The knee is the largest joint in the body. The knee joint is made up of the femur, tibia and patella (knee cap). All these bones are lined with articular (surface) cartilage. This articular cartilage acts like a shock absorber and allows a smooth low friction surface for the knee to move on. Between the tibia and femur lie two floating cartilages called menisci. The medial (inner) meniscus and the Lateral (outer) meniscus rest on the tibial surface cartilage and are mobile. The menisci also act as shock absorbers and stabilisers. The knee is stabilised by ligaments that are both in and outside the joint. The medial and lateral collateral ligaments support the knee from excessive side-to-side movement. The anterior and posterior cruciate ligaments support the knee from buckling and giving way. The knee joint is surrounded by a capsule, lined by synovium that produces of synovial (lubrication) fluid to help with smooth motion. Thigh muscles are important secondary knee stabilisers.
Arthroscopy (keyhole procedure) on the knee allows to diagnose and treat conditions that affect the knee joint as a result of injury or wear and tear. Some of the conditions treated by knee arthroscopy are:
Meniscal cartilage tears. Following a twisting type of injury the medial (or lateral) meniscus can tear. This results either from a sporting injury or may occur from a simple twisting injury when getting out of a chair or standing from a squatting position. Our cartilages become a little brittle as we get older and therefore can tear a little easier.
Once a meniscal cartilage has torn it will not heal unless it is a very small tear which is near the capsule of the joint. Once the cartilage has torn it predisposes the knee to develop osteoarthritis (wear and tear) in 15 to 20 years. It is better to remove torn pieces from the knee if the knee is symptomatic. Torn cartilages in general continue to cause symptoms of discomfort, pain and swelling until the loose, ragged pieces are removed. Only the torn section is removed and the knee should recover and become symptom free. Occasionally, provided the knee is stable and the tear is a certain type of tear in a young patient (peripheral bucket handle tear), the meniscus may be suitable for repair. If repaired, one has to avoid sports for a minimum of three months.
Articular cartilage (surface) injury. If the surface cartilage is torn, this is most significant as a major shock-absorbing function is compromised. Large pieces of articular cartilage can float in the knee (sometimes with bone attached) and this causes locking of the joint and can cause further deterioration due to the loose body floating around the knee causing further wear and tear. Most surface cartilage wear will ultimately lead to osteoarthritis. Mechanical symptoms of pain and swelling due to cartilage peeling off, can be helped with arthroscopic surgery. The surgery smoothes the edges of the surface cartilage and removes loose bodies.
Anterior cruciate ligament injuries. Rupture of the Anterior (rarely, the posterior) Cruciate Ligament (ACL) is a common sporting injury. Once ruptured, the ACL does not heal and usually causes knee instability and the inability to return to normal sporting activities. An ACL reconstruction is required and a new ligament is fashioned to replace the ruptured ligament. This procedure is performed using the arthroscope.
Patella (knee cap) disorders. The arthroscope can be used to treat problems relating to kneecap disorders, particularly mal-tracking and significant surface cartilage tears. Patients may need to stay overnight if a lateral release has been performed as knee swelling is quite common. The majority of common knee-cap problems can be treated with physiotherapy and rehabilitation.
Inflammatory arthritis. Occasionally arthroscopy is used in inflammatory conditions (e.g. rheumatoid arthritis) to help reduce the amount of inflamed synovium (joint lining) that is producing excess joint fluid. This procedure is called a synovectomy. After the surgery a drain is inserted into the knee and patients generally require one or two nights in hospital.