MR-IMAGING IN CONGENITAL LOWER-LIMB DEFORMITIES

Treatment for children with congenital deformities of the lower extrem ities may vary, depending on the state of the unossified skeletal stru ctures and surrounding soft tissues. The purpose of our study was to d emonstrate the spectrum of the osteochondral and extrasosseous abnorma lities as depicted with MR imaging. We retrospectively reviewed MR exa minations of 13 limbs of ten children (aged 1 month-9 years, mean 2.1 years) with longitudinal and transverse deformities of the lower extre mities. The lesions imaged were fibular hemimelia (n = 5), tibial hemi melia (n = 5), and congenital constriction bands (n = 3). Each examina tion was assessed for abnormalities in the osteocartilaginous and extr aosseous (articular or periarticular components such as ligaments, ten dons, and menisci; the muscles and the arteries) structures. Abnormali ties were seen in all patients. Osteocartilaginous abnormalities in th e patients with longitudinal deformities included abnormal distal femo ral epiphyses, abnormal proximal tibial physes, hypertrophied and disl ocated proximal fibular epiphyses, unsuspected fibular and tibial remn ants, and absence or coalition of the tarsal bones. No osteocartilagin ous abnormalities were seen in the patients with congenital constricti on bands. Articular abnormalities about the knee in patients with eith er form of hemimelia included absent cruciate ligaments and menisci, d islocated or absent cartilaginous patellae, absent patellar tendons, a nd abnormal collateral ligaments. All but one limb imaged had absent o r attenuated muscle groups. Of the nine MR arteriograms performed at t he level of the knee, eight were abnormal. The normal popliteal trifur cation was absent or in an abnormal location. We conclude that MR imag ing of children with congenital lower extremity deformities shows many osteochondral and extraosseous abnormalities that are not depicted by conventional radiography. This information can help to plan early sur gical intervention and prosthetic rehabilitation.