Patellar instability: Expert insight on knee dislocation

In this informative guide, highly respected consultant orthopaedic surgeon Mr Hersh Deo gives an in-depth guide to patellar instability, a condition which affects the kneecap. The leading specialist discusses the causes and symptoms of patellar instability, and also reveals potential long term effects associated with the condition.

What is patellar instability?

Patellar instability is a condition that occurs when the kneecap (patella) slips out of its normal groove (trochlea) in the thighbone (femur). This is called a dislocation. This usually occurs as a result of a twisting injury and usually occurs in adolescents and young adults. It is more common in females. Most cases can be treated without surgery and with no long term issues. If the instability persists however, it can lead to pain and limitation of activities, particularly during sports that involve twisting.

What are the symptoms of patellar instability?

The primary symptom of patellar instability is a feeling of the kneecap slipping out of place. This sensation can be accompanied by pain, swelling, and locking or catching of the knee joint. In some cases, the kneecap may even dislocate completely, requiring medical attention to reposition it.

What causes patellar instability?

Several factors can contribute to patellar instability, including:

High patella (patella alta)

This when the kneecap is higher up the thighbone than normal. This can run in families.

Shallow trochlear groove (trochlear dysplasia)

The trochlear groove is the groove in the thighbone where the kneecap sits. A shallow groove can allow the kneecap to track abnormally, increasing the risk of instability and dislocation.

Ligament laxity

Loose ligaments around the knee joint can increase the range of motion and allow the kneecap to move outside of its normal groove.

Bony malalignment

Certain bony abnormalities, such as excessive valgus (knocked knees) can predispose individuals to patellar instability.

How is patellar instability diagnosed?

A thorough history and physical examination are essential for diagnosing patellar instability. Imaging studies, such as X-rays or MRI, may be ordered to assess the patellar tracking and identify any underlying bony abnormalities.

What are the treatment options for patellar instability?

Treatment for patellar instability depends on the severity of the condition and the individual's symptoms. Non-surgical treatment options often include:

Rest and activity modification

Avoiding activities that aggravate the knee joint can allow for healing and reduce the risk of further instability.

Strengthening exercises

Strengthening the quadriceps and hamstrings can improve muscle balance and support the knee joint.

Bracing

Wearing a brace for a few weeks can help stabilise the kneecap and prevent future dislocation.

Physical therapy

A physical therapist can provide personalised exercises and modalities to improve strength, flexibility, and proprioception.

In recurrent instability cases, if the above hasn’t worked, then surgical treatment may be recommended to address underlying anatomical abnormalities and to reconstruct the ligament that is torn. Surgical procedures may include:

Medial patello-femoral ligament reconstruction (MPFLR)

This anatomically reconstructs the ligament that is torn during patella dislocation. It is a day case procedure. You will be able to fully weight bear without a brace with a recovery time of about 6 weeks.

Lateral retinaculum release

Tightening of the outer tissue of the knee can add to patella instability and this procedure lengthens this tissue to re-balance the kneecap.

Realignment procedures

In cases of bony malalignment, surgical procedures may be performed to realign the patella or leg bones or to deepen the trochlear groove.

What are the long-term effects of patellar instability?

Patellar instability can increase the risk of developing osteoarthritis, a degenerative joint condition characterised by cartilage breakdown and pain. Early diagnosis and treatment of patellar instability can help minimise the risk of long-term complications.
 

If you are concerned about patellar instability and wish to schedule a consultation with Mr Deo, visit his Top Doctors profile today.