Meniscus is normally cresent moon shaped fibrocartilage tissue structure. We do have two menisci in each of our knees as medial and lateral. Medial meniscus and lateral meniscus are located between the distal femoral joint cartilage and proximal tibial joint cartilage. They are called as shock absorbers of knee. Not only they have a bumper role but also make contours of the tibial joint surface to perfectly fit with convex distal femur. That congruent fit of the joint provides an even distribution of the load. Whereas, Discoid meniscus is a disk-shaped meniscus which is wider than normal.
How common is the disorder?
Discoid lateral meniscus, 1.5-3%, discoid medial meniscus, however, occur in 0.1-0.3%.
What is the ethology?
It is a congenital problem related the intrauterine development of meniscus.It is present at birth. There are three types of discoid meniscus: 1-unstable meniscus, menisco-femoral ligament attachment to tibia is missing, 2-incomplete, meniscus is wider than normal, 3-complete, meniscus is disc shaped and covers the tibial joint completely.
What are the symptoms of the disease?
Discoid meniscus may not cause any complaints and can be diagnosed incidentally by MR. Asymptomatic cases do not require any treatment other than follow-up. Patients may complain about knee pain, popping sensation, even feeling the sound coming from the knee, knee swelling when it is complicated with injury. In discoid meniscus, incidence of meniscal tears is increased. In meniscus tear, swelling, knee pain and limitation of motion are commonly seen.
How is the diagnosis made?
Orthopedic surgeon may have a clue with the complaints and physical examination. Definitive diagnosis can be made with MR and diagnostic arthroscopy.
What is the treatment ?
Torn portion is removed with arthroscopic surgery in case of meniscus tear. In addition, the disc-shaped inner part of the discoid meniscus removed arthroscopically to convert the meniscus into a crescent-moon shape.