Image from www.orthoinfo.aaos.org
By Sue Reive
Many people suffer from knee injuries. One common injury is a tear of the meniscus, often referred to as torn cartilage. Indeed, meniscal injuries account for 15 per cent of all sports injuries.
The normal mechanism of injury involves torsion and compression of the knee; it occurs when a person is weight bearing on a slightly bent knee and then turns, twisting the knee. This movement occurs in numerous sports including racket sports, football, ultimate and hockey. Moreover, the meniscus can be injured if one slips and falls while walking. Minor tears are usually successfully treated with physiotherapy while major tears often require arthroscopic surgery followed by extensive physiotherapy.
The meniscus is a soft tissue that sits between the bones of the knee (the femur and tibia). There are two crescent-shaped menisci in the knee: medial (inside of knee) and lateral (outside of knee). The menisci attach to the tibia and femur by ligaments and to the capsule of the knee joint, the soft tissue that holds the bones of the knee joint together.
The meniscus acts as a cushion which absorbs shock and transfers the load. Moreover, it improves joint stability and aids in lubrication. The outer third of the meniscus has a blood and nerve supply while the inner two thirds do not. This is important because if there is a tear where there is no blood supply, the meniscus cannot heal.
Meniscal tears can be classified as acute traumatic or chronic degenerative. They can also be classified by the size of the tear: partial or full thickness. Further, they are categorized by the shape of the tear: around the periphery of the meniscus (rim lesion) or in the centre, causing a flap in the meniscus (a bucket-handle tear), which can cause the knee to lock.
Individuals older than 50 are more likely to have some degenerative changes in the meniscus and possibly some osteoarthritis in their knee as well; in these people, a normal stress on the knee such as prolonged squatting or climbing too many stairs or a slip on the ice can cause the meniscus to tear.
Symptoms of meniscal tears include swelling, limited mobility, pain with walking, squatting and twisting, and a feeling of locking and clicking. Treatment depends on the size and type of tear. Assessment includes specific stress testing and measuring range-of-knee-motion and strength. As well, imaging such as an ultrasound or MRI is often done to visualize the menisci and see the extent of injury. An X-ray is beneficial to see if there is any osteoarthritis in the knee. Minor tears in the outer third of the meniscus can heal with physiotherapy. Larger tears will often require surgery to remove the torn flap of the meniscus. In some cases, the meniscus can be sutured.
Physiotherapy treatment includes exercises to improve mobility and strength in the knee and hip, balance and agility drills, and a gradual return to sport. Modalities can aid in the healing process by enhancing blood flow to the knee. Manual therapy also helps regain mobility.
Unfortunately, surgical meniscectomy often leads to increased wear and tear on the joint. Studies have shown that when the meniscus is removed, the peak contact pressure between the tibia and femur increases by two or three times. Moreover, a review of many studies found that on average 53.5 per cent of patients developed osteoarthritis in the surgical knee five years post-operatively, hence the reason to try to preserve as much of the meniscus as possible.
When patients still suffer pain and disability after a meniscectomy (total or partial), a meniscal allograft transplantation is a possible option. This involves taking a meniscus from a young cadaver and transplanting it into the patient. Patients must meet specific criteria, including being under 50 to 55 years and suffering a lot of pain and disability post meniscectomy.
Susan Reive is the owner of Kilborn Physiotherapy Clinic.