Patellofemoral Instability: Primary, Secondary, Causes, Symptoms, Treatment

 

Reviewed By: Pramod Kerkar, MD, FFARCSI

What is Patellofemoral Instability?

When the kneecap or the patella moves out of its normal alignment or position in the knee, it is known as patellofemoral instability. The patients feel as though their kneecap is 'slipping away.' They complain of feeling a loose movement in the knee. Patellofemoral instability is commonly seen in young and active individuals who are involved in sports and other physical activities. Injury to the cartilage may also occur. Patients experience pain and swelling in the anterior region of the knee. Patellofemoral instability is classified into two main groupings:

Patellofemoral Instability

Primary Patellofemoral Instability

This type of instability results from a number of different processes, such as lax or over-flexible ligaments around the knee, a high-riding patella (patella alta) and laterally placed tibial tuberosity.

Secondary Patellofemoral Instability

This results from a primary knee dislocation. The medial patellofemoral ligament keeps the patella stable and in position and prevents the patella from shifting laterally.This ligament may be severely damaged in a patellar dislocation resulting in patellofemoral instability.

Causes of Patellofemoral Instability

  • Faulty mechanisms in and around the knee.
  • High-riding patella (patella alta)
  • Lateral positioning of the tibial tuberosity.
  • Trauma or injury to the knee.
  • Primary knee dislocation.

Symptoms of Patellofemoral Instability

  • A feeling that the kneecap is loosened.
  • A feeling that the kneecap is 'slipping away.'
  • Sharp pain in the anterior region of the knee.
  • Inflammation in the injured region of the knee.

Treatment Options for Primary Patellofemoral Instability

Treatment may be non-surgical or surgical

Non-Surgical Treament for Primary Patellofemoral Instability

  • A knee extension brace should be used to immobilize the knee if the knee is swollen and painful.
  • Quadriceps strengthening, especially of the VMO (vastus medialis obliquus) muscle is recommended.
  • Patellar taping helps in correcting the patellar tracking.

Surgical Treatment for Primary Patellofemoral Instability

In conservative treatment fails then surgery should be done. It involves lateral retinacular release and other muscle fibres, VMO tendon advancement and tibial tuberosity transfer.

Treatment Options for Secondary Patellofemoral Instability

Non-Surgical Treatment for Secondary Patellofemoral Instability:

  • The same treatment is followed for secondary patellofemoral instability as for primary instability. A knee extension brace should be used to immobilize the knee if the knee is swollen and painful.
  • Quadriceps strengthening, especially of the VMO (vastus medialis obliquus) muscle is recommended.
  • Patellar taping helps in correcting the patellar tracking.

Surgical Treatment for Secondary Patellofemoral Instability:

In case of severe injury, repair of the medial patellofemoral ligament is done.

Pramod Kerkar

Written, Edited or Reviewed By:

, MD,FFARCSI

Pain Assist Inc.

Last Modified On: February 13, 2018

This article does not provide medical advice. See disclaimer

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