Simini Surgery Review: Equine Edition

Veterinary Surgery Deep Dive: Equine Ortho — October 2025 Edition

Simini Podcasts Season 1 Episode 12

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In this episode of the Simini Equine Surgery Podcast, we explore the orthopedic research from the October 2025 issue (Issue 7) of Veterinary Surgery, where two complementary studies examine the future of equine cervical vertebral fusion. Together, they answer two fundamental questions: Which implant performs best mechanically? And how do horses actually perform after surgery? 

This episode follows the evolution of cervical fusion—from decades of clinical experience using the kerf cut cylinder (KCC) to emerging 3D-printed titanium plate-and-spacer technology designed to improve construct stability and long-term outcomes.

In this episode:

 ✅ Cormier et al. — Evaluated intra-articular injection of decellularized porcine amnion/chorion suspension in horses. Both low- and high-dose groups developed inflammatory responses, but the high-dose group had more clinically evident inflammation, including increased lameness, elevated synovial and systemic SAA, and persistent signs requiring lavage and flunixin in some horses. The study concluded that dPACLS at the tested doses is not recommended for intra-articular injection because of the inflammatory response. 

Janicek et al. present the largest multicenter evaluation of C7–T1 ventral interbody fusion using the kerf cut cylinder implant. Reviewing 38 horses treated over a 20-year period, the authors reported an 89% hospital discharge rate, with 79% achieving successful long-term outcomes. Half of the horses returned to athletic work—including dressage, show jumping, barrel racing, hunters, and western pleasure—while many others regained comfortable pasture soundness. The study also provides valuable surgical pearls for one of the most anatomically challenging regions of the equine cervical spine and highlights laryngeal spasm as the most significant perioperative complication requiring careful airway management. 

Zedler et al. evaluated a 3D-printed titanium plate and spacer construct against the traditional 4.5-mm locking compression plate (LCP) in an ex vivo biomechanical model of C4–C5 fusion. Although both constructs demonstrated similar stiffness and failure loads, the 3D implant was significantly less likely to fail through displaced vertebral fracture or screw pullout during extension loading. The findings suggest that modern patient-specific implant design may improve mechanical reliability while providing a scaffold for future osseous integration. 

Together, these studies illustrate how clinical experience and engineering innovation are converging to improve treatment options for horses with cervical vertebral stenotic myelopathy (CVSM). Long-term outcomes demonstrate that cervical fusion is no longer simply a salvage procedure—it is increasingly becoming a realistic path back to athletic performance for appropriately selected horses. 

🎓 Journal Articles Discussed

  • Cormier et al.Inflammatory Response Following Intra-Articular Injection of Decellularized Porcine Amnion/Chorion in Horses
    Janicek et al.Multicenter Results for C7–T1 Ventral Interbody Fusion in Horses Using the Kerf Cut Cylinder
    Zedler et al.Ex Vivo Biomechanical Testing of a Three-Dimensional Printed Titanium Plate and Spacer Construct and 4.5 mm Locking Compression Plate for Ventral Cervical Fusion of C4–C5 in the Horse

📚 From the October 2025 Issue (Issue 7) of Veterinary Surgery

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SPEAKER_01

Hi, I'm Carl Damiani, and this is the Simene Equine Surgery Podcast, your fast, focused update on what matters most from the latest equine 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 covers the orthopedic section from the October 2025 issue of veterinary surgery with three studies exploring very different aspects of equine orthopedic practice, from biologic therapies to cervical spine surgery and next generation implant technology. First, we'll examine a study by Cormier et al. evaluating the inflammatory response after intra-articular injection of a decellularized porcine amnion chorion product. As biologic therapies continue to gain popularity, this paper offers an important reminder that not every regenerative treatment is biologically benign and highlights the need to carefully evaluate safety before adopting new products into clinical practice. Next, we'll review Janichek et al. who present the largest multi-center case series to date on C7 to T1 ventral interbody fusion using the curf cut cylinder. We'll discuss the unique anatomical challenges of this procedure, the complications surgeons should anticipate, and the long-term outcomes that suggest cervical fusion can provide meaningful functional recovery for many horses with cervical vertebral stenotic myelopathy. Finally, we'll look at Zedler et al. who compare a novel 3D printed titanium plate and spacer construct with a traditional locking compression plate in an ex vivo biomechanical study. Their findings provide an early glimpse into how patient-specific implant design may improve construct stability and help shape the future of equine cervical stabilization surgery. Three studies, three very different approaches to improving outcomes, from regenerative medicine and biologics to advanced spinal surgery to the next generation of implant technology. Let's dive

