Veterinary Surgery May 2026 – Ortho Part 2: SDFT Luxation Without Casts & Smarter THR Templating

In this Simini Small Animal Surgery Podcast episode, we continue our orthopedic coverage from the May 2026 issue of Veterinary Surgery by examining two studies that reinforce an important surgical lesson: small technical details often determine long-term success.

One study challenges the traditional reliance on postoperative immobilization following superficial digital flexor tendon (SDFT) luxation repair, while the other evaluates how radiographic positioning influences preoperative templating for canine total hip arthroplasty.

In this episode:

✅ Viskjer et al. — A prospective study evaluating a modified block recession calcaneoplasty for treatment of canine SDFT luxation without routine postoperative tarsal immobilization. All dogs achieved full return to function, with objective gait analysis showing near-normal limb symmetry at long-term follow-up. The study demonstrated that carefully executed sulcus deepening can provide sufficient biomechanical stability without casts or splints, provided adequate calcaneal wall thickness is preserved. The key technical takeaway: maintain approximately 25% of calcaneal width on both the medial and lateral walls to avoid catastrophic fracture and recurrent luxation. 

✅ Zab et al. — A retrospective radiographic study comparing traditional extended hip radiographs with caudocranial flexed hip projections for canine THR templating. The authors found that extended views frequently created a false appearance of a stovepipe femoral canal, underestimating implant size in 88% of cases. Flexed views provided a more realistic representation of femoral canal morphology but tended to slightly overestimate final implant size due to magnification effects. The findings suggest that flexed hip projections may serve as a valuable alternative in dogs with severe osteoarthritis where standard positioning is difficult or impossible. 

Together, these studies demonstrate that successful orthopedic outcomes often depend less on adding complexity and more on understanding the underlying biomechanics and anatomy.

🎓 Journal Articles Discussed

• Viskjer et al. — Surgical management of luxation of the superficial digital flexor muscle tendon (SDFT) using a modified block recession calcaneoplasty without subsequent tarsal joint immobilization
• Zab et al. — Comparison of canine femoral implant templating for total hip arthroplasty on 25 sets of craniocaudal extended and caudocranial flexed hip radiographs 

📚 From the May 2026 issue of Veterinary Surgery

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Transcript

SPEAKER_01 0:04

Hi, I'm Carl Damiani, and this is the Simony Small Animal Surgery Podcast, your fast, focused update on what matters most from the latest small animal surgical literature. In each episode, we break down key articles from the veterinary journals and translate them into surgical insight you can use today, not someday. This episode continues our orthopedic coverage from the May 2026 issue of veterinary surgery, and we're focusing on two studies that highlight an often overlooked aspect of orthopedic success: getting the details right. Whether it's surgical technique or pre-operative planning, small decisions can have a major impact on patient outcomes. First, we'll look at Viskir et al. who describe a novel approach for managing superficial digital flexor tendon luxation in dogs using a modified block recession calcaneoplasty. Beyond the surgical technique itself, the study challenges a long-held assumption in postoperative care by evaluating outcomes without routine tarsal joint immobilization. We'll discuss recurrence rates, complications, and what this may mean for future management of these frustrating tendon injuries. Then we'll turn to Zab et al. who examined femoral stem templating for canine total hip arthroplasty. By comparing traditional hip extended radiographs with flexed hip projections, the authors explore how radiographic positioning influences implant selection. It's a practical study that speaks directly to surgical planning, implant sizing, and the limitations of templating in dogs with advanced hip disease. Two studies, one common theme, precision matters. From tendon stabilization to total hip replacement planning, success often comes down to the finer details of technique, anatomy, and decision making. Let's dive in.

SPEAKER_02 1:57

So, um imagine you just executed like a completely flawless surgical repair.

SPEAKER_00 2:03

Oh, it is the best feeling.

SPEAKER_02 2:05

Right. But then you realize the post-op care is actually what ends up hurting your patient.

SPEAKER_00 2:10

Yeah, that is incredibly frustrating. And uh that is the exact tension you face with superficial digital flexor tendon or STFT luxations in dogs.

SPEAKER_02 2:19

Right, because usually we rely on rigid external coaptation.

SPEAKER_00 2:23

Yeah, casts. Which, you know, frequently cause these severe soft tissue complications.

SPEAKER_02 2:27

Exactly. But today we are diving into a study by Visture et al.

SPEAKER_00 2:35

They did. Basically, they asked, what if we just throw the post-op cast in the trash?

SPEAKER_02 2:39

I mean, I love that. So what was the actual approach here?

