Patellofemoral instability

Medically reviewed by Sam Rajaratnam FRCS (Tr. & Ortho).

Knee Instability – What is it?

knee brace

Knee Brace

In some patients, the kneecap (patella) has a tendency to disengage from its normal position and dislocate to one side. This can lead to a feeling of looseness and giving way of the knee, causing patients to easily lose confidence in their knee. Commonly this is called knee instability.

Knee instability is often due to an abnormality in the way the front of the knee joint is formed. For example it may be related to a shallow trochlear groove, a small and high placed patella, or there may be abnormalities in the soft tissues and ligaments around the knee. This is often called patellofemoral dysplasia.

Occasionally, patella instability can occur in a knee with normal anatomy, following a twisting or sporting injury. This is called a traumatic dislocation.

Patella Instability Diagnosis

A careful assessment of the patient’s clinical history and physical presentation, and a combination of special X-rays, CT scans and MRI scans will let your surgeon know exactly what is happening with your patellofemoral joint.

Patella Instability Treatment

Patella instability is completely curable surgically with a combination of sports physiotherapy and surgical stabilisation

As soon as possible the kneecap needs to be gently relocated; this often takes place in the A&E setting.

In some cases, conservative treatment which includes physiotherapy, hydrotherapy, taping and muscle building in the gym may treat the condition.

Often when the patella is recurrently unstable (i.e. the kneecap feels unstable and repeatedly comes out of joint), surgery is required to repair the medial patellofemoral ligament (MPFL) along with contracture releases and bony realignment procedures (called a tibial tubercle osteotomy).

The procedure that is required to correct recurrent instability of the patella depends on whether the instability is due to a soft tissue laxity, a bony malalignment issue, or a combined abnormality.

The necessary operation and rehabilitation thus varies from patient to patient. Depending on the exact cause of the instability, patients will have an individually assessed physiotherapy programme.

Mr. Rajaratnam has a particular interest in disorders of the patellofemoral joint, and has treated a number of patients with PFJ instability; most get back to active sports with confidence.