Acute Plastic Deformation of the Forearm Involving Both Bones in an Adolescent: Distinct Deformity Vectors Requiring Individualized Three-Dimensional Correction.

Acute plastic deformation of both the radius and ulna without fracture is rare in adolescents and can be difficult to recognize from initial examination or radiologic assessment. A 16-year-old female sustained a bicycle-related injury and subsequently developed progressive limitation of forearm rotation, prompting reevaluation. Preoperative forearm rotation was restricted to 15 degrees of supination and 60 degrees of pronation, indicating substantial functional impairment. Three-dimensional deformity analysis revealed distinct maximal inclination directions for the radius and ulna, allowing determination of optimal correction angles from the contralateral side. A step-cut osteotomy for the radius and a hinged osteotomy for the ulna achieved adequate correction, supported by intraoperative rotational assessment. At two months postoperatively, forearm rotation had improved to 100 degrees of supination and 90 degrees of pronation, enabling full return to badminton at three months. This case highlights the diagnostic difficulty of acute plastic deformation involving both the radius and ulna within a single forearm and underscores the importance of precise three-dimensional planning in achieving successful correction.