aim is to evaluate risk factors associated with nerve palsy in operatively treated SCH fractures.

Methods: A retrospective review of 1085 operatively treated SCHF in pediatric patients aged 0-14 years old between January 1, 2015 and December 31, 2018. 979 patients were eligible for analysis. Exclusion criteria include follow-up less than 3 weeks, polytrauma, and prior fracture of the ipsilateral elbow.

Results: The overall rate of nerve palsy was 10.6% (104/979). There was a significant difference in the rate of nerve palsy between fracture types: 0.9% Type II, 19.3% Type III, and 10.7% flexion type SCHF (p<0.001). Median nerve palsy was most commonly associated with type III SCHF whereas an increased rate of ulnar nerve palsy was observed in flexion type fractures (Table 1). In patients who received a medial pin, the rate of post-operative nerve palsy was 15% versus 10% in the lateral only pin group (p=0.0345). The medial pin group experienced both AIN (p=0.005) and ulnar nerve palsies (p=0.0421). Of the 104 patients with post-operative nerve palsy, 84 (81%) had a documented pre-operative nerve deficit compared to 20 children (19%) with a reportedly normal exam prior to surgery. Of these 20 children, only 3 patients received a medial pin with no statistically significant association to ulnar nerve injury. In type III and flexion SCHF, longer operative times (> 60 minutes) were found to be associated with a higher rate of nerve palsy, (30% vs. 17%; p=0.0234). Finally, nerve palsy was associated with the need for open reduction (p=0.0118) of the fracture.

Conclusion: The majority of patients with a post-operative nerve palsy had abnormalities on pre-operative examination (81%). The remaining 19% of the patients, who were not noted to have neurologic deficits until post-operative examination, highlights the challenges with examining children, particularly in the setting of an acute, displaced fracture. The association between increased rates of nerve palsy with a higher grade of injury (type III or flexion SCHF), longer operative times, and open reduction is likely related to the severity of soft tissue injury associated with these fractures. Although medial pin placement was associated with post-operative nerve palsy, which included both AIN and ulnar nerves, there was no significant association between medial pin insertion and ulnar nerve injury. It can thus be concluded that the greater degree of soft tissue trauma encountered in displaced and unstable SCHF leads to nerve palsy rather than iatrogenic causes.