Transphyseal Separation of the Distal Humerus in a 5-Year-Old Child: A Rare Case Report.

Background: Transphyseal separation of the distal humerus (TSDH) is an uncommon injury, typically seen in children under 3 years of age, with very few cases reported beyond this age group. Diagnosing this injury is challenging due to its cartilaginous nature. TSDH in infants is commonly treated with manual reduction and long-arm cast application; however, a few case series have suggested that surgical treatment may be a better option in older children. Case Summary: A 5-year-old boy presented with left elbow swelling and restricted movements after a fall on an outstretched hand 2 days earlier. On physical examination, the three-point bony relationship was maintained, and the distal neurovascular status was intact. Radiographs of the left elbow joint showed posteromedial displacement of the radioulnar complex with maintained radio-capitellar line. The TSDH was suspected, and intraoperative arthrography was planned. The diagnosis of TSDH was confirmed intraoperatively with the aid of arthrography. The patient underwent closed reduction and percutaneous K-wire fixation after confirming optimal alignment. Postoperatively, the elbow was immobilized using an above-elbow posterior slab. At 5 weeks, the slab was removed, and gradual range-of-motion exercises were initiated. At the 2-month follow-up, the child had a satisfactory range of motion. At the 15-month follow-up, the patient demonstrated an excellent, pain-free range of motion with no residual deformity or radiographic abnormalities. Conclusion: The TSDH in older children is a rare entity. The accurate reduction and timely diagnosis should be given priority so as to avoid late complications. If appropriate intervention is done ensuring adequate reduction and stable fixation, even with limited resources, excellent results can be achieved in such challenging cases.