Cormier et al. Study: Evaluating the inflammatory response and safety of intra-articular injections of a cross-species decellularized porcine amnion chorion product (DPAC-CLS) in horses.

SPEAKER_01

in.

SPEAKER_02

Welcome to the deep dives. You know, our mission here is extracting actionable real-world surgical intelligence from recent data so you can actually apply it tomorrow in the LR.

SPEAKER_00

Right, exactly. And today we are looking at a really fascinating clinical challenge.

SPEAKER_02

Yeah, so imagine you inject a biological treatment, right, like an amniotic suspension into an injured joint. You expect this soothing, natural fire blanket to calm the inflammation.

SPEAKER_00

But when you cross species lines with these biologics, well, that blanket doesn't just fail. The body's immune system misinterprets it as a full-scale invasion.

SPEAKER_02

Right. Suddenly your treatment is the fire. So we're unpacking when a regenerative biologic backfires, and what that means for you, the surgeon trying to clean up the mess.

SPEAKER_00

Exactly. We're pulling this from a recent paper, Cormier et al. 2025. And the researchers were testing a specific off-the-shelf product called DPAC CLS.

SPEAKER_02

Which stands for dehydrated porcene, amniotic chorion, and liquid suspension, I think.

SPEAKER_00

Yeah, that's right. It's essentially a pig-derived amniotic fluid and membrane product. They wanted to see if it could be safely injected into the radiocarpal joints of horses.

SPEAKER_02

The main knee joint, basically.

SPEAKER_00

Right. So 10 adult horses got a high dose,

Xenogeneic Immune Rejection: Explaining how distinct surface proteins like the alpha-gal sugar molecule trigger a severe immune response despite traditional amniotic immune privilege.

SPEAKER_00

um, 50 milligrams in one joint, or a low dose of five milligrams, with standard saline in the opposite joint as a control.

SPEAKER_02

Aaron Powell Okay, hold on. I need to push back on the premise here for a second. Yeah. Because across medicine, amniotic tissue is heavily prized, specifically because it lacks the major antigens that trigger an immune response.

SPEAKER_00

Aaron Powell Yeah, it's considered immunologically privileged.

SPEAKER_02

Exactly. So why would using pig amniotic tissue in a horse trigger an alarm system? Shouldn't just, you know, fly under the radar?

SPEAKER_00

Well, you'd think so, but that immune privilege isn't absolute when you make xenogenaic jump, when you cross species lines.

SPEAKER_02

Aaron Powell Oh, so the pig tissue still has something the horse recognizes.

SPEAKER_00

Aaron Ross Powell Right, precisely. It carries distinct surface proteins like the alpha gol sugar molecule, which horses naturally have antibodies against.

SPEAKER_02

Wow. Okay. So instead of a soothing balm, the immune system just attacks it.

SPEAKER_00

Right. Local macrophages and T cells just flood the joint space. It turns a regenerative therapy into a massive inflammatory battleground.

SPEAKER_02

Aaron Powell So what did that actually look like in the data? I mean, how bad was the reaction?

SPEAKER_00

It was severe. I mean, both doses caused inflammation, but the 50 milligram high dose was intense. The synovial fluid nucleated cell counts peaked at over 81,000 cells per microliter.

SPEAKER_02

Aaron Powell Wait, 81,000? That's just a swarm of white blood cells.

SPEAKER_00

Yeah, it is. And systemically, serum amyloid A, which the liver pumps out during severe inflammation, spiked to over 810 micrograms per milliliter.

SPEAKER_02

Those numbers translate to a real problem on the floor because at what, 168 hours post-injection, several of those high-dose horses were persistently lame, right?

