Luxating patella in young dog

RE: Luxating patella in young dog

Gillian Mostyn — Sat, 15 Aug 2020 12:00:41 GMT

[quote userid="8958" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224928#224928"]He pointed to the underside of the patella and it was inflamed.[/quote]

I assume the dog was already showing pain (lameness) in that leg? I have no doubt that where there is already pain, the surgery is indicated. It is where there is laxity found on exam, but without symptoms, that I wasn't sure.

RE: Luxating patella in young dog

Neil Wheadon — Sat, 15 Aug 2020 11:28:12 GMT

I locummed with an orthopaedic surgeon last year and he was doing a transposition. He pointed to the underside of the patella and it was inflamed. I was very much under the impression that if left this causes chronic pain, therefore they should be considered. The issue with dogs of course is that they are not great at showing pain, so are these chronic luxating cases living with chronic pain and does the inflammation get worse?

Neil

RE: Luxating patella in young dog

Gillian Mostyn — Sat, 08 Aug 2020 09:46:34 GMT

Malcolm Ness

Thank you!

[quote userid="3607" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224797#224797"]That was always (rightly in my view) considered a primary care practice procedure.[/quote]

Completely agree. It was a surgery I did moderately regularly in practice at first (maybe half a dozen every year) but it decreased with time (as colleagues in practice usually offer referral to anything insured) and I rarely see any ortho work at all in first opinion practices these days. As I'm a locum I am cautious about doing any surgery where follow-up in practice, such as implant removal etc., isn't possible. I don't think it is fair to the client.

I appreciate your opinion on the need for surgery or not. If I found the laxity as an incidental finding then I certainly left alone, but puzzled over the ones that came in for 'skipping'. They genuinely didn't seem painful on manipulation so I always assumed mechanical lameness, bit it is hard to know. And I always suspected that even after surgery they may continue to do the same so as you say assessment is tricky

Good to know that any resulting OA tends to be mild.

Have a good weekend.

RE: Luxating patella in young dog

Malcolm Ness — Sat, 08 Aug 2020 08:46:08 GMT

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224783#224783"] but would like to know which ones should be redirected to an ortho! [/quote]

The overwhelming majority of patella surgery is based around tibial crest translocation. That was always (rightly in my view) considered a primary care practice procedure. Sadly, the average surgical skill level in primary care practice has diminished and things are made worse by some referral practitioners and university teachers who suggest that almost everything warrants referral.

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224783#224783"]I always assumed (possibly incorrectly) that a patella that luxates frequently is likely to result in OA in the future[/quote]

That is frequently used to justify early and often aggressive surgery. Patella luxation does drive OA but the OA associated with even clinically significant patella luxation is typically rather low-grade. We do see localised chondral erosion in some cases but that is a mechanical wear-and-tear phenomenon rather than OA. Certainly, as soon as anyone does any kind of trochleaplasty, the stifle sustains way more damage than might have accrued with the local chondral erosion or low-grade OA.

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224783#224783"]if a dog is 'pain free' but does that thing of skipping occasionally on one back leg[/quote]

I assume that any lameness is suggestive of discomfort/pain. However, a judgement call is needed - first to decide whether the skipping is caused by patella luxation. A great many completely normal terriers have variably intermittent skipping gaits. If that is all there is, even if the patella can be manually lunated then that isn't enough to move me to surgery. If there is progression in terms of severity/disability or if there s evidence of significant pain and/or crepitus in the stifle then surgery can be be considered.

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224783#224783"]I usually did a tibial crest translocation[/quote]

So did/do I.

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224783#224783"] You seem to be saying that unless the dog shows some distress or pain that you'd leave the joint alone? [/quote]

Yes. If there ISN'T any lameness or discomfort, how might you know that your surgery has been successful? Far too much emphasis is placed on the finding of a patella that can be made to luxe during palpation and stifle manipulation. That kind of 'patellar stability' is not a reliable indicator of functional normality or abnormality. It should never be used as an endpoint for treatment.

RE: Luxating patella in young dog

David Mills — Fri, 07 Aug 2020 20:09:21 GMT

Trochleoplasties should be consigned to the dudtbin of veterinary medicine. How anything do traumatic could be considered useful defies my logic. Still happen though, frequently, at referral centres.

MPL as said is a biomechanical abnormality and so TCTs are the treatment of choice mainly for me. When/if to operate? Is it painful rather than mechanical, is it debilitating in terms of function. I'd estimate we operate on less than 1pc of MPLs, excluding traumatic.

RE: Luxating patella in young dog

Julian Earl — Fri, 07 Aug 2020 18:52:55 GMT

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224783#224783"]

You seem to be saying that unless the dog shows some distress or pain that you'd leave the joint alone? Or am i misunderstanding?

Thank-you!

[/quote]

No, not misunderstandingIthink... I tend to agree with that. If the luxation does not appear to trouble the dog via pain and/or loss of mobility, why operate?. If the dog can get around painlessly then anything we do cannot improve on that, can it? As long as my belief that the risk of OA developing is i=overstated! is accurate I stand by not interfering until a clear problem is identifiable.

