Fractures of the Humeral Ulnar Condyle in Children - a Rare but Complicated Injury.

Background: Ulnar humeral condyle fractures are rare paediatric elbow fractures, classified as Salter-Harris IV paediatric elbow injuries. Due to constant radiological changes in the elbow with varying manifestation of ossification centres as well as late ossification of the trochlea, diagnosis of these injuries is challenging. To avoid long-term complications, the treating surgeon should be familiar with the rare injury picture, diagnostics and adequate therapeutic measures.

Material And Methods: The present retrospective study includes data on all paediatric cases from 2002 to 2019 with primary or secondary treatment at a paediatric traumatology centre for ulnar condyle fracture with a minimum follow-up of 12 months. Range of motion, joint stability under valgus and varus stress as well as axial ratios of the injured and uninjured side were evaluated in a clinical follow-up examination. The Mayo Elbow Performance Score was used to objectify functional results.

Results: 20 children, average age 8.6 years (4 - 13) and average follow-up time 25 months, were included. Radiological evaluation based on Jakob and Fowles classification revealed a type I fracture in three cases, a type II fracture in one case and a type III fracture in 16 cases. Three cases were treated nonoperatively with an upper arm cast. 17 children were treated with open reduction and internal fixation. Diagnosis of three fractures was delayed. No postoperative complications such as infections, nerve damage or nonunions. 15 children showed free elbow function. Three children showed slightly restricted elbow extension by less than 10° and two by 10°-20°. All children showed free pro/supination. 18 children showed a physiological and bilaterally identical arm axis compared to the uninjured side. Two children showed a slightly increased cubitus valgus with a 5 - 10° difference between sides. Radiologically, two children with delayed fracture treatment showed partial necrosis of the trochlea. The Mayo Elbow Score showed good (2) to excellent results in all children (18).

Conclusion: Very good clinical and functional results can be expected if the injury is diagnosed without delay followed by adequate therapy. Misdiagnosis of ulnar condyle fractures can be associated with the development of nonunions and functional restrictions as well as, after operative therapy, trochlear necrosis. Children up to the age of 6 in particular are at risk of misdiagnosis due to faulty assessment of the cartilaginous trochlea.