Skipping the Scope: Long-Term Results of HTO for Canine Cruciate Disease

Routine stifle exploration during canine cranial cruciate ligament surgery sounds like common sense, until you ask the uncomfortable question: what if “doing more” doesn’t reliably improve long-term function for most dogs? We sit down with Dr. Dan Low to unpack long-term outcomes after high tibial osteotomy procedures (TPLO and CCWO) performed without routine arthroscopy or arthrotomy and without proactive meniscal evaluation, a real-world approach many clinicians use but rarely see studied in depth.

We break down what high tibial osteotomy actually changes in the cruciate-deficient stifle, then get practical about evidence. Dan explains why this large case series matters, how uncommon events become easier to estimate with bigger numbers, and why validated owner-reported tools like LOAD (Liverpool Osteoarthritis in Dogs) and the Canine Orthopedic Index give us a more standardized view of recovery than vague “good” or “excellent” labels. We also discuss one of the most debated points in veterinary orthopedics: late meniscectomy. When a meniscal sparing strategy produces a low late-intervention rate that looks similar to rates reported in explored joints, it raises a bigger issue about which meniscal lesions are truly clinically meaningful.

We don’t pretend one study settles the debate. You’ll hear the strongest criticisms of this design, the patient groups where exploration still makes sense (uncertain diagnosis, revision cases), and the unanswered research questions that could reshape how we balance morbidity, time, and cost in dog knee surgery. If you treat CCL disease, refer cruciate cases, or counsel owners through surgical options, this conversation will sharpen how you explain risk-benefit decisions without defaulting to habit.

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JAVMA article: https://doi.org/10.2460/javma.25.11.0736

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Transcript

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Welcome And Study Overview

Lisa Fortier 0:31

Welcome to Epic Award-winning Veterinary Vertex, the Aviumated Journal's podcast where we delve into behind-the-scenes look with manuscript authors. I'm editor in chief Lisa Fortier, joined by associate editor Sarah Wright. Today we're discussing a very common affliction in small animals, especially dogs, cranial cruciate ligament disease, and the long-term outcome of HTO or high tubial osteotomy without stifle exploration with our author Dan Lowe. Thank you for joining us, Dan.

SPEAKER_04 1:00

Thank you for having me. Thank you to AVMA Journals and the editorial team for the invitation. I'm very pleased to represent this work on behalf of my co-authors whose contributions made the study possible.

Why Question Routine Joint Exploration

Lisa Fortier 1:11

Awesome. We love a good team. Dan, what I really love about your manuscript is in this day of increasing cost of health care for our animals, I love that you looked at high tibia osteotomy without routine arthroscopy or meniscal evaluation. What motivated you to look at that?

SPEAKER_04 1:30

Yes. So the surgical approach itself, the meniscal sparing approach, isn't new. And surgeons have been using this meniscal sparing strategy for many years. It is definitely uncommon, less common than traditional joint exploring strategies. But what motivated us to conduct this study was the mismatch between clinical practice and the available evidence. Despite this being used, there's relatively very little published work on the long-term outcomes, apart from a study in JSAP in 2017, which only reported subjective outcomes.

Sarah Wright 2:04

Dan, traditionally, many surgeons perform concurrent stifle exploration during cruciate surgery. What clinical observations led you to question whether that approach is always necessary?

SPEAKER_04 2:15

So this question arose from the accumulated clinical experience amongst several surgeons over many years, surgeons before Myself. These surgeons observed that dogs often achieve good outcomes after stifle stabilization with high tibio osteotomy, regardless of whether the joint was explored or the meniscus was treated or not. So that naturally raises the question: if an additional procedure increases surgical time and potential morbidity, is it always providing a meaningful benefit? Importantly, this approach isn't unique to our institution. There are many surgeons in different countries working in different institutions across private practice and academia that have also independently adopted similar meniscal sparing approaches because, in their experience, they also seem to reach the same practical conclusion that starting off with joint exploration and moving towards a menuscal sparing approach hasn't led to a difference in outcomes based on subjective clinical experience.

High Tibial Osteotomy Explained

Lisa Fortier 3:16

Yeah, I love that you're putting evidence behind eminence. For listeners, Dan, who might not be familiar with a high tibial osteotomy, can you briefly explain what it is and how what it does to the mechanics of the joint to it for horses, for dogs with cranial cruciate ligament disease?

SPEAKER_04 3:35

Of course. So high tibial osteotomy is an umbrella term that refers to procedures such as the tibial plateau leveling osteotomy or the cranial closing wedge ostectomy, TPLO and CCW. And these procedures stabilize the cranial cruciate deficient stifle by altering the geometry of the proximal tibia and therefore neutralizing the cranial tibial thrust during weight bearing. There are other high tibial osteotomies out there, such as the Cora-based leveling osteotomy, but our study only included TPLO and CCWO. Although there are slight technical and biomechanical differences between all the high tibial osteotomies, they fundamentally share the same goal, which is to eliminate cranial tibial thrusts.

