Medial Meniscus Injury
The meniscus is a small pad of fibrocartilagenous tissue present between the articulating bone ends inside the knee joint. There are two menisci in the knee joint, which should be distinguished from the articular cartilage that covers the bone ends.
The medial meniscus covers the inner half of the upper articulating surface of the tibia (shin bone), while the lateral meniscus covers the outer half. The medial meniscus is semi-lunar in shape; it is thin and pointed anteriorly with a wide posterior. The medial meniscus is less mobile compared to the lateral meniscus as it is more firmly held in place through ligaments.
Along with its lateral counterpart it provides structural stability to the joint and acts as a shock absorber. During the joint movement when femur and tibia make point contact, about two thirds of the load is absorbed by the menisci, which then disperse this load uniformly to the adjacent bone. This prevents load concentration at any one point, thus reducing the risk of damage to the articulating surfaces.
The medial meniscus is less mobile and more prone to injury than the lateral meniscus. Tearing may occur as a result of:
Trauma: an abnormal twisting of a flexed knee, posing abnormally great stresses on the meniscus. This type of injury is more common in young people, especially athletes. Trauma to the joint capsule (the outer protective covering) of the anterior cruciate ligament or to the medial ligament (fibrous bands connecting femur and tibia) may also lead to damage to the medial meniscus.
Degeneration: more common in the elderly.
- Pain starts gradually and involves the inner side of the knee.
- In case of trauma, pain may be immediate and bleeding may lead to sudden swelling. Otherwise, swelling develops over a day or two as a result of accumulation of inflammatory fluid.
- Pain intensifies on bending or rotating the knee.
- Cracking or popping sounds
- Knee hurts while rolling over in bed at night (Cooper’s sign)
- Tenderness around the front or back of the knee when pressure is applied
- Locking or catching of the joint during movement, the cause being the torn meniscus catching in between the two articulating bone ends, causing severe pain.
The history indicates the injury, as well as a positive McMurray’s test. In this test the knee is hyper-flexed and, placing one hand on the inner side of the knee with the other holding the foot, the lower leg is rotated internally while extending the knee. Pain or a popping sound on extension indicates a torn lateral meniscus. This test mostly helps to detect tearing in the posterior part of the lateral meniscus. Arthroscopy and MRI give a conclusive diagnosis.
Small tears detected early respond well to conservative treatment. The outer part of the meniscus has a good blood supply, so injury to this part usually heals well.
- The RICE protocol (Rest, Ice application, Compression and Elevation) to soothe the symptoms.
- NSAIDs to control pain and inflammation
- Knee support or crutches to take the load off during the healing period
- Massage and ultrasound therapy
- Steroids may be injected to control severe inflammation
- Muscle (quadriceps) strengthening exercises.
Glucosamine sulphate supplements are said to aid in meniscus healing.
Surgical treatment is through arthroscopy and involves:
Repairing the torn meniscus:
The torn part of the meniscus is debrided and smoothed. A longitudinal tear is repairable, while a horizontal or oblique tear generally isn’t.
Partial or Complete Menisectomy:
When the tear is large as a Bucket handle tear or when a part of the meniscus is detached, it needs to be removed surgically. However, the procedure is kept very conservative, preserving as much part of the meniscus as possible because otherwise the joint deteriorates more rapidly.
Rest and knee support such as a brace or crutches should be used during the healing period.
Resting period after the surgery varies according to the intensity of injury. Once pain and swelling subside rehabilitation should commence.
It aims to:
Improve the range of motion without causing pain
Strengthen the knee muscles to help decrease the load on the joint
Start with light stretching and bending of the knee. In the early stages, keep the motion passive by supporting the knee with a band or towel wrapped around the foot. Gradually increase the range of motion. Perform the flexion while standing, against gravity. And later on, placing your foot on a stool, bend forward flexing the knee to full range.
Work on your quadriceps and hamstrings. Strong leg muscles decrease the load on the joint, which helps to decrease the surface deterioration of the articulating surfaces that now lack the cushioning provided by the meniscus. It allows for better healing of a repaired meniscus or in its absence (partial or complete menisectomy) delays further deterioration of the joint.
Start with mild exercises and then progress to more difficult level.
Care must be taken to avoid over-exertion and stressing the wound, which may delay healing.