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Many conditions affect the knee joint and cause symptoms.

Pain is the predominant symptom from most knee complaints. It is usually fairly well localised within the knee but can be more widespread and can sometimes also be felt in the shin area.

Ligament injuries, patellar instability and some cartilage tears can give rise to a feeling that the knee will give way (instability).

Cartilage tears are painful and may cause the knee to ‘lock’.

Swelling of the knee is a common symptom in any condition and can be quite impressive.

Limping is common with any painful condition of the knee.

This section concentrates on the following main conditions which affect the knee:

  • Cartilage Injuries
  • Anterior Knee Pain
  • Patellar Instability
  • Arthritis of the knee
  • Avascular Necrosis
  • Ligament Tears

Information on each of these conditions can be obtained by clicking on the appropriate tab at the top of this page.

The following basic knee anatomy provides a helpful reference for these pages.

Basic Knee Anatomy

Knee Anatomy (Click to Enlarge)

Knee Anatomy (Click to Enlarge)

The knee is a complex hinge joint that also allows some gliding and some rotation. Whilst the inside of the knee joint is continuous, it is divided into three compartments which are summarised in more detail in the table below.

1. Quadriceps Tendon
2. Patella
3. Patellar Tendon
4. Tibia
5. Fibula
6. Posterior Cruciate Ligament
7. Anterior Cruciate Ligament
8. Lateral Collateral Ligament
9. Lateral Meniscus
10. Lateral Femoral Condyle
11. Femur

The bones of the knee are the femur (thigh bone), tibia (shin bone) and patella (kneecap).

The surfaces of these bones within the knee are coated with cartilage (articular cartilage) which is very smooth.

Between the femur and tibia the medial meniscus and the lateral meniscus (a specialised form of cartilage) help to distribute load, absorb shock, stabilise the knee and aid in lubrication.

The knee joint is also lined by synovium, which produces a lubricating fluid.

The knee bones are connected by strong ligaments which stabilise the knee and allow it to function properly. There are two cruciate ligaments (anterior cruciate ligament and posterior cruciate ligament) and two collateral ligaments (medial collateral ligament and lateral collateral ligament).

Muscles around the knee provide movement. The muscles at the front of the thigh, the quadriceps, straighten the knee, and those at the back, the hamstrings, bend the knee.

All of these factors provide smooth, stable and pain free movement of the knee joint.

The three compartments of the knee joint are:

  • Medial Compartment (inner side of knee)
    • medial femoral condyle
    • medial tibial plateau
    • medial meniscus
  • Patellofemoral Compartment (front of knee)
    • patella (kneecap)
    • femoral trochlea (front of femur)
  • Lateral Compartment (outer side of knee)
    • lateral femoral condyle
    • lateral tibial plateau
    • lateral meniscus