Slipped capital femoral epiphysis: a physeal lesion diagnosed by MRI, with radiographic and CT correlation.

OBJECTIVE: To define and compare early lesions associated with slipped capital femoral epiphysis (SCFE) on magnetic resonance imaging (MRI), computed tomography (CT) and radiography.

DESIGN AND PATIENTS: Thirteen patients with 15 symptomatic hips due to SCFE underwent radiography and MRI; CT was performed in 12 patients. SCFE was graded on radiographs, head/neck angles and qualitative changes were evaluated on CT, and morphologic/signal abnormalities were determined on MRI.

RESULTS: Physeal widening, apparent on T1-weighted MRI, was evident in every case of SCFE, including one presumed "pre-slip." T2-weighted images demonstrated synovitis and marrow edema but obscured physeal abnormalities. CT head/neck angles ranged from 4-57 degrees for symptomatic to 0-14 degrees for asymptomatic hips. Physeal and metaphyseal changes were variably identified on both radiographs and CT in all cases of SCFE, but not in the pre-slip.

CONCLUSION: MRI clearly delineates physeal changes of both pre-slip and SCFE, and demonstrates very early changes at a time when radiographs and CT may appear normal.