The following is designed to present an overview of arthroscopic surgery for the knee so that you might better understand what it is, what will happen during surgery, and what to expect before and after surgery.
First, I would like to define and describe some of the structures that constitute the knee joint. The knee joint is formed by the junction of the end of the thigh bone (femur) and the top of the shin bone (tibia). The end of the femur is shaped like two crescents (called the femoral condyles); the top of the tibia (called the tibial plateau) is shaped essentially flat, with two slight depressions to accommodate the condyles. These shapes allow the knee joint to bend and straighten, and are the weight-bearing surfaces of the joint.
There are two types of cartilage in the knee joint. The first type is located between the two bones of the joint, and these are called the medial and lateral menisci (meniscus, singular). The two of these cartilage structures sit on top of the tibial plateau; one on the inner side or medial side of your knee, and other on the outer side or lateral side of your knee. These are fairly thick, fibrous, C-shaped structures that cushion, protect and stabilize the knee, yet are often torn in injuries.
The other kind of cartilage lines the joint surfaces and acts like a cap to cover the ends of each bone. This cartilage is called articular cartilage. It is a smooth, slick, shiny white substance which, in its normal, healthy state, covers, protects and cushions the joint itself, as well as allowing the surfaces to glide against each other. You have probably seen this on the ends of animal bones, such as chicken joints, etc. This is the type of cartilage which is affected by the wearing-down process of arthritis.
I have told some of you that you may have chondromalacia of your patella (aka, the kneecap) or of the weight bearing surfaces of the joint. This condition, chondromalacia, is the degeneration of the articular cartilage which is part of the process of arthritis. The articular cartilage may become soft, irregular, rough, fissured or thinned out, or even a combination of all of these.
Sometimes a piece of articular cartilage becomes loose from an injury or other condition, and can “float” about within the joint; we call these pieces “loose bodies”. Sometimes they have a piece of bone still attached to them and can be seen on x-ray, and other times, if they do not have any bone, they cannot be seen on x-ray but can be seen with the arthroscope. Another term which you have probably heard in the conversations about the knee is ligaments. Ligaments are tough, rope-like structures which link the bones at the joints and help link the bones together.
Many patients who have knee arthroscopy have a torn meniscal cartilage. The purpose of the operation is to remove the torn part of the cartilage and leave undisturbed the normal meniscus that remains. Sometimes, it is necessary to remove almost all of the meniscus, but this is rare and unusual. More frequently, the tear is able to be repaired using sutures or even tiny “tacks”.
Regarding arthritis and chondromalacia, some special instruments can be used to smooth the loose and frayed pieces of cartilage which are seen with this condition. This results in improvement, but not cure, of this problem. Conditions such as a torn cartilage and chondromalacia are very often found in association with one another, and they will be treated together, if present. There are, of course, several other conditions which can be treated arthroscopically, and I will have discussed these other types of conditions and treatments with you.
Many patients who have a tear of one of the important knee ligaments, such as the anterior cruciate ligaments, also may, unfortunately, have a torn meniscus or injury to the articular cartilage. These individuals have a fairly high incidence of developing future joint irregularities, such as arthritis. If I think you have a torn anterior cruciate ligament, I will have discussed the implications of this rather serious problem with you and give you an informational handout regarding that injury.
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