SPEAKER_00 2:42

Well, it was a prospective study. The surgical team performed a modified block recession calcaneoplasty on eleven limbs across nine dogs, and they intentionally skipped post-op tarsal joint immobilization completely.

SPEAKER_02 2:54

Okay, wait. If we think of the SDFT like a rope slipping off a shallow pulley, this procedure is like carving a deeper groove for that rope, right?

SPEAKER_00 3:02

Precisely. You are deepening the sulcus so you don't have to lock the whole pulley system down.

SPEAKER_02 3:06

But honestly, as a surgeon, that sounds terrifying. I mean, without a cast during early weight bearing, why doesn't that tendon just pop right back out?

SPEAKER_00 3:15

You would think it would, right. But it comes down to how the bone architecture is actually utilized.

SPEAKER_02 3:21

Okay, how so?

SPEAKER_00 3:22

Well, when you deepen that sulcus, the tendon is securely captured by the bony walls you leave behind. The physical geometry of the calcaneus is doing the mechanical work.

SPEAKER_02 3:33

So it is physically holding the tendon in place rather than relying on a cast to fight the tension.

SPEAKER_00 3:39

Exactly. You just don't need the external immobilization if the bone structure is sound.

SPEAKER_02 3:44

That relies on absolute confidence in your bone cuts, though. Did it actually hold up in the dogs?

SPEAKER_00 3:48

It really did. All dogs in the study achieved a 100% return to full function. Wow.

SPEAKER_02 3:53

100%.

SPEAKER_00 3:54

Yeah. And the objective gate analysis backs that up. They measured a symmetry index using pressure-sensitive walkways. Trevor Burrus, Jr.

SPEAKER_02 4:01

Right, to see how evenly they were walking.

SPEAKER_00 4:03

Exactly. So pre-operatively, the dogs had an asymmetry ratio of 0.20. By the long-term follow-up, that had dropped all the way to 0.05.

SPEAKER_02 4:12

Aaron Powell, which, to put that in perspective for you listening, zero is perfect in visible symmetry. Yeah. At 0.05, you could watch this dog run across the clinic parking lot, and you wouldn't even be able to guess which leg had the surgery.

SPEAKER_00 4:24

It is an incredible result.

SPEAKER_02 4:26

I mean, I love a functional recovery stat like that, but let's be real. Anytime we carve into the calcaneal tuberosity, we risk fracturing it.

SPEAKER_00 4:33

Oh, absolutely.

SPEAKER_02 4:34

So did Vishier's team manage to avoid fractures completely?

SPEAKER_00 4:37

Well, no, not completely. There was one major complication, which was a recurrent luxation.

SPEAKER_02 4:42

Oh, okay. What happened there?

SPEAKER_00 4:44

It actually highlights the single most critical biomechanical rule of this surgery. During the osteotomy, the medial wall of the calcaneal tuberosity was cut way too narrow.

SPEAKER_02 4:54

And it just fractured under the tension of the Achilles mechanism.

SPEAKER_00 4:57

Exactly. It snapped. So the data clearly dictates that you must leave both the medial and lateral walls at approximately 25% of the total width.

SPEAKER_02 5:06

Got it. Because if you shave those walls down past that 25% mark, the tension is just too much for the remaining bone.

SPEAKER_00 5:13

Aaron Powell Right. That 25% thickness is the absolute biomechanical threshold you need to withstand early weight-bearing forces.

SPEAKER_02 5:21

Especially without the support of a cast.

SPEAKER_00 5:23

Exactly.

SPEAKER_02 5:24

So this entire procedure is really an exercise in eliminating post-op vulnerabilities.

SPEAKER_00 5:28

It is. You leave the cast off to avoid soft tissue damage, and you meticulously leave those bone walls thick to avoid fractures.

SPEAKER_02 5:35

Aaron Powell But you know, there is a third microscopic vulnerability we leave behind in the OR every single time we close a site.

SPEAKER_00 5:42

Ah, yes. The bacteria are standard saline flush simply doesn't wash out.

SPEAKER_02 5:47

Right. I mean, saline is a massive blind spot in standard infection control, isn't it?

SPEAKER_00 5:52

Aaron Powell It really is. Independent head-to-head studies show that saline actually leaves 42% of bacteria behind in the surgical site.

SPEAKER_02 5:59

Aaron Ross Powell 42%. That is a staggering delta to leave to chance, especially when you are closing up a highly loaded orthopedic site like a calcaneus.

