What is patellofemoral instability?

Patellofemoral instability is when the kneecap (patella) does not stay reliably within its groove at the front of the thigh bone, and slips partly (subluxation) or fully (dislocation) to the side. It is common in adolescents, particularly during growth and sporting activity, and can become recurrent once it has happened.

Signs and symptoms

• A sensation that the knee “gives way”

• The kneecap visibly slipping to the side

• Pain at the front of the knee

• Swelling after activity

• A frank dislocation, which sometimes needs to be put back into place

How is it diagnosed?

A clinical examination assesses how the kneecap tracks and how much it can be displaced, as well as the underlying alignment of the leg. X-rays and an MRI scan are often used to look at the shape of the bones, the position of the kneecap, and any damage to the cartilage or the stabilising ligament (the MPFL).

Treatment options

First-line treatment is usually physiotherapy to strengthen the muscles that stabilise the kneecap and improve its tracking. Where instability is recurrent, surgery may be recommended — this can include reconstructing the stabilising ligament (MPFL reconstruction) and, in some cases, addressing the bony alignment. The right approach depends on the individual anatomy of the knee.

Outlook

With the right combination of rehabilitation and, where needed, surgery, most young people return to full activity and sport.

When to seek advice

After a first dislocation, or if your child’s kneecap repeatedly feels unstable or gives way.

This information is for general guidance only and is not a substitute for a consultation with Mr Wadia. If you are worried about your child, please seek medical advice.