VCOT November 2025 – Ortho: Cementless THR, 3D-Printed SI Guides & Tibial Tuberosity Avulsion Outcomes

In this Simini Small Animal Surgery Podcast episode, we conclude our orthopedic coverage from the November 2025 issue of Veterinary and Comparative Orthopaedics and Traumatology (VCOT) by exploring three studies that examine how precision, technology, and long-term adaptation influence orthopedic success.

From a novel approach to cementless total hip replacement, to patient-specific drill guides for feline sacroiliac luxation repair, and the surprising long-term outcomes of tibial tuberosity avulsion fractures, these studies challenge conventional assumptions about fixation, healing, and postoperative function.

In this episode:

✅ Arias et al. — Evaluated an undersized cementless femoral stem coated with biphasic calcium phosphate (BCP) as an alternative to traditional cemented total hip replacement. While dogs with undersized stems experienced slower early recovery and mild transient lameness, functional gait analysis demonstrated equivalent outcomes by four months postoperatively. The BCP coating promoted biological fixation through osteoconduction and osteoinduction, potentially reducing the risk of intraoperative femoral fissures associated with aggressive press-fit stem placement. 

✅ Scortea et al. — Compared 3D-printed drill guide technology with fluoroscopy-guided minimally invasive osteosynthesis (MIO) for feline sacroiliac luxation repair. Patient-specific guides achieved 92.9% adequate sacral bone purchase, compared with 64.3% for traditional MIO, while dramatically reducing cortical breaches and screw malposition. Although the guides required additional planning time and an open surgical approach, the study demonstrated substantial improvements in implant accuracy and safety. 

✅ Zweig et al. — Investigated long-term outcomes following tibial tuberosity avulsion fractures (TTAF) after skeletal maturity. Surgical fixation resulted in dramatic radiographic changes, including a 15–19° reduction in tibial plateau angle and distal patellar displacement. Despite these alterations, every surgically treated dog achieved excellent functional outcomes with no lameness or instability. In contrast, one-third of conservatively managed dogs developed severe medial patellar luxation, reinforcing the importance of maintaining extensor mechanism alignment during healing. 

Together, these studies remind us that orthopedic success is not always defined by perfect anatomy—but by achieving durable function through thoughtful planning and biologic adaptation.

🎓 Journal Articles Discussed

• Arias et al. — Kinetic and Kinematic Gait Analyses of Dogs with Undersized Cementless Stems (Biphasic Calcium Phosphate Coated) versus Cemented in Total Hip Replacement
• Scortea et al. — Comparative Analysis of 3D-Printed Drill Guides and Minimally Invasive Osteosynthesis in Feline Sacroiliac Luxation: A Cadaveric Study
• Zweig et al. — Treatment Outcome and Radiographic Appearance of Healed Tibial Tuberosity Avulsion Fractures in Skeletally Mature Dogs: 21 Cases (2016–2023) 

📚 From the November 2025 issue of VCOT

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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 issue 6, 2025, of Veterinary and Comparative Orthopedics and Traumatology, and we're exploring three studies that examine how surgical technique, technology, and long-term outcomes can shape orthopedic success. First, we'll review Arias et al., who investigate a challenging orthopedic problem and provide new data on factors influencing surgical outcome and decision making in clinical practice. The study offers practical lessons that can help refine case selection, treatment planning, and client communication. Next, we turn to Scortea et al. who compare three D printed drill guides with fluoroscopy guided minimally invasive osteosynthesis for feline sacroiliac luxation repair. This cadaveric study tackles one of the most technically demanding procedures in feline trauma surgery and asks whether patient-specific technology can improve implant accuracy and reduce the risk of screw misplacement. Finally, we'll look at Zweig et al. who evaluate the long-term radiographic appearance and functional outcomes of tibial tuberosity evulsion fractures after skeletal maturity. The findings challenge some assumptions about growth plate injury and implant placement, showing how proximal tibial morphology may change over time while clinical outcomes remain excellent. Three studies. One common theme achieving better orthopedic outcomes through precision, planning, and a deeper understanding of what happens long after the surgery is over. Let's dive in.

