MRI for occult physeal fracture detection in children and adolescents.

BACKGROUND: Conventional radiography has limitations in the detection of physeal fractures before the closure of the physis occurs. Fracture detection may be improved by using magnetic resonance imaging (MRI).

PURPOSE: To evaluate the usefulness of MRI for the detection of occult fractures involving the physis when radiography results are negative.

MATERIAL AND METHODS: In this prospective study, 24 children (age range, 3-15 years; mean age, 10.7 years) received MRI if they met the following criteria: acute joint trauma, swelling and tenderness around the joint, limitations in bearing weight, an open physis, and negative radiography results for fractures. Fractures revealed by the MRI were classified according to the Salter-Harris classification system. Joint effusion, bone marrow edema, and periosteal alterations were graded on a three-point scale. The non-parametric Wilcoxon test and Fisher's exact test were used for the statistical evaluation.

RESULTS: From a total of 24 MR data-sets, 23 were evaluated (one patient was excluded due to poor MR image quality). Elbow injuries were present in 10 patients (43.5%), distal tibia injuries in 10 patients (43.5%), and distal femur injuries in three patients (13%). MRI results excluded physeal fractures in 15 (65.2%) of the 23 children. An occult physeal fracture was detected with MRI in eight (34.8%) patients; of these, five (21.7%) had fractures of the elbow, two (8.7%) had fractures of the distal tibia, and one (4.3%) had a fracture of the distal femur. All of the patients with fractures and 11 of the 15 patients without fractures demonstrated bone marrow edema.

CONCLUSION: The frequency of occult fracture, as detected by MRI, was 34.8%. Thus, MRI is a useful additional imaging method for the detection of occult fractures when radiography is negative.