A Pediatric Case of Cubitus Varus Deformity due to Olecranon Fracture.

We encountered a pediatric case of cubitus varus deformity with a sheared olecranon fracture in an 8-year-old boy who underwent corrective osteotomy without relevant medical history. The patient fell, resulting in a sheared olecranon fracture. He underwent a closed reduction and casting. As the displacement slightly increased within a week, we followed him without secondary reduction to expect remodeling. No remodeling occurred; corrective osteotomy was performed one-year post-injury for a marked cubitus varus deformity. At 2.5 years after corrective osteotomy, little difference existed in the carrying angle (CA) and varus angulation (VA) of the proximal ulna than that of the contralateral side, without pain or limited range of motion. The acceptable displacement range for pediatric forearm fractures is <1 cm shortening and 15° angular deformation in patients under 10 years old, and 10° angular deformation in older children. Here, the deformity of the ulna in the coronal plane did not remodel. Proximal forearm deformity can be accurately evaluated in flexion contracture elbows by measuring VA. Ulnar osteotomies are commonly performed on Monteggia fractures to reduce the radial head, and the osteotomy site is at the center of the deformity of the diaphysis. Corrective osteotomy for cubitus varus deformity after supracondylar humerus fracture improves function and cosmetic appearance, with good clinical results. In addition, it could prevent cubitus varus deformity from causing posterolateral rotatory instability. The coronal-plane deformity of the proximal ulnar was not expected to remodel. We recommended early accurate reduction and consideration of additional internal fixation for preventing re-displacement. Corrective osteotomy for cubitus varus deformity of the proximal ulna was an effective treatment.