Luxating patella surgery (dogs and cats) advice please

Re: Luxating patella surgery (dogs and cats) advice please

Tim Browning — Mon, 05 Mar 2012 09:08:18 GMT

It seems to me the underlying cause is the relative inwards rotation of the tibia on femur especially in breeds like SBT with bent legs and a 'natural' force for luxation as the shortest line between two points. SBT also prone to traumatising themselves.

This requires TCT and this is successful in the short term but maintains the underlying rotational deformity which leads to DJD in time (which usually happens anyway in the breed).

In much smaller breeds/cats the ligaments are much laxer, joint has a lot of lateral movement absent in chunkier joints e.g. CKC and the whole tibia can be rotated outwards by a simple suture from femoro/fabella lig to tib crest and this stabilises the whole joint in a more anatomical position (with other stabilisation techniques, capsular release medial/overlap laterally /groove deepening if necessary).

TCT in cats and small breeds is a bit fiddly

Re: Luxating patella surgery (dogs and cats) advice please

Fiona French — Sun, 04 Mar 2012 22:59:05 GMT

As I understand it, the shallow trochlea groove and the lax lateral joint capsule are secondary changes, so you can adjust these to give temporary correction, but the primary problem is the malallignment of the quadriceps apparatus, so you really need to preform a tibial tuberosity transposition to permanently correct the problem. Top tip for this is to try to leave the periosteum intact at the distal end of your cut so you can just rotate it from there. Use rongeurs to create a flatish surface for it to sit on, and insert a pin +/- tension wire. If there is grade 4 patella luxation (permanently luxated and cannot manually replace) or if the femurs seem very bowed, osteotomies are likely to be required, which will require referral.

A wedge sulcoplasty is supposed to be better than a V, but I tend to still use a V as I find it easier, and they all seem to do well with this. I use a number 11 scalpel blade to draw onto the cartilage where I plan to cut, the cuts should be just inside the highest points of the groove. Once the V has been removed, cut away a thin sliver form the lateral side (if medial patella luxation) and replace your piece of bone. If it rocks from side to side either use your saw to deepen the middle part of your V, or carefully trim the point of your excised piece of bone with rongeurs.

I have found no significant differences in performing this op between cats and dogs. I do not advise surgery unless the patella luxation is associated with a clinical problem. There are lots of toy breed dogs who seem to be in no discomfort at all with their patellae popping in and out, and never seem lame, and they can be made worse with surgery.

Re: Luxating patella surgery (dogs and cats) advice please

Rob Loxley — Sun, 04 Mar 2012 22:34:46 GMT

I'm thinking I'd want to know if it's an immature or mature animal, medial or lateral, uni/bi-lateral, what the grade of luxation is, whether is developmental or traumatic luxation, what the clinical picture is re gait/lameness, whether there are any secondary skeletal growth abnormalities etc., to decide if surgery is needed and if so what surgery (soft tissue manipulations, sulcoplasty, crest transposition, corrective osteotomy etc.).

I get the impression the mood is to operate less on the low grade, less significant luxations in mature animals, but to be more concerned about early intervention in immature, particularly severely affected, animals to try and stop them developing nasty skeletal growth abnormalities?

Re: Luxating patella surgery (dogs and cats) advice please

Nicola Lawlor — Sun, 04 Mar 2012 22:08:55 GMT

Fab - thank you

Re: Luxating patella surgery (dogs and cats) advice please

Mark Hedberg — Sun, 04 Mar 2012 21:19:31 GMT

[quote user="Nicola Lawlor"]

Will the cartilage just sit in the recess without being otherwise fixed in place once the rest of the joint is closed back up?

[/quote]

yes, for 2 reasons: 1, the patella and ligament keeps pressure on; 2, the contact surface beneath your recessed wedge is very rough and so static friction is very high and won't move. Oh, and the rest is important too - no running/jumping for a while, same as many other ortho ops.

Re: Luxating patella surgery (dogs and cats) advice please

Robin Grimmer — Sun, 04 Mar 2012 19:27:50 GMT

[quote user="Nicola Lawlor"]

Will the cartilage just sit in the recess without being otherwise fixed in place once the rest of the joint is closed back up?

[/quote]

Yes. The patella will keep it in place. I've done all methods over the years but I haven't done one for ages. I think surgery is generally less recommended now than it used to be?

Re: Luxating patella surgery (dogs and cats) advice please

Nicola Lawlor — Sun, 04 Mar 2012 19:24:32 GMT

Will the cartilage just sit in the recess without being otherwise fixed in place once the rest of the joint is closed back up?

Re: Luxating patella surgery (dogs and cats) advice please

Mark Hedberg — Sun, 04 Mar 2012 18:35:32 GMT

Deepening the groove isn't particularly difficult...cut a v under the groove, keep the chip of cartilage wet, cut a deeper v under that raw surface, remove that wedge, replace the original articular surface, which is now recessed. Strict rest for a few weeks, then gentle physio. (obviously i defer to more experienced specialists, but i don't feel comfortable removing a kneecap. Even if my mother seems to be doing well - i didn't do that op! (1970s) )

Re: Luxating patella surgery (dogs and cats) advice please

Michael Woodhouse — Sun, 04 Mar 2012 14:55:45 GMT

[quote user="labrador four"]remove the patella,[/quote]

Am I reading this wrong? The NHS spends millions fitting people with artificial patellae................

Re: Luxating patella surgery (dogs and cats) advice please

Don Rutherford — Sun, 04 Mar 2012 14:40:52 GMT

Sever the ligaments immediately adjacent to the patella, remove the patella, close the capsule and skin. No dressing needed. A ten minute op.

I have done twelve plus over the years and all recovered normal function, usually within a week - the longest was three weeks. This is obviously when luxating patella was the only problem.

Re: Luxating patella surgery (dogs and cats) advice please

Julian Earl — Sun, 04 Mar 2012 13:34:35 GMT

We don't operate on many of these anymore. I believe that 99% don't cause significant problems, or if they do, the surgery is more painful than the diseasae.

Having said that, the key to me was to sever the medial ligament rather than just shortening the lateral one. Deepening the groove always seemed very very traumatic and painful, far less than the transposition of the crest.