SPEAKER_03 2:10

So imagine you're in the OR, right? You're driving in a press fit stem for a canine total hip replacement.

SPEAKER_00 2:16

Oh, yeah. Aiming for that perfect

Arias et al. Study: Evaluating Intentionally Undersized Cementless BCP-Coated Stems vs. Standard Cemented Stems in Canine Total Hip Replacement.

SPEAKER_00 2:19

rigid stability.

SPEAKER_03 2:20

Exactly. And then suddenly you hear it. That dreaded crack of ephemeral fissure.

SPEAKER_00 2:24

Ugh. It is the absolute worst. It just instantly changes the entire trajectory of the recovery.

SPEAKER_03 2:30

It really does. Well, um, that exact scenario is what makes Arias et al. 2025 such a compelling read for today's deep dive. They actually challenge the whole conventional wisdom that maximum canal fill is the only way to get cementless stability.

SPEAKER_00 2:45

Right. They're exploring whether intentionally undersizing the stem could just, you know, eliminate that interoperative fracture risk completely.

SPEAKER_03 2:54

Yeah. So they compared a standard cemented stem against an undersized cementless stem in twelve dogs, and the undersized one was coated in biphasic calcium phosphate or BCP.

SPEAKER_00 3:04

Which is super interesting.

SPEAKER_03 3:05

It is, but I mean the immediate pushback here is biomechanical, right? We're taught that cementless stems rely entirely on immediate rigid fixation.

Kinetic Support Recovery Lag: Reviewing the 12-week force plate recovery window and early postoperative lameness linked to initial micro-instability.

SPEAKER_00 3:14

Right. They have to be tight.

SPEAKER_03 3:15

Yeah. So undersizing, it feels like um like planting a sapling in a slightly wider hole. You're relying completely on the roots to eventually anchor it over time rather than driving a post directly into tight concrete. Doesn't that initial micromotion cause immediate clinical issues?

SPEAKER_00 3:32

Aaron Ross Powell, Well, it does. And the kinetic and kinematic force plate data from the study maps that out really clearly. The dogs with the standard cemented stems, they regain normal hip extension and support by week four.

SPEAKER_03 3:44

Aaron Powell Okay. Pretty standard recovery.

SPEAKER_00 3:46

Yeah. Meanwhile, the undersized cementless group experienced a significant drop in vertical impulse and propulsion forces early on. It actually took them up to 12 weeks to show similar support recovery.

SPEAKER_03 3:57

Wow, 12 weeks. So they presented with mild early postoperative lameness.

SPEAKER_00 4:02

Exactly. Because, you know, that initial microscopic instability, it translates to subtle pain. Right. The dog's body naturally offloads weight to compensate while waiting for the biological integration to take over and stabilize the implant. Yeah. But the biology at play during that lag phase is wild. The undersized stem bridges the gap using its BCP coating.

SPEAKER_03 4:24

BCP, so that's a mixture of hydroxyapatite and beta trechalcium phosphate, right?

SPEAKER_00 4:28

You got it. And it works through osteoconduction, providing a physical microscopic scaffold for the host bone to grow into. Oh, okay. Simultaneously, the gradual dissolution of that calcium phosphate releases ions that actively stimulate osteoblast differentiation.

SPEAKER_03 4:43

Aaron Powell So that's the osteoinductive

Fissure Risk Reduction: Trading immediate biomechanical rigidity for a lower intraoperative fracture profile while managing client expectations.

SPEAKER_03 4:45

property at work. Exactly. Okay, so practically, as a surgeon, you are trading immediate biomechanical perfection for a massive reduction in fissure risk. You're banking on that biological cascade to catch up.

SPEAKER_00 4:58

Yes. And according to the clinical punchline of Arias et al. 2025, it does catch up.

SPEAKER_03 5:03

It does.

