Trochlear deformity occurring after distal humeral fractures: magnetic resonance imaging and its natural progression.

Eighteen children (mean age 50.7 months) with trochlear deformities occurring after and related to distal humeral fractures (12 Salter-Harris type 2, 5 supracondylar, 1 Salter-Harris type 4) were evaluated with serial radiographs. The carrying angle and range of motion were measured throughout the follow-up period (up to 13 years after trauma) after definitive treatment. Bony defects on the medial (17 patients) and central (1 patient) regions of the trochlea were observed at a mean of 3.4 months after the trauma. They also persisted up to 4 to 7 years (latest follow-up in an intermediate follow-up group) and eventually reossified by skeletal maturity (in a long-term follow-up group). Magnetic resonance imaging was performed on eight patients after a mean of 1.9 years from injury. Low signal intensity on T2 indicative of cartilage necrosis and an intact articular surface were found. Cubitus varus deformity, which developed in almost all patients, was observed to be nonprogressive after 3 to 4 years but persisted until maturity. Limitation of motion and late neuropathy were not seen.