Patella Luxation

What is It?

A bony deformity of the knee joint that causes the knee cap to dislocate. It can occur in any breed of dog but is very common in small breeds.

Various grades of the problem exist.

Grade 1 (subclinical), the kneecap slips out then goes straight back in.

Grade 2 (mild): kneecap slips out when the knee is bent then slips straight back in. 

Grades 1 and 2 may hold the affected leg up occasionally when walking or running but do not require surgery. Some dogs seem to skip occasionally as they walk or run.

Grade 3 (moderate) the kneecap is dislocated most of the time BUT can be easily replaced.

Grade 4 (severe) the kneecap is dislocated and cannot be replaced. 

Grades 3 and 4 require surgery to fix the problem as they are very lame. This can be particularly debilitating if both legs are affected.

How can we fix It?

Basically a knee reconstruction is required to correct the deformities that are responsible for the problem. A combination of the following may need to be undertaken:

  • Deepen the groove the knee cap runs in (trochleoplasty),
  • Realign the quadriceps muscles (tibial tuberosity transposition) or derotation suture
  • Tighten the outside ligaments and muscles (lateral retinaculum imbrication)
  • Release the inside ligaments and muscles (medial desmotomy, medial sartorius muscle release and quadriceps release).

Post Operative Care

A thick bandage is used for 5 days postoperatively and the sutures are removed at 10-14 days. A four week course of weekly Cartrophen injections are recommended starting at suture removal. These injections target the arthritic changes in the knee and may need to be repeated yearly.

Strict rest is necessary for 4-6 weeks to ensure the knee has healed sufficiently before a gradual reintroduction to on-lead exercise. The aim is to slowly improve the mobility and strength of the knee to allow normal limits of activity.

Some dogs may require pin removal 6-8 weeks after the operation if necessary.

If you have any further questions, feel free to contact us.