SPEAKER_00 5:04

Yeah. By the four-month mark, the kinematic data showed no significant difference in functional gait between the two groups. Both reached a regular, healthy gait pattern.

SPEAKER_03 5:12

That is huge. But wait, relying on that slower biological integration introduces a completely different vulnerability, doesn't it?

SPEAKER_00 5:19

It definitely does. When you have a cementless stem relying on a coating to stimulate osteoblasts, that bone metal interface becomes highly

Simini Protect Lavage Study: Overcoming the 42% bacterial remainder of standard saline with a 60-second antimicrobial rinse to protect the vulnerable bone-metal interface at closure.

SPEAKER_00 5:28

susceptible during those initial weeks. Right. You are setting up a literal race to the surface between those bone-building oleoblasts and opportunistic bacteria.

SPEAKER_03 5:37

Aaron Powell And if bacteria win that race and form a biofilm before the bone integrates, the entire implant is compromised.

SPEAKER_00 5:44

Exactly. Which is why surgical site management right before closure is the deciding factor in whether this undersized technique actually succeeds long term.

SPEAKER_03 5:52

Right. And we traditionally rely on standard saline lavage to clear the surgical field.

SPEAKER_00 5:57

Aaron Powell We do, but independent head-to-head studies show saline leaves 42% of bacteria behind.

SPEAKER_03 6:03

42%? Wow.

SPEAKER_00 6:04

That is an unacceptable blind spot when you are relying on delicate osteoblastic activity to secure a loose stem.

SPEAKER_03 6:11

Which is exactly why bringing SemityProtect lavage into the workflow makes so much sense structurally. It's a non-antibiotic lavage used just prior to suturing. Instead of leaving almost half the bacteria behind, simity leaves 0%. It mechanically and chemically clears out what saline misses, including resistance strains, without requiring any major changes to your existing protocol.

SPEAKER_00 6:34

And it only takes 60 seconds. For primary orthopedic procedures where biological integration is critical, going from a 42% bacterial load down to zero is the easiest risk mitigation you can perform to protect that hardware.

SPEAKER_03 6:48

Absolutely. So synthesizing the data from Arias et al. 2025, underside cementless BCP stems are a highly viable, safe alternative to cemented stems.

SPEAKER_00 6:59

Totally. Provided you manage client expectations regarding the slower initial recovery.

SPEAKER_03 7:04

Right, because the functional results equal out by month four, and you completely avoid the nightmare of intraoperative fractures. But let's leave you with a final thought to mull over before your next procedure.

SPEAKER_00 7:13

Oh, what's that?

SPEAKER_03 7:14

Well, we frame that early mild lameness as a clinical drawback. But could that temporary de-stit's comfort caused by the undersized stem actually be a hidden biological advantage?

SPEAKER_00 7:23

Wait, like acting as a natural self-imposed restriction on the dog's activity.

SPEAKER_03 7:28

Exactly. Keeping them calm and offloading the joint precisely when the bone needs quiet time to integrate.

SPEAKER_00 7:34

Huh. That is a really interesting way to look at it.

SPEAKER_03 7:37

Definitely something to think about.

SPEAKER_02 7:43

Turning the page.

Scortea et al. Study: 3D-Printed Drill Guides vs. Fluoroscopy-Guided Minimally Invasive Osteosynthesis (MIO) for Feline Sacroiliac Luxation Repair.

SPEAKER_00 7:54

Yeah, and this study aims to basically solve that exact alignment challenge, right?

SPEAKER_03 7:58

Exactly. So Scortea et al. 2025 compared traditional minimally invasive osteosynthesis, or MIO, using fluoroscopy, against a 3D printed drill guide technique. And they did this in 14 feline cadavers.

SPEAKER_00 8:10

Okay, so it's um it's kind of like comparing a highly trained pilot flying by instruments in the fog, which would be the MIO, versus laying down a physical track before the train even leaves the station. That's the 3D DGT.

SPEAKER_03 8:20

That is a great analogy, yeah.

