Jul 4, 2013 / 5:00 am
Injuries to the meniscus (cartilage) of the knee are common and typically occur while participating in sports, but can also occur in activities of daily living, or in older individuals due to degeneration. Approximately 1/3 of all meniscal tears are associated with an ACL (anterior cruciate ligament) tear as the ACL attaches adjacent to the lateral meniscus.
The meniscus consists of fibrocartilage that resembles two C-shaped structures that attach onto the tibial plateau, which is where the lower leg bone (tibia) meets the femur (thigh bone) at the knee joint. There are two menisci - the medial (inner) one is C-shaped, while the lateral (outer) one is more semi-circular in shape. At birth the entire meniscus has a blood supply. By the age of 9 months the blood supply starts to decrease and by the age of 10 years only 10-25% of the lateral meniscus is vascular (has a blood supply), while 10-30% of the medial meniscus is vascular.
Functions of the menisci include sharing the load or weight bearing of the knee, reducing knee joint stresses, shock absorption, and stabilization of the knee. Method of injury typically includes a history of twisting while weight bearing, or hyperflexion of the knee. Tears may also occur in older individuals due to degeneration of the meniscus itself. The patient normally presents with joint line tenderness, moderate swelling, pain, and limited extension. The patient may also experience "locking" of the knee in flexion (bent position), where the tear in the meniscus flaps over on itself preventing the leg from straightening fully.
There are numerous tests that can be performed in a physical examination to assess for meniscal pathology. Range of motion, strength, and special tests that can predict meniscal tears are often performed. Despite these tests, a MRI is one of the most useful diagnostic tests that can be performed to indicate meniscal tears with 100% certainty. Meniscal tears can be classified depending on the type and location of the tear. These classifications are as follows: oblique (flap or parrot-beak), vertical longitudinal (bucket-handle), transverse, horizontal cleavage, or complex. Several studies have indicated that 81% of tears are oblique or bucket-handle in nature. In addition, as patients age, the incidence of complex tears increases. An orthopedic surgeon can determine if a tear will require surgery. Indications for meniscal surgery may include symptoms that limit activities of daily living, work, or sports or where conservative treatment has not improved symptoms.
Conservative treatment such as physiotherapy can help reduce swelling, improve range of motion, reduce pain and improve strength. Stay tuned for my next column on specific exercises and physiotherapy modalities for meniscal tears.
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