Neonatal separation of the distal humeral epiphysis can be treated orthopedically without reduction.

Background: Neonatal separation of the distal humeral epiphysis (NSDHE) is a very rare injury. On one hand, anatomical reduction is usually required in pediatric elbow fractures due to limited remodeling potential at the distal humerus. But on the other hand, neonatal fractures often show favorable evolution without reduction, even in cases of severe displacement. NSDHE, often associated with traumatic deliveries, remains underreported, controversial, and its management lacks standardized protocols. Furthermore, its diagnosis can be difficult on X-rays as the distal humeral epiphysis is not ossified at birth. The study questions are: Can non-reduction orthopedic treatment of distal humeral epiphyseal separation yield good clinical and radiological outcomes? Are there risk factors for distal humeral epiphyseal separation? What relevant additional examinations should be performed?

Hypothesis: Orthopedic treatment without reduction may yield satisfactory clinical and radiological outcomes in NSDHE.

Patients and methods: This multicenter retrospective study included patients with NSDHE with at least two years of follow-up from four university hospitals. Data on delivery, diagnostic methods, and treatment types were collected. At the last follow-up, joint range of motion, clinical outcomes, and elbow radiographs were evaluated.

Results: Fifteen patients were included, with a mean age of 8,8 years at the last follow-up (ranging from 2 years to 29 years). All patients underwent an initial elbow radiograph, which was misinterpreted as an elbow dislocation in two cases. Two radiographs were initially deemed normal, necessitating further examinations (ultrasound, arthrography, Magnetic Resonance Imaging). Twelve patients were treated by immobilization without reduction, while two underwent surgical treatment with reduction under general anesthesia and percutaneous pinning. The non-operated patients had complete and symmetrical range of motion without complications, except for one case of resolving cubitus varus. One of the operated patients developed osteitis that required reoperation and also presented with resolving cubitus varus at 4 years old.

Discussion: Orthopedic treatment through immobilization without reduction appears to be a viable option for neonatal epiphyseal separation of the distal humeral, which are frequently mistaken for elbow dislocations on initial radiographs. Complementary examinations, such as ultrasound, can be useful to confirm the diagnosis. This series yields promising results, although the sample size remains limited.

Conclusion: Neonatal separation of the distal humeral epiphysis may represent an exception among displaced elbow fractures, as conservative management without reduction can lead to good clinical and radiological outcomes.

Level of evidence: IV; Retrospective case series.