SPEAKER_00 8:22

But wait, doesn't placing that custom track require a much bigger surgical approach? Like you can't just slip that guide through a tiny incision.

SPEAKER_03 8:30

No, you really can't. That's the main catch here. The 3D printed guide technique actually requires a standard open reduction and frankly, extensive soft tissue dissection.

SPEAKER_00 8:41

Wow. Okay, because you need it to fit perfectly against the bone, right? Trevor Burrus, Jr.

SPEAKER_03 8:44

Right. You need to achieve this perfect press fit of the guide onto the sacral wing.

SPEAKER_00 8:48

Right.

SPEAKER_03 8:49

And it also demands way more preoperative prep.

SPEAKER_00 8:51

Aaron Powell How much more prep are we talking about here?

SPEAKER_03 8:53

Aaron Powell It's a median of about 34 minutes for planning and printing compared to just eight and a half minutes for MIO.

SPEAKER_00 8:59

Aaron Powell So you're adding an extra 25 minutes of prep and a much larger open incision. Does that actually translate to you know safer, more reliable surgeries for the patient?

SPEAKER_03 9:09

It really does. I mean the quantitative

Sacral Bone Purchase Efficacy: How 3D printed guides hit the critical >60% stability threshold 93% of the time, compared to just 64% using MIO.

SPEAKER_03 9:11

highlights are striking. The 3D DDT resulted in far fewer suboptimal placements. We're talking only 7.14%.

SPEAKER_00 9:19

Aaron Powell Compared to what for the MIO group?

SPEAKER_03 9:21

Aaron Powell Compared to 42.85% for MIO.

SPEAKER_00 9:24

Trevor Burrus Wait, 42%? That is uh that's incredibly high for a minimally invasive standard.

SPEAKER_03 9:29

Aaron Powell It is high, yeah. And to ensure mechanical stability, a screw actually needs greater than 60 percent sacral bone purchase.

SPEAKER_00 9:37

Okay, so how did the two methods compare on that specific stability metric?

SPEAKER_03 9:41

Aaron Powell The 3D guides achieved that critical threshold almost 93% of the time, whereas MIO only hit it around 64 percent.

SPEAKER_00 9:49

Aaron Powell That's a massive difference. Aaron Powell And what about cortical breaches? Because I imagine blindly driving a screw uh even with fluoro has some serious risks.

SPEAKER_03 9:58

Aaron Powell Exactly. MIO actually resulted in five drill exit point breaches. And one of those went straight dorsally into the sacral canal.

SPEAKER_00 10:06

Oh wow. Straight into the canal. That's literally a nightmare scenario.

SPEAKER_03 10:09

Aaron Powell Right. But with the 3D DTT, there was only one ventral breach in total. It also significantly reduced entry point translation on the dorso ventral axis.

SPEAKER_00 10:18

Trevor Burrus, Jr.

SPEAKER_03 10:18

Like how much of a reduction are we talking about down to 0.42 millimeters for the 3D guide versus 1.64 millimeters for MIO.

SPEAKER_00 10:26

That's incredible precision. So what's the big takeaway here?

SPEAKER_03 10:29

Aaron Powell Here is what a small animal surgeon should remember Scrtea et al. 2025 shows that 3D printed guides drastically reduce cortical breaches and improve bone purchase in feline sacrums compared to MIO?

SPEAKER_00 10:43

So you're basically trading a larger incision for a massive upgrade in mechanical accuracy and safety.

SPEAKER_03 10:49

Exactly. It's a trade-off, but one that really pays off mechanically.

SPEAKER_00 10:52

It's just wild to think about. I mean, as 3D printing tech gets, you know, faster and cheaper to use right in the clinic, will custom interoperative guides eventually render freehand or fluoroscopy guided MIO completely obsolete for these high-stakes

Zweig et al. Study: Long-Term Radiographic Appearance and Functional Outcomes of Tibial Tuberosity Avulsion Fractures (TTAF) After Skeletal Maturity.

