Magnetic resonance imaging of knee injuries in children

The purpose of this study was to evaluate the significance of meniscal appearances and determine the frequency of abnormalities seen on magnetic resonance (MR) imaging in children with knee injuries. We reviewed 78 consecutive MR imaging studies of 74 children aged 5-16 years with unfused epiphyses. Menisci were evaluated using conventional grading techniques. We used chi2 to compare the frequencies of medial and lateral meniscus and anterior cruciate ligament (ACL) tears with each other and with published data for children. Similarly, we compared the proportions of tears of these structures with published data. Arthroscopy results from 26 children were used to calculate sensitivity and specificity of MR imaging for meniscal tears, which were 100% (8/8) and 89% (16/18), respectively. The majority of studies (82%) had grade I or II signal intensity in one or both menisci. Arthroscopy results available in 33% of this group revealed normal menisci. Tears of the medial and lateral menisci were significantly more common than of the ACL. Injuries of the ACL were seen significantly less frequently than previously reported. Grade I or II meniscal signal intensity in children with knee injuries is consistent with a normal meniscus. Tears of the menisci are more common than ACL tears. MR imaging in this context appears reliable.