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March 5

Patellar Luxation surgery – a new technique.

At Abbotts Way Veterinary Clinic we have started using the Ridgestop method which will replace the older trochleoplasty surgery.

The patella normally tracks up and down the trochlear groove at the end of your thighbone just above the knee joint. In dogs that have had patellar luxation, the trochlear groove tends to flatten out and the ridges of the trochlear groove become worn down.
Using the trochleoplasty method the hyaline cartilage was removed and then a little bit of bone underneath was removed and the hyaline cartilage replaced. Whilst this was the best that we could do I always felt that when the cartilage healed it would never be quite as good as it used to be.
The “ridgestop” method uses a surgical implant attached by 2 or 3 screws to either the lateral or the aim of the surgery is to make sure that the patella slides up and down within its groove, without slipping to one side or the other, causing discomfort and lameness.

This surgery works by applying a special implant (a prostheticridge called RidgeStop™) using screws onto the side of the groove where the knee cap was dislocating, thereby creating a barrier which prevents this from occurring. The surgery involves opening the knee joint space, examining the joint, and fixing the implant (made of an ultra-high molecular weight polyethylene) to the bone using 2 or 3 screws.
Unlike other procedures for this condition where the joint surface had to be cut, this is a much less traumatic procedure, as well as being more effective. As no bones have been cut, there is no risk of fracture and therefore no need to restrict exercise after surgery – it is actually encouraged. However, it is important to take into account that there is still some pain and discomfort after surgery, so a non-steroidal anti-inflammatory pain killer should be used for a period of 4-6 weeks after surgery.

You may have been given some antibiotic treatment as well for a few days post operatively. It is recommended to exercise on a lead only, as well as prevent swimming, to reduce risk of contamination or injury to the surgical wound until it has healed, which usually takes 10-14 days.

RidgeStop™ prosthetic trochlear ridge
After-care information for clients

What to expect after surgery:-
Normally you should see your pet start using their leg 3 to 4 days after surgery, and slowly improve over the following 3 to 4 weeks. There is some individual variation on how quickly your animal will return to full function, and is suspected to be due to having to adjust to the new biomechanical state of the knee joint, and to the implant itself.

Occasionally some swelling is seen post operatively around the knee joint due to fluid accumulation (seroma), however this usually resolves without incident after a few weeks. Additional surgical procedures in conjunction with the RidgeStop™ implant depending on the severity of the condition, additional surgical measures may have had to be performed. This could be involving sawing of the tibial and/or femoral bones, which help re-align the knee cap. In cases where the surgery involves the sawing of bones, all the forces acting on these bones are countered by the pins and wires or even plates and screws, and whilst these are of adequate strength, they may still fail if excessive force is applied, for example by jumping, running and sudden twisting.

It is therefore imperative that if in addition to the RidgeStop™ implant bones had to be cut and repositioned in your pet, exercise is restricted to controlled lead walks only, no stairs and not letting free in the garden until the bone heals. This can take 2 to 3 months depending on the age of your pet, and is confirmed by post-operative x-rays at the appropriate times as advised by your vet.

For more information on the “Ridgestop” implant surgery please contact me by email
at:-david@abbottswayvet.co.nz

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