Why A Large Case Series Matters

Sarah Wright 4:23

Dan, your study included a fairly large cohort of dogs and stifles. What strengths does that provide when evaluating long-term outcomes?

SPEAKER_04 4:32

Yep. So this study was a very large case series compared to other case series that we might see in the veterinary orthopedic literature. Therefore, this allowed us to robustly describe long-term outcomes as well as uncommon events from the large numbers. Uncommon events such as subsequent menisectomy were not common in our cohort, but because of the large numbers, we can be fairly confident of this estimate that we report. While this wasn't a controlled study, the sample size improves confidence in the consistency and the generalized generalizability of our observations.

Using LOAD And COI For Outcomes

Lisa Fortier 5:08

Alequhis said earlier that most of the other studies rely on subjective evaluation. And in your study, you used a validated owner-reported outcome measure, including load and the canine orthopedic index. What does that do for the listener, for the confidence in your data, so that people can really believe this and move forward?

SPEAKER_04 5:27

The limitation of clinician assessment is that this is an inherently subjective and imprecise way to measure an outcome. Many early studies after high tibor osteotomy, and in fact, many other orthopedic studies not looking at cranial crucial ligament disease have used subjective clinician or owner assessment to report these outcomes. Invariably, lots of the time, good or excellent outcomes are reported regardless of surgical technique or approach. And this limits our ability to compare between studies as well as to make any quality improvements with what we're doing. On the other hand, we used the LOAD and the COI questionnaires, which stand for the Liverpool osteoarthritis in dogs questionnaire and the canine orthopedic index, respectively. These are validated outcome measures, and they have been shown to be correlated with force plate data. So in the absence of actually getting the dogs back to walk on the force plate, this can be used as a proxy for how well the dogs are actually walking. While these are definitely not perfect by any means because of the nature of owner questioning as well as the limitations of remote assessment, they provide a more standardized and reproducible way for us to evaluate outcomes and to make comparisons between studies, which is much better than us saying we had 236 typhos and all of them did well.

Late Meniscectomy Rates And Meaning

Sarah Wright 6:46

Dan, one of the most interesting findings was that only a relatively small percentage of dogs ultimately required menisectomy. Did that align with your expectations going into the study?

SPEAKER_04 6:57

Yes. So as mentioned earlier, this meniscal sparing approach has been practiced by myself and my colleagues as well as other surgeons elsewhere, and these results aligned with our expectations and clinical experience. We reported an overall 5.5% rate of late menasectomy, all performed because of a late onset late lameness that did not respond to medical management. This approximately 5% rate of late intervention is actually remarkably consistent across studies and is not something that only we have reported. Other studies employing stipole exploration at this time of high tibial osteotomy also report about 5% rates of late meniscal injury. Of course, their approach is slightly different and they're a little bit more proactive towards removing the meniscus. The 2017 JSAP paper from France also reported a 6% rate of late lameness, which they attribute to undiagnosed clinically significant meniscal lesions. Because of this remarkable consistency across many studies, this raises an interesting question. If the late intervention rate remains similar, regardless of your initial exploration strategy, whether you explore the joint or not, perhaps many untreated meniscal lesions are actually clinically well tolerated.

How Findings Challenge Surgical Planning

Lisa Fortier 8:13

Yeah, ultimately there was really no difference in long-term owner-reported outcome between dogs undergoing menisectomy and those who never had a stifle explorer. How does that uh challenge current surgical planning?

SPEAKER_04 8:26

Yes, so our paper is in direct opposition to the traditional school of thought, which believes, firstly, that all concurrent meniscal lesions at the time of diagnosis and treatment are significant and require um addressing, either by meniscal repair or by partial menisectomy. Secondly, um it challenges the idea that all late meniscal lesions are significant and require treatment. We recognize that our study did not confirm the presence of concurrent meniscal lesions at the time of high tibio osteotomy, and we did not confirm late meniscal lesions when we manage these dogs with a meniscal sparing approach. But we do show that overall, when you take this meniscal sparing approach, uh, this algorithm, if you like, to managing dogs in this fashion, uh, where we intentionally leave many meniscal lesions in situ, this did not lead to any ongoing lameness and poor function, as reported by our load and our COI scores.

Risks, Criticisms, And Study Limits

Sarah Wright 9:23

Yes, it's great information for our listeners. Thank you. What are the potential risks or criticisms of a meniscal sparing approach and how do you address those concerns?