SPEAKER_00

Yeah, they were positive to carpal flexion. They couldn't just walk this off.

SPEAKER_02

So the clinicians actually had to step in and surgically intervene.

SPEAKER_00

Exactly. And the clear clinical takeaway from Cormier et al. 2025 is that at these doses, this specific porcene amniotic product is just not recommended for intraarticular injection. The xenogenic rejection is just too severe.

SPEAKER_02

So let's look at that clinical intervention. To stop that massive

Simini Protect Lavage Study: Contrasting standard saline's 42% bacterial remainder with a 60-second surfactant alternative that achieves total biofilm disruption and clearance at closure.

SPEAKER_02

inflammatory cascade, the researchers had to physically flush the joint out with a lavage.

SPEAKER_00

Right, which brings up a really crucial, somewhat hidden mechanical issue in everyday surgery.

SPEAKER_02

Yeah, because when a joint is compromised, whether it's a biologic gone wrong or, you know, a bacterial infection, the standard default is to flush it with saline.

SPEAKER_00

But saline is just a mechanical flush. It relies entirely on fluid pressure to physically push debris out. And independent studies show a major limitation there.

SPEAKER_02

Aaron Powell Right, because saline leaves what, 42% of bacteria behind?

SPEAKER_00

Exactly, 42%. It lacks the chemical capability to penetrate biofilms, which are those sticky polymeric shields bacteria build to anchor into tissue.

SPEAKER_02

So you're leaving nearly half the bacteria behind in a compromised joint just because water pressure isn't enough to break down that biofilm glue. That's wild.

SPEAKER_00

It is. And that's where newer data on Semini Protect Lavage becomes highly relevant for evaluating how we handle closure.

SPEAKER_02

Because simony is a non-antibiotic lavage, right?

SPEAKER_00

Yeah, but instead of just washing over the surface like saline, it uses a specific surfactant combination.

SPEAKER_02

So it chemically dismantles the lipid structures of the biofilms.

SPEAKER_00

Right. And the bacterial cell walls. In those same head-to-head studies, using Simony Protect Lavage for just 60 seconds prior to closure left 0% of bacteria behind.

SPEAKER_02

Wow. So it's like switching from a garden hose to a targeted chemical solvent, and it doesn't even disrupt the existing workflow.

SPEAKER_00

Exactly. It completely changes the risk profile.

SPEAKER_02

Aaron Powell Okay, so for your next caseload, the takeaways are pretty clear. First, treat xenogenaic intra-articular injections with extreme caution. Just because it says amniotic doesn't mean it won't be seen as an invader by a different species.

SPEAKER_00

Right, totally.

SPEAKER_02

And second, scrutinize the mechanics of your closure protocols. If fluid pressure isn't breaking down biofilms, you know, you might need a surfactant approach to actually clear a site.

SPEAKER_00

Which leaves you with this to consider. If a cutting-edge healing biologic can accidentally trigger massive joint destruction over a microscopic protein, and our standard saline flush leaves a 42% blind spot in sterile technique.

SPEAKER_02

What other trusted routine tools in your OR are currently operating on outdated assumptions? Here's the next article.

Janicek et al. Study: A multi-center retrospective review of C7 to T1 ventral interbody fusion using the kerf cut cylinder (KCC) implant in horses.

SPEAKER_02

So picture this.

SPEAKER_00

Oh yeah. Literally fighting the sternum just to get a visual.

SPEAKER_02

Exactly. I mean, your retractor handles are jammed all the way cranially, and uh the trunchus bicarotides is just sitting right in your approach path.

SPEAKER_00

Always right in the way.

SPEAKER_02

Right. And historically, if you're operating down here, you know, you're really just hoping to get the horse past your sound. But what if that restrictive high-risk junction could actually yield a return to top-level performance?

SPEAKER_00

Well, that is exactly the paradigm shift we're looking at today. We are breaking down Janisec et al. 2025.

SPEAKER_02

Okay, tell us about it.

