KNEE PROBLEMS

Anatomy

How the knee joint works

The joint is stabilised by:

Ligaments

These are supportive tissues preventing excessive excursions of the tibia (shinbone) on the femur (thighbone). The anterior cruciate ligament is one of these ligaments with a definite role in regulating the knee joint biomechanics. Rupture of the anterior cruciate ligament produces laxity of the knee joint increasing the movement between the femur and the tibia. It also allows rotatory instability.

This rotatory instability imparts the feeling of insecurity and giving way. If the 'giving way' is severe enough to occur in the activities of daily living then a reconstruction of the anterior cruciate ligament is advisable. Similarly, reconstruction is often indicated if major sports are to be undertaken in the future. Such a reconstruction will then render the knee joint stable and will also decrease the tendency for cartliage tear and osteoarthritis to develop later in life.

Muscles

The thigh muscles provide the power to mobilise the knee joint and are secondary stabilisers to the joint. Whilst reconstructive surgery re-establishes the torn ligament correcting a mechanical problem, it is the muscles which power the joint into good function. It is absolutely essential to keep the thigh muscles in excellent condition if good function is to be expected from an injured knee joint. It is for this reason that physiotherapy to rehabilitate the injured knee joint is vital both before and after a reconstructive procedure. Pre-operative physiotherapy familiarises the patient with the type as well as the intensity of the necessary exercises, helping the patient to build up the thigh muscles, reduce the swelling and improve the range of motion.

The knee is cushioned by;

Meniscus

The menisci (plural of meniscus) are horizontal horse shoe shaped wedges of tissue that exist both on the inside and outside aspects of the knee acting as shock absorbers between the long bones making up the knee. They are made of smooth white glistening fibrous material, and have a vital function in reducing dissipating shock forces acting on the knee during day to day activity. Each knee has 2 menisci, one to support each of the rounded ends of the femur (thigh bone). They are wedge shaped and curved, with the wider part of the wedge forming the outer rim and the inner rim being the sharp surface. The majority of the meniscus does not have a blood supply and it is for this reason that healing of these tissues once damaged is virtually impossible.

Consequently, people who have damaged their cartilages often ultimately require surgery to excise the torn fragments.