SPEAKER_00 6:07

Aaron Powell, which is exactly why relying solely on saline is being heavily re-evaluated right now.

SPEAKER_02 6:12

Enter Semini Protect Lavage.

SPEAKER_00 6:14

Yes, exactly. Simony Protect Livage is a non-antibiotic lavage designed to address that specific gap.

SPEAKER_02 6:20

Aaron Powell So how does it compare to saline?

SPEAKER_00 6:22

Well, in those same head-to-head studies, while saline left that 42% of bacteria behind, simony protect lavage left zero percent. Oh, zero. Yeah, it acts as an evidence-informed protocol adjustment, and it is specifically suited for orthopedic primary and revision surgeries, targeting exactly what saline misses.

SPEAKER_02 6:41

Aaron Powell And you use it just before closure, seamlessly integrating it into your workflow in under 60 seconds.

SPEAKER_00 6:47

Right. It is super fast.

SPEAKER_02 6:48

You just need to keep in mind the clinical contraindications. So uh it is not for use in eyes, ears, the abdomen, or the thorax.

SPEAKER_00 6:55

Yeah. But otherwise, it is all about controlling what you leave behind in the surgical site so the patient can actually heal.

SPEAKER_02 7:01

Aaron Powell Bringing this back to the big picture of ViscGiridal 2026, a meticulously planned modified block recession calcaneoplasty allows you to safely ditch the cast for SDFT luxations.

SPEAKER_00 7:13

Which removes those frustrating coaptation complications entirely from the equation?

SPEAKER_02 7:17

Aaron Powell You fix the pulley, ensure the walls are 25% thick to handle the biomechanical load, and just let the anatomy do the work.

SPEAKER_00 7:24

It is a game changer for sure.

SPEAKER_02 7:25

Which leaves you with this final thought. If this study proves that mandatory post-op immobilization for SDFT luxations is really more of a habit than a necessity, what other established surgical traditions in your daily practice might actually be holding your patients back?

SPEAKER_01 7:45

Let's explore another relevant study.

SPEAKER_02 7:52

You know that feeling when you're uh you're scrubbing in for a canine total hip arthroplasty, right?

SPEAKER_00 7:58

Oh, yeah, and you're staring down your pre-op plans.

SPEAKER_02 8:00

Exactly. But the patient has like severe osteoarthritis, and you just know you can feel it, that the templated femoral stem size is lying to you.

SPEAKER_00 8:11

It's an incredibly common or our frustration. I mean, really common.

SPEAKER_02 8:15

Yeah. And so when joint disease prevents that full extension, standard craniocaudal extended views just become, well, notoriously unreliable.

SPEAKER_00 8:23

Aaron Powell They really do. And that is exactly what we are tackling in this deep dive.

SPEAKER_02 8:27

Aaron Powell Right. So what's the mission today? What are we looking at?

SPEAKER_00 8:29

Aaron Ross Powell So we're looking at a really interesting retrospective radiographic study. It's 25 dogs published by Zob et al. 2026.

SPEAKER_02 8:36

Aaron Ross Powell Okay, 25 Dogs.

SPEAKER_00 8:38

Yeah. And the mission of the study is to see if uh codocranial flexed hip radiographs can actually serve as a reliable interchangeable alternative.

SPEAKER_02 8:46

Aaron Powell You know, for templating when you simply cannot get that leg to extend.

SPEAKER_00 8:49

Aaron Powell Precisely. Because we all know the extended view fails us in severe OA cases. But um why exactly does it fail?

SPEAKER_02 8:56

Aaron Ross Powell Well think of it like okay, try to imagine measuring the length of a pencil. Okay. A pencil. Aaron Ross Powell But you're trying to measure it by looking at its shadow while the pencil is tilted towards you.

SPEAKER_00 9:06

Aaron Powell Oh, right. So the shadow makes it look artificially short and thick.

SPEAKER_02 9:09

Aaron Powell Exactly. That foreshortening effect, that's exactly what is happening to the femur on the radiograph.

SPEAKER_00 9:15

Aaron Powell Yeah. And the data in ZAB et al. 2026 completely backs that up, by the way.

SPEAKER_02 9:20

Aaron Powell Really? How so?

SPEAKER_00 9:21

Aaron Ross Powell Well, this geometric distortion artificially lowers the canal flare index or uh the CFI.

SPEAKER_02 9:27

Aaron Powell Right, the CFI.

SPEAKER_00 9:28

Yeah. And get this 88% of the extended projections in this study falsely presented a stovepipe femoral canal.

