Risk of Fragments in Ulnar Collateral Ligament Injuries Of Baseball Players

OBJECTIVES: Many baseball players with UCL injuries have avulsed persistent fragments by throwing disorder in the youth. The presence of fragments results in discontinuity of the medial elbow joint support structures; therefore, a ligament with fragments is considered more fragile than the normal ligament. This study compared three types (fragment, malunion, and normal) of throwing-related UCL injuries and prospectively examined the risk of surgical treatment. METHODS: The total subjects were 439 baseball players (age 14-30 years; mean age, 17.5 years) diagnosed with UCL injuries at our hospital between November 2009 and June 2013. At the time of the initial examination, the medial epicondyle was assessed on plain frontal radiographs with the elbow flexed at 45°. Based on this assessment, subjects were divided into three groups: group with persistent fragments (fragment [F] group), group with complete union following avulsion fracture (malunion [M] group), and a group with no history of avulsion fracture (normal [N] group). Each patient’s ability to return to playing baseball was assessed after at least 3 months of systematic rehabilitation. Subjects who failed to comply with rehabilitation, played only recreationally, or with pain in sites other than the elbow were excluded. In this series, 220 cases were left for investigation. The Conway-Jobe scale was used as a standard to assess the return to playing after conservative therapy; subjects with excellent or good ratings were deemed able to return to playing baseball, whereas those with fair or poor ratings were deemed unable to return to playing baseball. The return rates were calculated for the F, M, and N groups respectively. The Magnetic resonance (MR) images consisted of three slices along the long axis of the anterior oblique ligament; these images were used to classify injuries as severe or mild, which were then compared with each other. SPSS 20.0 was used to perform the statistical analysis. RESULTS: A total of 107 subjects were able to resume playing competitive baseball game, whereas 113 subjects were unable to resume playing and underwent surgical treatment (Table.1). The F group demonstrated a significantly lower return rate (p < 0.01) (Table.2). The F group demonstrated a significantly higher percentage of severe injuries (p < 0.01) (Table.2).Return rates in the mild and severe injury groups were 79.1% and 29.1%, respectively, demonstrating a significant difference (p < 0.01) (Table.3). Not surprisingly, the return rate among subjects with severe injuries in the F group was a mere 14.3% (7/49). CONCLUSION: The results of the present study demonstrated that the presence of fragments in UCL injuries tended to increase the severity of UCL injuries and significantly reduced patient the return rates of competitive game after conservative therapy. Therefore, this exacerbation of UCL injuries is considered a result of persistent medial epicondylar fragments in young baseball players.