Sam gets "knee capped" again

Sam is a 5 year old Kelpie cross who was presented at our clinic with a history of intermittent left hind lameness. Poor Sam had already had surgery on his right knee, and now it appeared that his left knee was affected too.

When a lameness comes and goes like this, but never seems to resolve, we are often suspicious of patella (or "knee cap") problems. In dogs, as in humans, the knee cap supports the thick tendon that runs from the large quadriceps muscle groups in the upper leg to the front of the tibia just below the knee. When the quadriceps contracts the tendon pulls on the tibia causing the lower half of the leg to kick forward (knee extension).

The patella is supposed to sit snuggly in a groove at the end of the femur. Sometimes the patella slips out of this groove, and will sit on the inside of the knee. This might happen if the groove is too shallow, or if the alignment of the knee is such that the patella is dragged sideways when the quadriceps contract.

As you can imagine, when the patella is out of place (or luxated) the knee becomes quite sore and has reduced function. This is when the dog exhibits lameness. When the patella flicks back into place, the leg can behave normally again.

In Sam's case (and many other small to medium dogs), his patella was out of place more often than not. He was in pain for most of the day.

Patella luxation can be resolved by surgical correction which involves deepening the groove and realigning the tendon. Sam has had this procedure performed here at Blackburn Veterinary Centre, and now can enjoy life with a happy and healthy knee!

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