Patella (knee cap) subluxation/instability

The patella sits in a groove in the bottom of the thigh (femur) bone between to bony lumps (femoral condyles). When the patella temporarily and partially dislocates out of this groove patella subluxation has occurred.

This condition often occurs with knee straightening where the knee cap moves out of the groove laterally.

This condition can be related to a number of causes:

•    Poorly developed inner thigh muscles (stability muscles)
•    Over developed outer thigh muscles
•    A higher position of the knee cap (than normal)
•    Knocked knees
•    Underdeveloped lateral (outer) femoral condyle

Symptoms

You may feel the patella moving out of its grove. There may also be pain or swelling behind the patella. Pain may also be felt with bending and straightening of the knee.

Diagnosis and treatment

Your physiotherapist will be able to diagnose and treat this condition. In some cases an x-ray may be required to see whether there is underdevelopment of the outer femoral condyle.

Initial treatment would focus on reduction of any pain and swelling through the use of electrotherapeutic modalities, ice and rest from aggravating activities. Treatment would then move to focus on decreasing the activity of the outer knee/thigh muscles and strengthening of the inner thigh/knee muscles.

Decreasing activity of the outer thigh muscles may involve deep tissue massage, taping, electrotherapeutic modalities and stretching. Strengthening of the inner thigh muscles would involve a progressive program of strengthening exercises. Your therapist would also look at any other predisposing factors and treat these as appropriate, as well as assisting in your return to sport.