SPEAKER_00 11:06

pelvic repairs?

SPEAKER_03 11:07

It's definitely a compelling question.

SPEAKER_00 11:08

Right. Definitely something to think about before your next scrub in. Full article links are in the show notes.

SPEAKER_02 11:14

Continuing with the next published study.

SPEAKER_03 11:18

So when you really look to the anatomy of a growing puppy, fixing a tibial tuberosity, a vulsion fracture, or TTAF, it feels completely counterintuitive.

SPEAKER_00 11:28

Oh, absolutely. I mean, you've got a four-month-old pup on the table, and you're essentially driving pins straight across a growing physicist.

SPEAKER_03 11:34

Right. It's it's a lot like nailing down a sliding door. You'd intuitively expect that to just, you know, completely derail the joint's developmental track.

SPEAKER_00 11:41

Aaron Powell, Jr. You really would. But today, we're doing a deep dive to extract the clinical punchline from a 2025 retrospective study, Zweg et al.

SPEAKER_03 11:51

Yeah, we want to see exactly how this treatment impacts stifle joints at skeletal maturity. And more importantly, what you should actually be doing differently in the OR tomorrow.

SPEAKER_00 12:00

Exactly. So to see if that intuition holds up, Zweeg et al. 2025 tracked 21 dogs that had been treated for TTFs into adulthood.

SPEAKER_03 12:07

Aaron Powell Okay. And they they looked at bilateral stifle radiographs. Right. Like once the dogs reach skeletal maturity.

SPEAKER_00 12:13

Yeah, they compared those managed surgically

Postoperative Morphological Warping: Detailing the massive 15 to 19-degree postoperative drop in TPA and distal patellar shifts caused by growth plate pinning into adulthood.

SPEAKER_00 12:16

so, either with pins only, or a pin intention band against those managed conservatively in a cast.

SPEAKER_03 12:21

Aaron Powell I mean, if we're tethering an apophysis that's meant to be dynamic, you expect some deformity. Like rigid implants across that growth plate have to severely restrict tibial expansion.

SPEAKER_00 12:31

Oh, it restricts it radically. The radiographic findings showed that in the surgically managed dogs, the tibial plateau angle, the TPA dropped by an incredible 15 to 19 degrees.

SPEAKER_03 12:44

Wait, really? A 15 to 19 degree drop?

SPEAKER_00 12:46

Yeah, compared to their normal uninjured stifles. And because that apophysis was tethered, the patella shifted distally as well.

SPEAKER_03 12:54

Aaron Ross Powell That is a massive biomechanical shift. Normal is what typically in the mid-20s. So these adult dogs were walking around with a TPA of maybe four to ten degrees.

SPEAKER_00 13:04

Exactly. It's a huge anatomical change.

SPEAKER_03 13:05

Aaron Powell With that kind of morphological warping, the stifle mechanics should be severely compromised. I'd expect, you know, significant lameness or or joint instability.

SPEAKER_00 13:14

Aaron Powell Well, that is the clinical paradox at the heart of this study. Despite that drastic anatomical shift, every single surgically managed dog had an excellent clinical outcome.

SPEAKER_03 13:23

Aaron Powell Really? No lameness at all.

SPEAKER_00 13:25

A lameness score of zero. No stifle instability whatsoever. And crucially for the surgeons listening, they achieved these outcomes even with the surgical implants left in situ well past skeletal maturity.

SPEAKER_03 13:38

Aaron Powell Wow. So the body just it adapts to the flattened plateau and the distally shifted patella without any functional deficit?

SPEAKER_00 13:45

It seems so, yeah.

SPEAKER_03 13:46

So if the cervical group did that well despite the anatomical distortion, I'm assuming the cast managed dogs, whose physis

Conservative Cast Management Pitfalls: Reviewing the severe grade III or IV medial patellar luxation complication that developed in a third (2 out of 6) of the untethered cast cohort.

SPEAKER_03 13:53

was left completely unrestricted, maintained perfect geometry.

