The knee is particularly vulnerable to injury and accidents due to its position in the leg, and injuries lead to pain, joint instability and loss of normal leg function. The initial part of the examination looks at the injury cause and the forces involved, how fast the knee effusion came up, the presence of joint instability on walking and whether the patient is unable to take normal body weight on the knee.

The amount of pain a patient suffers indicates the severity of the injury involved and the particular location of the pain can point to which anatomical structures have been injured. As the knee will be very difficult to walk on in the presence of a fracture these injuries are rarely missed in diagnosis. During the examination the physiotherapist will test the knee structures to look for the cause of the injury.

Objective Examination of the Knee

Knee effusion or joint swelling is an indication of the degree of inflammation present in the knee and the physio will check the amount of swelling manually. If the swelling is severe it can be drained using needle aspiration to relieve the pressure which can interfere with normal muscle recruitment and function. The physio records the movements of the knee on the plinth non weight bearing, assessing straightening and bending of the knee (extension and flexion) and the small degrees of rotation.

The patient is asked to move the knee and the physio judges how keen they are to move in the presence of pain, indicating where rehab needs to be started. Once the active range (what the patient does for themselves) is known the physiotherapist may try and push the joint a bit further to see if there is a problem or just guarding. Muscle testing of the quadriceps muscle for knee extension and the hamstring muscles for knee flexion inform the physio about the state of the muscles and how much strength the patient can exert without too much pain.

Stability is confirmed on a mechanically unstable joint by the ligaments and muscles. Physiotherapy testing of the collateral ligaments of the knee, the medial and lateral ligaments, is done by stressing the knee into knock-knee and bow-leg. These ligaments provide side-to-side stability to the knee. The anterior cruciate ligament and the posterior cruciate ligament are tested in the same way, giving front to back and rotatory stability to the joint. The joint structures are then palpated by the physio to confirm the diagnosis.

Physiotherapy treatment plan

An acutely painful knee is treated using the PRICE technique, starting with protection of the joint if necessary by using a brace to stabilise it. Crutches or sticks can be used to reduce weight bearing on the knee and allow a good walking pattern. Ice treatment, or cryotherapy, is a first line treatment for an acute knee, reducing pain and the swelling which permits increased movement and progression of treatment. A neoprene knee sleeve may be worn to squeeze the swelling and increase stability.

A reduction in swelling and pain allows the physiotherapist to give exercises to improve the knee's ranges of movement and strength. The largest and most powerful muscles are the quadriceps and the hamstrings. The quadriceps allows knee power for getting up from sitting, going up and down stairs and walking, keeping the knee stable. After the knee copes with exercise on the plinth the physio will move to exercises in weight-bearing and in more active activities.

Proprioception is the body's natural joint position sense, with the brain sensing the moment to moment position changes of the knee and co-coordinating the muscle actions needed keep the joint within safe bounds. Physio treatment is balance practice, starting with standing on one leg, then balancing and catching balls on a wobble board and finishing with running, changing direction suddenly, hopping and jumping. Once the swelling has settled and the strength and co-ordination ability restored the knee is ready to rejoin normal and sporting activities.