The knee is the most commonly injured joint in the body

It is a modified hinge joint and relies upon strong ligaments and muscles for its stability

Most injuries to the knee involve either the patellofemoral joint, a ligament strain or cartilage (meniscus) tear

Most knee injuries can be improved significantly by modified activity, and specific muscle rehabilitation exercises

If a clear structural problem exists (e.g. unstable meniscal tear) then surgery is necessary

How do knee injuries occur?

Common causes of injury and the structures involved include:

Fall with impact on the front of the kneecap (patella). This injures the contact area behind the kneecap, called the patellofemoral joint.

Being tackled from the side, with the force causing opening up of the inner side of the knee, this strains the medial collateral ligament.

A twisting injury. This often injures the cartilage (meniscus) and a cartilage tear may result in knee locking.

A pivoting injury where the foot is planted. This injures the anterior cruciate ligament.

Symptoms

• Pain
• Locking
• Instability
• Swelling

Making a specific diagnosis:

Your doctor will ask you about how your knee injury occurred, and the particular symptoms mentioned above. Following this, an examination is undertaken.

Initial observation will reveal whether or not there is excess fluid on the joint, and if any scars (from previous injury or surgery) are present. Touching gently around the joint (palpitation) can help determine the site of maximum tenderness. Joint line tenderness is associated with a cartilage tear.

Testing the range of knee motion is then undertaken. Normal knee motion is from 0 to 140 degrees.

Finally, specific stresses through the knee can help assess any associated ligament tears. If there is increased excursion (laxity) on testing a particular ligament, then the ligament has either been significantly stretched or completely ruptured.

Once the above tests have been performed, the doctor should be able to make a working diagnosis - that is give a label to the problem that can be used to plan treatment.

What about rehabilitation?

All knee injuries can benefit from a planned programme of exercises. Initially, the aim is to reduce knee swelling and protect injured ligaments.

RICE is important in the first 48 hours after a knee injury.

Anti-inflammatory tablets may be prescribed for a few days, particularly if joint swelling is present.

If there are signs of a complete rupture of the medial ligament, a  brace may be helpful.

Once the first few days have passed, there is an emphasis on gradually restoring the full range of motion of the knee. Careful attention to maintaining function of the quadriceps muscles (at the front of the thigh) and the hamstring muscles (at the back of the thigh) is important.

Over the next couple of weeks, the aim is to have these muscles working in concert. Even though a ligament may be strained, good muscles can help in maintaining knee stability as the ligament heals. Swimming is useful at this stage.

Once the full range of knee motion has been restored, it is important to build power and endurance. Functional exercises (e.g. stair climbing) are generally of more use than expensive machines in achieving this.

As knee function improves, cycling then light jogging can commence. Once the person can jog painfree, then they can start speeding up and slowing down. If this causes no problem, they can try running around cones in a figure 8 pattern. The next step is to try cutting and turning movements. If these cause no problem, it is safe to return to team training.