SPEAKER_00 13:57

Aaron Powell Well, they did maintain their normal TPA anatomy, but and this is a major complication, while their plateau angles were perfectly preserved, two out of the six dogs managed in a cast developed severe grade three or four medial patellar luxation.

SPEAKER_03 14:13

Wait. A third of the cast managed dogs develop severe patellar luxation just from conservative management.

SPEAKER_00 14:18

Yep. Two out of six.

SPEAKER_03 14:20

That suggests that the untethered evulsion fragment is causing a cascading failure up the limb, right?

SPEAKER_00 14:25

Precisely. We really have to look at the biomechanics of why that happens because when you leave that fracture in a cast, the fracture

Extensor Axis Displacement: How the continuous proximal pull of the quadriceps shifts unanchored healing fragments to derail the entire mechanical axis.

SPEAKER_00 14:32

site isn't rigidly stabilized.

SPEAKER_03 14:34

Right. So it's still shifting around.

SPEAKER_00 14:35

Exactly. The powerful pull of the quadriceps mechanism continuously acts on that untethered evulsion fragment, which displaces it proximally as it heals.

SPEAKER_03 14:45

Aaron Powell Oh, that makes perfect sense. It's like um moving the anchor point of a loaded bowstring.

SPEAKER_00 14:51

That's a great way to put it.

SPEAKER_03 14:52

Yeah, like if the tibule tuberosity shifts proximally and medially during healing, you're fundamentally altering the mechanical axis of the entire extensor mechanism.

SPEAKER_00 15:01

Right. The quadriceps pull is no longer aligned with the trochlear groove, so the patella just it pops right out.

SPEAKER_03 15:07

You completely lose that vital alignment.

SPEAKER_00 15:09

You do. So for the small animal surgeons scrubbing in tomorrow, the clinical punchline from Zweig et al. 2025 is very clear. Surgical management remains the gold standard, regardless of the significant TPA shifts it causes.

SPEAKER_03 15:22

Because the stifle joint clearly tolerates and adapts to the altered TPA and patellar position.

SPEAKER_00 15:28

Exactly. But it absolutely does not tolerate an unanchored extensor mechanism.

SPEAKER_03 15:33

Right. Which means if an owner insists on conservative casting, maybe due to financial constraints or fear of surgery, you cannot treat it as a benign alternative.

SPEAKER_00 15:43

No, you have to directly counsel them on the high biomechanical risk of medial patellar laxation.

SPEAKER_03 15:48

Aaron Powell Yeah. You're basically trading a functional joint with a weird angle for a joint with perfect angles that doesn't actually work.

SPEAKER_00 15:55

Aaron Powell That is the perfect way to frame it. Clinical function doesn't always obey perfect geometry, you know? The body can compensate for a flattened plateau, but it just cannot compensate for a displaced quadriceps anchor.

SPEAKER_03 16:08

That's yeah, that's fascinating. But before we wrap up this deep dive, there is a really interesting biomechanical theory to mull over during your next scrub-in.

SPEAKER_00 16:16

Oh, right, the cruciate theory.

SPEAKER_03 16:17

Yeah. So we know from biomechanical models that a significantly decreased TPA actually reduces strain on the cranial cruciate ligament. So if surgically fixing this fracture drops the TPA by 15 degrees, could leaving these implants in place actually act as a protective measure against future cruciate ligament disease?

SPEAKER_00 16:37

I mean, it's an incredible thought. We might literally be looking at a prophylactic side effect of a puppy fracture repair.

SPEAKER_03 16:44

Right.

SPEAKER_00 16:44

It raises fantastic questions for future long-term cruciate tracking.

SPEAKER_03 16:49

Definitely something to think about the next time you're placing those pens. Anyway, remember, full article links for Zwag et al. Catch you on the next deep dive.

SPEAKER_02 17:05

That's it for this episode of the Simony Small Animal Surgery Podcast. This show is brought to you by Simony 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.