SPEAKER_00

So it's a retrospective multi-center study. They looked at 38 client-owned horses,

Athletic Function and Fusion Outcomes: Reviewing the 79% success rate and impressive 50% return to intended performance disciplines like riding, training, or showing.

SPEAKER_00

and uh all of them underwent a C7 to T1 ventral interbody fusion.

SPEAKER_02

Using the KCC implant.

SPEAKER_00

Exactly, a curve cut cylinder. Yeah.

SPEAKER_02

I mean, a lot of you listening are probably familiar with the KCC, but it's really worth noting why it's chosen for these deep, you know, high load areas. The curve cut is that slotted cylindrical design so it dynamically engages the bone. It's basically a titanium cage that restores disc height, decompresses the cord, and this is the big thing, promotes massive boning growth.

SPEAKER_00

Yeah, exactly. You aren't just like wedging something in there and hoping for the best. You're actively facilitating a biological fusion.

SPEAKER_02

Which is huge.

SPEAKER_00

It really is. And the data from the study proves just how effective that stabilization actually is. So out of the 38 horses, 79% achieved a successful outcome.

SPEAKER_02

Wow. Okay. But give us the real clinical punchline here. Are these horses getting back to work?

SPEAKER_00

Yeah, this is the breakdown that should really catch your attention. 50% return to riding, training, or showing.

SPEAKER_02

Wait, hold on. I have to challenge that 50% ficker.

SPEAKER_00

I know it sounds high.

SPEAKER_02

I mean 50% returning to actual riding and showing. Because down at C7 to T1, just getting the horse to walk off the trailer without a taxi used to be the big win.

SPEAKER_00

Right, absolutely.

SPEAKER_02

Are we talking about true baseline performance here? Or is that 50% just doing like heavily modified, really light work?

SPEAKER_00

No, the study specifically indicates a return to their intended disciplines.

SPEAKER_02

Seriously.

SPEAKER_00

Yeah. So we aren't just talking about light trail walking. This is genuine athletic recovery. And another 29% achieved unrestricted paddock turnout or were in active rehab with improved neuroscience.

SPEAKER_02

That's incredible.

SPEAKER_00

Yeah. Overall, 89% were discharged and alive beyond three months.

SPEAKER_02

Aaron Powell I mean that completely shifts the calculus for this procedure.

Caudal Cervical Anatomical Challenges: Navigating restrictive boundaries near the sternum, handling retractor placement space, and meticulously isolating the truncus bicarotidis

SPEAKER_02

It's the difference between, you know, using duct tape on a fractured foundational beam just to keep the barn standing versus actually installing a solid load-bearing pillar so you can put weight on the structure again.

SPEAKER_00

Aaron Powell That is a perfect way to look at it. But you know, installing that pillar at C7 to T1, it requires navigating some severe anatomical hurdles.

SPEAKER_02

Aaron Powell Oh, for sure. The sternum alone.

SPEAKER_00

Exactly. Like you mentioned earlier, the sternum severely restricts your instrument angle. Surgeons often have to position both retractor handles cranially just to create enough working space to see anything.

SPEAKER_02

Aaron Powell Which is a nightmare.

SPEAKER_00

And then uh you have the truncus bicarotides, which you meticulously have to identify and isolate. It's usually right within or just dorsal to the superficial cervical lymph nodes.

SPEAKER_02

Right. And when you're finding that much anatomy, I mean you

Postoperative Airway Risks and Mitigation: Managing fatal laryngeal spasm risks through reverse Trendelenburg positioning, pre-op endoscopy, and emergency tracheostomy preparation.

SPEAKER_02

have to be putting immense pressure on the surrounding soft tissue just to maintain your surgical window.

SPEAKER_00

Oh, absolutely.

SPEAKER_02

With that much aggressive retraction, I have to imagine the recurrent laryngeal nerve, it's just taking an absolute beating.

SPEAKER_00

You hit the nail on the head. That retraction pressure is exactly why the most critical short-term risk you must anticipate is a fatal laryngeal spasm during recovery.

SPEAKER_02

Fatal.

SPEAKER_00

Yeah, it's a dual threat. You have the mechanical neuropraxia on the recurrent laryngeal nerve from your retractors combined with severe post-op pharyngeal and laryngeal edema.

