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Common Conditions - Patella Luxation - Dislocation of the Patella

Dislocation of the Patella

What is Patella Luxation?

The normal patella runs in an up and down direction within a groove on the thigh bone.  A luxating patella can slip in and out of its normal position in the patella groove.  Patella luxation is an extremely common condition in young small breed dogs such as poodles, Pomeranians, and Shih Tzus, and occurs occasionally in large breed dogs.

What causes Patella Luxation?

It is a congenital problem that is caused by abnormal alignment of the patella tendon, usually towards the medial side (towards the inside) of the leg. The problem can get worse as the dog grows due to the abnormal alignment.

What are the signs and symptoms?

Owners will typically notice an occasional skipping step or their dog will walk carrying a back leg.  Often the patella will spontaneously slip back into place and the dog will then walk normally, as if nothing has happened.

As the dog grows, the condition may get worse and they will limp or skip more often. 

When the patella slips in and out of its normal position the joint capsule is stretched and damaged.  This causes pain and inflammation and can lead to early arthritis in affected young dogs.

How do we treat Patella Luxation?

Treatment of a pet with a luxating patella is dependent upon the severity of the condition. There are 4 grades of patella luxation:

Grade 1: 

Luxation with manual pressure – usually not painful.  Grade 1 luxations usually do not require any specific treatment but do need to be monitored for worsening. Sometimes pain medication is required

Grade 2: 

Patella luxation with flexion and extension of the knee but returns to the groove on its own – occasional pain is present

Grade 3: 

Luxation with flexion and extension and returns to the groove with manual reduction – considerable pain and lameness (limping)  Grade 2 and 3 luxations usually benefit from surgical correction – this involves realignment of the patella tendon and deepening of the groove the patella sits in.

Grade 4: 

The patellas are permanently luxated – severe condition.  Grade 4 luxations usually require reconstructive surgery by a surgical specialist.

What happens If I don't do surgery?

Dogs with grade 2-4 luxations will experience pain occasionally to persistently depending upon the severity. Dogs with patella luxation are more prone to injuring their cruciate ligament as they get older.  Having a patella that slips in and out will cause arthritis - a painful and progressive problem.

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