Background: Supracondylar fractures of the humerus are the most common type of elbow fracture in children. Of all complications associated with supracondylar fractures, nerve injury ranks highest, although reports of the incidence of specific neurapraxia vary. This meta-analysis aims primarily to determine the risk of traumatic neurapraxia in extension-type supracondylar fractures as compared with that of flexion-type fractures; secondarily it aims to use subgroup analysis to assess the risk of iatrogenic neurapraxia induced by pin fixation.
Methods: A literature search identified studies that reported the incidence of nerve injury presenting with displaced supracondylar fractures of the humerus in children. Meta-analysis was subsequently performed to evaluate the risk of traumatic neurapraxia associated with supracondylar fractures. Subgroup analysis of included articles was additionally performed to assess the risk of iatrogenic neurapraxia associated with lateral-only or medial/lateral pin fixation.
Results: Data from 5148 patients with 5154 fractures were pooled for meta-analysis. Among these patients, traumatic neurapraxia occurred at a weighted event rate of 11.3%. Anterior interosseous nerve injury predominated in extension-type fractures, representing 34.1% of associated neurapraxias; meanwhile, ulnar neuropathy occurred most frequently in flexion-type injuries, representing 91.3% of associated neurapraxias. Nerve injury induced by lateral-only pinning occurred at a weighted event rate of 3.4%, while the introduction of a medial pin elicited neurapraxia at a weighted event rate of 4.1%. Lateral pinning carried increased risk of median neuropathy, whereas the use of a medial pin significantly increased the risk of ulnar nerve injury.
Conclusions: Of nerve injury associated with extension-type fractures, anterior interosseous neurapraxia ranks highest, whereas of flexion-type neuropathy, ulnar nerve injury predominates. We confirm that medial pinning carries the greater overall risk of nerve injury as compared with lateral-only pinning and that the ulnar nerve is at risk of injury in medially pinned patients. We additionally suggest that lateral pinning carries neurapraxic risk with respect to the median nerve.
Level of Evidence: Level IV; Meta-analysis.