Uncontrolled movements of the knee due to a lack of muscular control expose the knee to increased stresses and the knee and its cartilages (menisci) may suffer damage. One of the functions of the menisci is to control the large condyles of the femur as they move across the flat upper tibial surface and without this guidance there can be meniscal damage. The powerful condyles can move over the edges of the menisci, trapping them against the upper tibia and causing damage to their cartilaginous structure.
The types of damage pattern which can occur in the menisci vary and include the development of tears, splits and bites out of the edge. A "bucket handle tear" can develop if the condyle causes a circumferential split in the meniscus whilst the ends of the tear remain attached to the rest of the meniscus. An unplanned movement such as twisting and turning can damage a meniscus and dislodge a part of it into the joint as a loose body. This can move around inside the knee and jam between the surfaces of the joint, causing sharp pain and a giving way of the knee when it is weight bearing.
Ongoing degenerative changes in the menisci mean the condyles of the femur are less controlled and this heightens the stresses which are placed across the knee between the condyles. The articular cartilage surfaces can also degenerate in response to the increased stresses and this may lead to the development of osteoarthritis. If the meniscus was troublesome in the past the usual technique, before arthroscopy developed, was to remove the entire meniscus, which commonly lead to arthritic changes later in life. Knee problems lead to medial quadriceps wasting and a lot of treatments are prescribed to counteract this.
It is important to look at the accessory movements and the ranges of motion of the knee if strengthening is going to be effective for the inside quadriceps. The knee can be improved functionally by restoring the joint's accessory movements and the ability of the medial quadriceps to function will be greatly enhanced by restoring knee extension. Muscle strengthening exercises will not be effective without the joint's range being restored. The introduction of slim modern arthroscopes for knee surgery has meant easy visualisation of the knee interior and the ability to do the surgical minimum to achieve the desired goal.
Osteoarthritis is one of the commonest joint conditions in the world, affecting hundreds of millions of people and occurring almost universally to some degree in elderly people. A family history, meniscal surgery, joint trauma or ligament injury can all predispose the joint to later osteoarthritis. Damage to and stretching of either the medial or lateral ligaments can cause some sloppiness of the control of movement in the knee, causing increased forces to be generated across the joint and contribute towards articular surface breakdown. Shearing movements, causing a lateral stress as the joints are in contact, exert high forces on the surfaces.
The knee can start to develop a grating or clicking as it ages with small degrees of degeneration and is only painful if kept in one position for excessive periods. The joint capsule can become tighter if we do not perform the strong movements any longer which stress the joint to the ends of its ranges. This can increase joint compression which increases the stresses across the joint surfaces and make the joint more likely to be injured during stressful movements. As the process continues the cartilage wears down and the underlying bone, which normally has some elasticity, becomes denser and harder.
The symptoms of an osteoarthritic knee are typically pain, increased temperature, range of motion limitation, oedema, enlargement, joint crepitus and inability to do functional tasks. As the joint deteriorates it can go through cycles of pain and swelling, with walking become more restricted. Due to the difficulty of finding a comfortable resting position sleeping may become a challenge. Tenderness of the medial joint line means that pressure from another knee is not well tolerated in sleeping on the side, meaning a pillow is often required to allow comfortable resting.
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