SPEAKER_02

Because of the deep dissect. So, uh, if the airway is at risk of just closing up the second you pull the tube, how are you preempting this? I mean, we can't just cross our fingers in the recovery stall.

SPEAKER_00

Definitely not. You have to be incredibly proactive, really on three fronts. First, run a pre-op unsedated endoscopy.

SPEAKER_02

Okay. Looking for what?

SPEAKER_00

You're specifically watching that left erotinoid. If it isn't abducting properly, you just assume a pre-existing neuropathy and switch to a left-sided surgical approach.

SPEAKER_02

Ah, to spare the right side. Don't compromise the only good side they have left.

SPEAKER_00

Exactly.

SPEAKER_02

Okay, what about the edema itself? How do we handle that?

SPEAKER_00

You manage that right on the table. Position the horse in reverse Trendelenberg. So elevating the head and neck.

SPEAKER_02

Using gravity.

SPEAKER_00

Right. It uses gravity to actively drain and reduce edema development during the actual hours you're operating.

SPEAKER_02

That makes total sense.

SPEAKER_00

And finally, and this is crucial, you must have an emergency tracheostomy kit open and waiting right at the anesthesia recovery stall.

SPEAKER_02

Open, not just nearby in a cabinet.

SPEAKER_00

Open and ready. These spasms hit rapidly once the endotracheal tube is removed, and honestly, you won't have time to go hunting for a scalpel.

SPEAKER_02

So really, when you look at all this data, the whole approach to CVSM at this junction changes.

SPEAKER_00

It really does.

SPEAKER_02

If we can preempt the airway edema with reverse Trendlenburg and have that track kit ready to go, the KCC implant moves from being a last resort salvage option to, well, a frontline structural fix.

SPEAKER_00

Yes. It actually gives these horses a fighting chance at returning to their athletic careers.

SPEAKER_02

Which is just fantastic news for you and the OR. So that's your take-home message today. But before we wrap up this deep dive, let's look at the bigger picture.

SPEAKER_00

Yeah, it brings up a really fascinating clinical question. Given that 50% return to riding success rate at such a challenging caudal junction, how might adopting this KCC fusion earlier in your diagnostic timeline alter things?

SPEAKER_02

Oh, I see where you're going.

SPEAKER_00

Right. Like how could this alter the career longevity of high-level performance horses? If you intervene before secondary compensatory injuries even have a chance to develop, what could that do for the long-term prognosis of the equine athlete?

SPEAKER_02

Something to think about next time you're evaluating those early neurosigns.

SPEAKER_01

Turning the page.

Zedler et al. Study: An ex vivo biomechanical comparison of a novel 3D-printed titanium plate and spacer construct (3DM) versus a traditional locking compression plate (LCP).

SPEAKER_02

Yeah, that is a great way to picture it.

SPEAKER_00

Aaron Powell Right. So if I'm looking at this 3DM titanium hardware

Comparative Structural Stiffness: Observing highly similar baseline mechanical yield, failure moments, and stiffness parameters between the 3DM and traditional LCP constructs.

SPEAKER_00

as an alternative to the traditional LCP, my immediate assumption is that it just, you know, it must be inherently stiffer and stronger to justify the switch.

SPEAKER_02

Well, you would think so, right. But the data actually shows something completely different.

SPEAKER_00

Aaron Powell Wait, really? It isn't stronger.

SPEAKER_02

No, actually. When measuring yield, failure moment, and overall stiffness, the two constructs were strikingly similar. The 3DM just wasn't inherently stronger in those primary biomechanical metrics.

SPEAKER_00

Okay. Well, if the failure metrics are essentially the same, my first thought as a surgeon is that uh this doesn't change my interoperative plan at all.

SPEAKER_02

I mean that makes total sense.

SPEAKER_00

Right. Because mechanical stability is the primary goal. If both plates hit the same threshold, why go through the hassle of switching hardware?

SPEAKER_02

Because the critical difference isn't when they fail under load, it's how they fail.

SPEAKER_00

Okay, how do you mean?

