Patellofemoral instability

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

Knee Instability – What Is It?

In some patients, the kneecap (patella) tends 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 lose confidence in their knee. Commonly this is called knee instability.

Knee instability is often due to an abnormality in how 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 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 what is happening with your patellofemoral joint.

Patella Instability Treatment

Patella instability is completely curable surgically with sports physiotherapy and surgical stabilisation.

As soon as possible, the kneecap needs to be gently relocated; this often occurs in A&E.

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 the joint), surgery is needed. The type of operation you need and the rehabilitation required varies from patient to patient, depending on whether the instability is due to a soft tissue laxity, a bony malalignment issue, or a combined abnormality.

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