SPEAKER_02 9:36

Aaron Ross Powell Wait, 88%? That's massive.

SPEAKER_00 9:38

Massive, meaning a CFI of 1.8 or less.

SPEAKER_02 9:41

Aaron Ross Powell Wow. And I mean, because a stovepipe looks like a straight cylinder rather than a normal, you know, tapered funnel, it makes total sense why surgeons get nervous.

SPEAKER_00 9:50

Oh, absolutely. You look at that straight cylinder on the film and you're terrified of wedging a larger tapered stem into it.

SPEAKER_02 9:56

Aaron Powell Because you fear you'll just shatter the cortex during the press fit.

SPEAKER_00 10:00

Exactly. So you end up artificially underestimating the stem size out of, well, just an abundance of caution.

SPEAKER_02 10:07

Aaron Powell It's basically an optical illusion misleading your whole preoperative plan. Aaron Powell It really is. But wait, let me push back on this for a second. Sure, go ahead. If extending the leg foreshortens the image, right, and artificially shrinks, the apparent stem size shouldn't forcing the leg into a flexed position do the exact opposite?

SPEAKER_00 10:26

Aaron Powell That's a great question.

SPEAKER_02 10:28

Aaron Powell Like, doesn't flexing it alter the object film distance and just I don't know, blow the proportions out of the water the other way?

SPEAKER_00 10:34

You're spot on. It does swing the pendulum in the other direction.

SPEAKER_02 10:37

Aaron Powell Okay, so it's not a perfect fix either.

SPEAKER_00 10:39

No, it's not. When you position the leg for a flexed view, you're changing the geometry and you're often increasing the distance between the bone and the detector panel.

SPEAKER_02 10:49

Ah, right. So that creates a magnification effect.

SPEAKER_00 10:51

Aaron Powell Exactly. And the standard calibration marker might not perfectly correct for that. As a result, neither method consistently predicts the final implanted stem size.

SPEAKER_02 11:00

Aaron Powell Wow. So how far off are we talking here? Like what did the final implant sizes actually show compared to the templates?

SPEAKER_00 11:08

Well, the extended views consistently underestimated the clinical implant. They yielded a median templated size of eight.

SPEAKER_02 11:15

Okay. And the flexed views.

SPEAKER_00 11:16

The flexed views, because of that positioning magnification we just talked about, they slightly overestimated the true size, giving a median templated size of nine.

SPEAKER_02 11:25

Aaron Powell Man, it is like trying to find the true shape of an object using two fun house mirrors.

SPEAKER_00 11:31

That's a perfect way to put it.

SPEAKER_02 11:33

Yeah. I mean the extended view mirror gives you this conservative short stovepipe image, while the flexed view mirror stretches it out and makes your template a bit too aggressive.

SPEAKER_00 11:44

Exactly. But, and this is key, the flexed view does remove that dangerous stovepipe illusion.

SPEAKER_02 11:50

Which is huge.

SPEAKER_00 11:51

It's a massive help for visualizing the actual taper. So the clinical punchline for you to take into the OR tomorrow is basically this.

SPEAKER_02 11:57

Laid on us.

SPEAKER_00 11:58

If you cannot get a proper extended projection due to severe OA, the hip flexed view is a highly practical alternative for your pre-operative planning.

SPEAKER_02 12:06

Aaron Powell But you have to go in knowing it's probably going to overestimate the implant size by a fraction, right?

SPEAKER_00 12:11

Aaron Powell Always. You can use the flexed view to give you a more realistic taper, but, and I can't stress this enough, you can never let that 2D template override your intraoperative assessment.

SPEAKER_02 12:21

Aaron Powell Right. You still need that crucial physical press fit feel once you're actually preparing the canal.

SPEAKER_00 12:26

Aaron Powell Exactly. Press your hands in the OR.

SPEAKER_02 12:28

Aaron Powell So true. Well, that leaves us with one final thought to ponder. Given the inherent geometric distortions and magnification errors, we are constantly fighting with these 2D radiographs. How quickly will mobile CT and 3D templating move from a high-end luxury to the absolute mandatory standard of care for veterinary THA planning?

SPEAKER_01 12:52

That's it for this episode of the Simini Small Animal Surgery Podcast. This show is brought to you by Semini Protect Livage, our interoperative lavage developed to target resistant bacteria and biofilms where traditional solutions of saline and post op antibiotics fall short. If you're interested in learning more or trying out your own procedures, you'll find information and links in the show notes. For listening, and we'll see you in the next episode.