SPEAKER_02

Well, the clinical punchline of this paper really comes down to extension. When these spines were loaded in extension, the failure modes just diverged completely.

SPEAKER_00

I'm guessing the LCP didn't fare well.

SPEAKER_02

Not at all. In the LCP group, five out of the six tested spines suffered displaced vertebral fractures.

SPEAKER_00

Oh, wow.

SPEAKER_02

Yeah, and four out of seven catastrophic screw pullout.

SPEAKER_00

So just total instability, the bone is basically giving way completely around the hardware.

SPEAKER_02

Exactly.

SPEAKER_00

But considering the 3DM's design, I'd wager it managed those same extension loads much differently.

SPEAKER_02

Aaron Powell It did. Zero displaced fractures.

SPEAKER_00

Of zero?

SPEAKER_02

Zero. And zero screw pullouts, too.

SPEAKER_00

Man, that is a massive shift in the risk profile. You're going from guaranteed bone failure with the LCP to the 3DM just holding its ground.

SPEAKER_02

Aaron Powell It really is a night and day difference.

SPEAKER_00

Aaron Powell I'm trying to visualize why that happens though. If we go back to that heavy barn door analogy, the new construct must be changing how

Geometric Plate Constraints and Screw Mechanics: How a shorter 100 mm plate length and larger 6.5 mm cancellous threads distribute peak extension forces away from weak vertebral body centers.

SPEAKER_00

the stress is distributed across the wood or uh in this case the vertebrae.

SPEAKER_02

Aaron Powell Your analogy actually holds up perfectly when you look at the geometry.

SPEAKER_00

Oh yeah.

SPEAKER_02

Yeah. So a standard LCP is 150 millimeters long.

SPEAKER_00

Okay.

SPEAKER_02

Which means the ends of that place, like the edges of your hinge land right in the center of the vertebral body.

SPEAKER_00

And that happens to be the weakest part of the bone.

SPEAKER_02

Exactly. But the 3DM plate is only 100 millimeters long.

SPEAKER_00

Ah, so it anchors closer to the inner vertebral space.

SPEAKER_02

Right, completely avoiding that weak center.

SPEAKER_00

So you aren't creating a massive stressor riser right in the middle of the vertebra. That makes perfect sense.

SPEAKER_02

It does. And it also comes down to the hardware itself, specifically the screws.

SPEAKER_00

What's the difference there?

SPEAKER_02

Well, the LCP relies on 5.0 millimeter locking screws, but the 3DM construct uses larger 6.5 millimeter cancellous screws.

SPEAKER_00

Right. And a quine vertebrable bone is relatively soft, so I'm assuming those larger cancellous threads just provide significantly better purchase.

SPEAKER_02

Spot on. They distribute the stress so much more effectively, which prevents the screw from just ripping out of the bone when the neck extends.

SPEAKER_00

I mean, that geometric nuance completely changes the risk-benefit analysis for an operation like this.

SPEAKER_02

It really does. It allows you to maintain the necessary stiffness while fundamentally altering how the construct handles peak loads.

SPEAKER_00

So the actionable takeaway for your practice is pretty clear. While 3DM implants offer similar overall mechanical stability to standard LCPs, they drastically reduce the risk of catastrophic screw pull-out or displaced vertebral fractures during neck extension.

SPEAKER_02

Yeah, it's a huge step forward for patient safety in the OR.

SPEAKER_00

For sure. But we do have to remember this was an ex vivo study, right? It was tested without soft tissue support.

SPEAKER_02

Right. That is an important caveat.

SPEAKER_00

Which leaves you with a compelling question for your future cases. We know this porous 3D titanium is designed for in-vivo osteointegration.

SPEAKER_02

Yeah, the bone ingrowth potential is huge.

SPEAKER_00

Exactly. So once that crane is carrying a live load again, how will that capacity for bone integration ultimately impact the long-term success of the fusion and, you know, prevent intervertebral space collapse? Something to think about next time you're scrubbing in for a C-spine.

SPEAKER_01

That's it for this episode of the Semini 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. Thanks for listening, and we'll see you in the next episode.