Discoid meniscus is the most common anatomic meniscal variant [Abnormal shape from birth]. The incidence of this problem has been estimated to be around 5% in the general population. Normal meniscus is half moon [semi-lunar] in shape whereas the discoid meniscus as the name suggests is disc [circular] shaped. Because of its abnormal shape this type of meniscus has a tendency to get torn with normal knee activities also.
A patient with torn discoid meniscus will have pain while walking and especially on deep sitting [like which squatting in the restroom and on cross legged sitting]. Patients may also experience sounds from the knee and may occasionally have locked knee.
A torn discoid meniscus acts like a sandpaper in the knee and will rapidly wear out the normal smooth articular cartilage and will result in early onset arthritis.
The patient with a discoid meniscus may be asked to get an MRI scan of his\her knee to confirm the diagnosis. It is best treated with arthroscopy, during which the abnormal meniscus is brought to normal shape with arthroscopic instruments. The patient is free to resume all his usual activities in 1 week to 10 days after the surgery.