DISCOID MENISCUS IN CHILDREN - MAGNETIC-RESONANCE-IMAGING CHARACTERISTICS

Objective: To describe the magnetic resonance imaging (MRI) appearance and associated abnormalities of discoid menisci in children. Patients and methods: The MRI findings for a total of 30 knees (in 20 children ranging in age from 4.5 to 16 [mean 9] years) in which discoid menisc us had been diagnosed were reviewed and correlated with clinical sympt oms and arthroscopy findings. Results: The symptoms, bilateral in 5 pa tients and unilateral in 15, included pain in 15 knees, snapping or cl unking in 8, reduced mobility in 8, locking in 2 and ''giving-way'' in 2; there were flexion contractures in 2 patients. Five patients had u nilateral symptoms but bilateral discoid menisci. The transverse diame ter of the meniscus ranged from 18 to 37 mm and the depth from 14 to 3 6 mm. The lateral meniscal height was significantly greater than the m edial meniscal height (p = 0.0001). On T-1-weighted and T-2-weighted i mages the meniscal signal was increased heterogeneously in 11 knees, i n a central, horizontal, linear fashion in 9, diffusely in 6 and in a partly linear, partly diffuse fashion in 3. Thirteen joint effusions, 10 lateral meniscal tears and 4 meniscal cysts were identified. Eight arthroscopy procedures were performed in six of the children (for seve n knees). Discoid meniscus was confirmed in six knees (with one initia l false-negative result), tears were confirmed in four, and an additio nal tear was identified in one; in addition, one meniscus was characte rized as Wrisberg type. Conclusions: Discoid meniscus commonly occurs bilaterally. High intrameniscal signal is found, especially in symptom atic patients. The size criteria for diagnosing this condition in chil dren are similar to those for adults.