Relationship of cubitus varus and ulnar varus deformity in supracondylar humeral fractures according to the age at injury

BackgroundWe investigated the relationships of ulnar varus deformity and the degree of cubitus varus according to the age at injury in patients with cubitus varus.MethodsBasic demographic factors were investigated in group 1 (injured at age younger than 5 years) and group 2 (injured at age 5-10 years). The uninjured side ulnar angle (UA) at the time of injury and final follow-up and the humeral-elbow-wrist angle (HEW-A) at final follow-up were measured. ΔUA (injured side – uninjured side UA at final follow-up) and ΔHEW-A (injured side – uninjured side HEW-A at final follow-up) were calculated and compared between the 2 groups. The correlation between ΔUA and ΔHEW-A was analyzed, and the degree of correlation was compared between the groups.ResultsFinal UA and HEW-A on the injured side were increased more in group 1. ΔUA and ΔHEW-A were also more definitive in group 1. Positive correlations were found in both groups between ΔUA and ΔHEW-A, and the degree of correlation was similar in both groups. Distinct negative correlations were observed in both groups between the uninjured side UA at the time of injury and the ΔUA, but the degree of correlation differed significantly.ConclusionsThe degree of ulnar varus correlated well with the degree of cubitus varus. A straighter ulna at the time of injury could become more bowed if cubitus varus deformity occurred and progressed. This may be evidence suggesting that the earlier correction of cubitus varus would be more effective under a less deformed varus of the ulna.Level of evidenceLevel III; Retrospective Cohort Design; Treatment Study