SPEAKER_04 9:32

So, a fair criticism of this study is that this was an observational study instead of a comparative trial. What we did not have was a control group where uh meniscal lesions were diagnosed and treated. So we cannot conclude that meniscal treatment is harmful or unnecessary in all cases. Uh, the concern that's often raised, as mentioned in an earlier response, is that untreated lesions may result in ongoing pain or dysfunction. What our data did suggest was that at least at the population level, when looking at all the stifles as a whole, intentionally avoiding exploration did not appear associated with poor long-term owner-reported outcomes.

When Stifle Exploration Still Makes Sense

Lisa Fortier 10:14

Yeah, really fascinating. Um, now that you've accumulated all this data, are there specific patient populations or characteristics that you would still strongly recommend stifle explore at the initial surgery?

SPEAKER_04 10:27

Yep. So, as mentioned earlier, this study did not perform any preoperative patient selection. So a strength of the study was that we um report consecutive cases treated with this meniscal sparing approach. So no preoperative selection. Um, and all siphons treated were naive to surgery with naturally occurring craniocrucial ligament disease. Uh, diagnosis was made either on a clinical examination andor on uh plain radiography. So for any dogs that don't fit this um these criteria, we we might um this study might not apply. Um so what I mean by that are cases where the diagnosis is uncertain from the preoperative examination or preoperative imaging, then a diagnostic arthrotomy or arthroscopy may be necessary to make your diagnosis, and therefore the results will not apply. Um other cases which may have already had surgery, whether it's um extracapsular stabilization, um tibot tuberosity advancement, or another high tibio osteotomy, and if we're performing a revision surgery, then um the results of our study may not apply, and you may want to consider a diagnostic or a therapeutic arthrotomy for whatever reason.

Biggest Unanswered Meniscus Questions

Lisa Fortier 11:39

So when looking now that you've done all this, when you're looking ahead, what additional studies, I know controlled study you've said a couple of times, or unanswered questions, do you think are more most important for refining uh cranial cruciate ligament disease?

SPEAKER_04 11:52

Yes. So the major unanswered question isn't whether meniscal lesions exist. We know that they do, and uh we know that um we do agree with um the other opposing school of thought. Uh all of us are of the same um opinion in that meniscal lesions exist and they they definitely do cause pain and lameness. Where we disagree is how to go about treating them, um, which lesions are clinically meaningful and which lesions truly benefit from treatment. We do briefly discuss um in the discussion uh the six unanswered questions um regarding uh crucial ligament disease and menasectomy. What we do not know from the available literature or our study is we do not know which meniscal lesions are clinically significant, which meniscal lesions may benefit from treatment at the time of high tibial osteotomy or later on if they're not doing well. We do not know what is the long-term functional impact of joint exploration and menisectomy. We do not know what is the natural progression of an in situ meniscal lesion. We don't know whether an in situ meniscal lesion leads to a different outcome compared to menisectomy. And finally, um to summarize, we we don't know what is the overall risk-benefit of exploring the joint and treating the meniscus versus not exploring and not treating the meniscus.

Cost Differences Between Arthrotomy And Arthroscopy

Lisa Fortier 13:16

I realize it was a multi-u-author study, and this wasn't one of the outcomes, but do you have an estimate on what the financial differences are?

SPEAKER_04 13:25

Yeah, so the financial differences would depend on what your approach is to um exploring the stifle, and this may vary depending on where you practice. Um as far as I'm aware, in the in North America, it is more common to perform arthroscopy compared to arthrotomy, whereas over here in the UK and in Europe, it's more common to perform uh arthrotomy instead of arthroscopy. Um and each of those has their own pros and cons, as well as uh being of different uh procedure lengths. So arthroscopy, because it may take a little bit longer, and because of the equipment required, um depending on what your pricing structure is, there may be a bigger difference if you were already an arthroscopy practicing surgeon.

Take-Home Message And Closing

Sarah Wright 14:11

Dan, you've shared a lot of great information today. And what I really want to do is just boil it down for our listeners so they can come away with a good take-home message. So, in like a very short summary, what's one thing veterinarians should know about your study?

SPEAKER_04 14:25

So I think the biggest take-home message is that not all meniscal lesions are clinically significant and that every procedure we do has procedure time as well as a morbidity. So it's just uh thinking about the risk-benefit of any procedure that we do before we do it. Our study is not suggesting that you should stop exploring every single joint, but that everything that we do there has an um has a cost to it as well.

Lisa Fortier 14:52

That's a great summary. Thanks, Dan. And thanks for taking your time out of your busy schedule to join us today.

SPEAKER_04 14:57

Thank you very much for having me. It was a pleasure.

Lisa Fortier 15:00

For listeners and viewers, you can read Dan's article in Jabma. I'm Lisa Fordier with Sarah Wright. Be sure to tune in next week for another episode of Veterinary Vertex. And don't forget to leave us a rating or review on Apple Podcasts or wherever you listen.