The clinical manifestations of discoid meniscus in children are usually different from those in adults. We attempted to find the relationship between the clinical symptoms and shape of discoid meniscus in children.

Thirty-one children, ranging from 5 to 17 years of age, with 32 discoid lateral menisci that underwent arthroscopic examination and MRI study were included. The clinical symtoms were reviewed by medical records. MR images were reviewed for the presence of meniscal tear and Wrisberg ligament, etc. Also, the absolute and relative thickness in anterior, posterior, mid-medial and mid-lateral portions were measured. The shape of the menisci were classified by the modified Hall's scheme.

: The two most frequent complaints were pain (21 cases, 66.6%) and extension block (23 cases, 72.9%) . In 18 cases without surface tear, the most frequent clinical findings were extension block (14 cases, 78.8%) . The shape of the menisci correlated with the extension block. The mean thickness of the anterior portion of discoid lateral meniscus (7.12mm) in extension block (+) group was significantly larger than that (4.01mm) of the extension block (-) group (P=0.019) . The extension block was significantly higher in anterior asymmetric type (3/3) and slab type (19/21) than posterior asymmetric type (2/8) (P=0.003) .

The main clinical symptoms in children with discoid meniscus were pain and extension block. The extension block seemed to strongly correlate with the shape of the meniscus. The thickness of the anterior portion of the discoid lateral meniscus is also considered a related mechanical factor that determines knee extension.