Fishtail Deformity after Type 2 Supracondylar Humerus Fracture with Development of Symptomatic Loose Body: A Case Report.

Introduction: Supracondylar humerus fractures are one of the most common fractures in children and have been reported to represent up to 16% of all pediatric fractures. While most fractures heal uneventfully with appropriate treatment, there are several known complications that can occur including loss of motion, malunion, and neurovascular injury. One uncommon, yet significant, complication is termed the "Fishtail" deformity. This is represented radiographically with apparent proximal migration of the trochlea, which is thought to be secondary to avascular necrosis and resulting growth arrest. Case Report: This case describes a 11-year-old male who developed a fishtail deformity at age 5, 5 months after percutaneous pinning of a Type II supracondylar humerus fracture. Initially demonstrating a tolerable loss of elbow range of motion (ROM) and being lost to follow-up, he returned 7-years postoperatively, demonstrating diffuse elbow degenerative changes and worsening mechanical symptoms secondary to a loose body which necessitated arthroscopic debridement and loose body removal. Conclusion: This case illustrates the rare fishtail deformity in a Type II supracondylar humerus fracture with acute onset mechanical symptoms of the elbow secondary to a large loose body. Patients with history of supracondylar humerus fractures can develop acute or worsening changes in elbow ROM secondary to the development of osteochondral loose bodies even in the setting of previously known motion deficits secondary to fishtail deformities.