Fracture-Separation of the Medial Humeral Epicondyle Caused by Arm Wrestling: A Systematic Review

Abstract

Background: Arm wrestling is a popular sport in which various injuries have occurred, even in children.

Purpose: To analyze reported fracture-separation of the medial humeral epicondyle (MHE) caused by arm wrestling to determine its mechanism and provide a current overview.

Study design: Systematic review; Level of evidence, 4.

Methods: The PubMed and Web of Science databases were searched using the terms "arm wrestling" and "humeral fracture" or "medial humeral epicondyle fracture"; and "sports" and "humeral fracture" or "medial humeral epicondyle fracture," following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The inclusion criteria were English full-text articles on arm wrestling-induced MHE fracture that described patient characteristics and presented appropriate images. Studies with a lack of appropriate images or detailed description of the injury situation were excluded. The patient characteristics were evaluated, and the ratios of treatment selection and outcomes were evaluated using the chi-square test.

Results: Included were 27 studies with a total of 68 patients, all boys with a mean age of 14.6 ± 1.24 years (based on n = 65, with 3 patients excluded from this calculation as no definitive age was provided). Boys aged 14 to 15 years accounted for 72% (49/68) of the cases. Fracture occurred suddenly during arm wrestling in 63 boys, while the other 5 boys experienced antecedent medial elbow pain. The match status at the time of injury, provided for 46 patients, was varied. In 31 boys with known match details, injury occurred when a participant suddenly added more force to change the match status. Eight patients displayed anterior and/or proximal displacement of the MHE fragment. Treatment was nonoperative in 25 patients and operative in 38 patients (n = 63, excluding 5 unknown patients). In 35 patients followed up for ≥3 months (mean, 17.6 ± 12.3 months), outcomes were not significantly different between the operative and nonoperative groups.

Conclusion: MHE fracture-separation caused by arm wrestling occurred mostly in boys aged 14 to 15 years regardless of the match status. The likely direct cause is forceful traction of the attached flexor-pronator muscles. A relative mechanical imbalance during adolescence may be an underlying cause. A sudden change from concentric to eccentric contraction of the flexor-pronator muscles increases the likelihood of fracture occurrence.

Keywords: adolescence; arm wrestling; avulsion fracture; medial humeral epicondyle.

Figure 1.

The flexor-pronator muscle complex originates from the medial humeral epicondyle. The anterior bundle of the ulnar collateral ligament complex is present behind these muscles.

Figure 2.

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart of the study selection process.

Figure 3.

Age distribution of patients with medial humeral epicondylar fracture-separation.

Figure 4.

Displacement of the medial humeral epicondylar (MHE) fracture fragment (arrows indicate direction of traction by the attached muscles). (A) When the elbow is in the extended position at the time of injury, the MHE fragment displaces toward the distal and slightly toward the anterior. (B) When the elbow is in the flexed position, the posteriorly located MHE fragment displaces anteriorly after going around the anterior edge of the metaphysis.