RE: Luxating patella in young dog

Gillian Mostyn — Fri, 07 Aug 2020 14:57:16 GMT

Malcolm Ness

I am unlikely to do these surgeries as I did very few before, and am now a locum, but would like to know which ones should be redirected to an ortho! I always assumed (possibly incorrectly) that a patella that luxates frequently is likely to result in OA in the future? So if a dog is 'pain free' but does that thing of skipping occasionally on one back leg, or otherwise indicates the patella is luxating, then I usually refer them on. (And when I did surgery, I usually did a tibial crest translocation). You seem to be saying that unless the dog shows some distress or pain that you'd leave the joint alone? Or am i misunderstanding?

Thank-you!

RE: Luxating patella in young dog

Malcolm Ness — Fri, 07 Aug 2020 13:19:27 GMT

As Julian and Beats imply, we need to know more - the functional status of the dog is the key information. Many dogs have patellas that are unstable on palpation/manipulation yet function perfectly adequately during locomotion. Patellar laxity and patellar luxation are not synonyms and neither is there any evidence that a lax patella will progress to luxation.

There is a plethora of surgical options many of which can be disregarded. Surgery is only indicated if there is evidence of stifle pain or lameness. I am thoroughly unconvinced by the suggestion that 'mild' cases progress and should therefore be treated early. Certainly some mild cases do progress but many, probably most do not. If it isn't broken, don't fix it.

I select the least aggressive surgery that I think likely to restore function. Invariably I go for something that redirects the patella - tibial crest translocation is by far the most useful procedure being simple, inexpensive and very frequently effective. I avoid (like the plague) trochleaplasties. These do little other than make the surgeon fell better about the patella being "stable" (see comments above about laxity vs luxation). I was involved in a small way with the development and early evaluation of the Ridgestop implant and that is a potentially useful addition to the list of valid surgical options. Ridgestop has been presented in a couple of international surgery meetings and there is at least one case-series published. Some referral surgeons hate it, apparently because its efficacy renders their more aggressive and costly operations redundant in many cases. I never use soft tissues reconstructions (capsular overlap etc) - even if the modified capsule can be got to heal in the place you left it at the end of surgery, bear in mind that mammalian soft tissues are collagen based and collagen responds to tension by stretching. Soft tissue reconstruction without an alteration to the mechanics will inevitably stretch back to where it used to be.

In summary, for this dog, I would trial it on six weeks of NSAIDs and full activity to get an idea of whether/how much of a problem any patella luxation might be. If there is a clinical problem then surgery can be considered - careful clinical assessment is still the cornerstone of evaluation and decision-making. Plain radiographs allow the appraisal of other potential causes of lameness. Complex and 3-D imaging is rarely, if ever, truly necessary.

RE: Luxating patella in young dog

Julian Earl — Thu, 06 Aug 2020 22:59:37 GMT

[quote userid="2457" url="~/001/veterinary-clinical/small-animal/f/misc-clinical-discussions/29271/luxating-patella-in-young-dog/224743#224743"], as once OA develops it is too late to fix.[/quote]

I agree with that Gillian but is OA inevitable for this? I am not convinced. If the patella is very loose there seems to be very little erosive pressure on the patella or the condyles' so I think the OA-risk can be overstated. For me it is more important how well or otherwise the leg functions at exercise etc.

RE: Luxating patella in young dog

Beats — Thu, 06 Aug 2020 18:54:15 GMT

Hi Derek, I think my answer is "it depends". I'm not an expert, but if you give more information you might get more responses from those in the know:

What weight / type of dog?

Is the patella luxating medially or laterally?

Is the dog affected at all? If so is in what way (eg once a week lifts leg and skips a few steps vs walks with bendy leg permanently and can't jump etc.)

Is it one patella or both?

Is it's prior history known (is it definitely 2.5 years old or just a guess?) and if so has it been having problems from eg 8mths of age or only recently?

Is the patella normally in place and can be pushed out manually and then stays out or pops back in when move leg? Or is it permanently fixed out of position and can't be manually returned to the groove at all? Or any other description of what happens?

Could the dog be adequately confined after surgery if done? If so, would this have any detrimental effects (eg on behaviour)?

All those things would factor into my non-expert decision making.

RE: Luxating patella in young dog

Gillian Mostyn — Thu, 06 Aug 2020 18:44:40 GMT

Whereas I'd say that if the patella luxates 'easily' then I recommend surgery while young, as once OA develops it is too late to fix.

There isn't a 'one size fits all' solution, the need for surgery depends on the type of luxation, cause and degree.

RE: Luxating patella in young dog

Julian Earl — Thu, 06 Aug 2020 14:53:03 GMT

My latest thoughts are askng...: Is it affecting the dog in any way? Specifically does it appear painful? can the dog still walk and run adequately? Any indication of arthritis developing through the abnormal load and wear and tear yet? If it is not troubling the dog, why do anything just yet?