Introduction: Cubitus varus deformity is primarily a cosmetic complaint that causes some early and late complications. However, no studies have reported the cubitus varus deformity regarding the frequency of complications, relationship to the degree of deformity, and period from the occurrence of the initial injury. Methods: Overall, 83 patients with cubitus varus deformity were examined. The differences in the humerus-elbow-wrist angle (triangle HEW-A), tilting angle (triangle TA), and internal rotation angle (triangle IRA) between the affected and normal sides were measured to determine varus and extension and internal rotation deformity. The period from the occurrence of the initial injury to the evaluation date was also investigated. Multivariate logistic regression analysis was conducted to identify the explanatory variables (period, triangle HEW-A, triangle TA, and triangle IRA) independently associated with complication events. Receiver-operating characteristic curve analysis was also conducted to predict the risk of events. Results: triangle HEW-A was independently associated with the risk of cosmetic complaint (odds ratio [OR], 1.171; 95% confidence interval [95% CI], 1.056 to 1.336) and instability (OR, 1.111; 95% CI, 1.028 to 1.200). triangle TA was independently associated with the risk of limited elbow motion (OR, 1.176; 95% CI, 1.077 to 1.285) and sports disability (OR, 0.892; 95% CI, 0.836 to 0.952). The period from the occurrence of the initial injury was independently associated with risk of pain (OR, 1.063; 95% CI, 1.019 to 1.108), ulnar nerve neuropathy (OR, 1.065; 95% CI, 1.011 to 1.125), and osteoarthritis (OR, 1.188; 95% CI, 1.098 to 1.286). The receiver-operating characteristic curve analysis revealed the optimal cutoffs of 20 degrees and 27 degrees for triangle HEW-A to predict cosmetic complaint and instability; of 25 degrees for triangle TA to predict limited elbow motion; and of 8.8, 8.0, and 16.0 years for the period to predict pain, ulnar nerve neuropathy, and osteoarthritis, respectively. Discussion: The treatment of cubitus varus deformity should be determined because a residual deformity >20 degrees of varus and 25 degrees of extension could develop risk of complications over time.
