← Articles

Welsh et al: Biomechanical comparison of one pin versus two pin fixation in a canine tibial tuberosity avulsion fracture model
Veterinary Surgery 5, 2023

🔍 Key Findings

  • Two-pin fixation had significantly greater strength (639 N) than single-pin fixation (426 N) in TTAF models (p = .003).
  • Stiffness was also higher with two-pin constructs (72 N/mm vs 57 N/mm); statistically significant (p = .029).
  • Both fixation types withstood loads greater than quadriceps force in dogs at a walk (240 N), indicating clinical viability.
  • Failure was most commonly due to pin bending or pullout (82%), with fewer cases of ligament tearing or epiphyseal fracture.
  • K-wire insertion angle (KWIA) did not significantly differ between fixation types (p = .13).
  • Single larger pins delivered ~68% of the strength and ~83% of the stiffness of two smaller vertically aligned pins.
  • Clinical implication: Two vertically aligned pins are biomechanically superior for TTAF fixation in canine models.
  • Study used mature cadavers, which may underestimate loads and stiffness compared to immature clinical cases.

Simini Surgery Review Podcast

How critical is this paper for crushing the Boards?

🚨 Must-know. I’d bet on seeing this.

📚 Useful background, not must-know.

💤 Skip it. Doubt it’ll ever show up.

Thanks for the feedback!
‍We'll keep fine-tuning the articles vault.
Oops — didn’t go through.
‍Mind trying that again?
← Articles

Welsh et al: Biomechanical comparison of one pin versus two pin fixation in a canine tibial tuberosity avulsion fracture model
Veterinary Surgery 5, 2023

🔍 Key Findings

  • Two-pin fixation had significantly greater strength (639 N) than single-pin fixation (426 N) in TTAF models (p = .003).
  • Stiffness was also higher with two-pin constructs (72 N/mm vs 57 N/mm); statistically significant (p = .029).
  • Both fixation types withstood loads greater than quadriceps force in dogs at a walk (240 N), indicating clinical viability.
  • Failure was most commonly due to pin bending or pullout (82%), with fewer cases of ligament tearing or epiphyseal fracture.
  • K-wire insertion angle (KWIA) did not significantly differ between fixation types (p = .13).
  • Single larger pins delivered ~68% of the strength and ~83% of the stiffness of two smaller vertically aligned pins.
  • Clinical implication: Two vertically aligned pins are biomechanically superior for TTAF fixation in canine models.
  • Study used mature cadavers, which may underestimate loads and stiffness compared to immature clinical cases.

Simini Surgery Review Podcast

Know What Matters in the Literature - and Why

We distill peer-reviewed surgical studies into clinically relevant summaries and
exam-style questions, so you can make informed decisions with confidence.

Free Access. No Spam. Just Smarter Surgical Learning

Multiple Choice Questions on this study

In Welsh 2023 et al., on TTAF fixation methods, which failure mode was **most common** in both groups during mechanical testing?

A. Patellar ligament rupture
B. Implant infection
C. Epiphyseal fracture
D. Pin bending and pullout
E. Physeal closure

Answer: Pin bending and pullout

Explanation: 82% of failures were due to pin bending and pullout in both fixation groups.
In Welsh 2023 et al., on TTAF fixation methods, what was the estimated quadriceps force at a walk used as a benchmark for load testing?

A. 150 N
B. 200 N
C. 240 N
D. 300 N
E. 400 N

Answer: 240 N

Explanation: 240 N was cited as the estimated quadriceps force during walking, used to benchmark construct strength.
In Welsh 2023 et al., on TTAF fixation methods, which of the following variables did **not significantly differ** between single- and two-pin constructs?

A. Construct stiffness
B. Construct strength
C. Kirschner wire insertion angle (KWIA)
D. Load to failure
E. Normalized stiffness

Answer: Kirschner wire insertion angle (KWIA)

Explanation: The KWIA values were not statistically different between groups (p = .13).
In Welsh 2023 et al., on TTAF fixation methods, what was the primary mechanical benefit of two-pin fixation over single-pin fixation?

A. Greater pin insertion angle
B. Lower KWIA variance
C. Improved stiffness and strength
D. Reduced surgical time
E. Lower implant migration

Answer: Improved stiffness and strength

Explanation: Two-pin fixation had significantly greater stiffness (72 N/mm) and strength (639 N) than single-pin fixation (57 N/mm and 426 N).
In Welsh 2023 et al., on TTAF fixation methods, what approximate % of the **strength** did the single-pin construct achieve compared to two-pin fixation?

A. 45%
B. 59%
C. 68%
D. 82%
E. 96%

Answer: 68%

Explanation: Single-pin constructs had a mean strength that was 68% of that provided by two-pin fixation.

Access the full library of surgical summaries and exam-style questions.

Get Instant Access

Educational content developed independently and supported by Simini.

The maker of Simini Protect Lavage.

Review More Key Summaries from this Veterinary Surgery Journal Issue

Lampart

 et al: 

Evaluation of the accuracy and intra‐ and interobserver reliability of three manual laxity tests for canine cranial cruciate ligament rupture—An ex vivo kinetic and kinematic study

Hertel

 et al: 

Successful venotomy for portal tumor thrombus removal due to pancreatic carcinoma in a dog

Monnet

 et al: 

Influence of conventional versus unidirectional barbed suture on leakage pressures in canine vesicourethral anastomosis: An ex-vivo study

Mullins

 et al: 

Accuracy of pin placement in the canine thoracolumbar spine using a free-hand probing technique versus 3D-printed patient-specific drill guides: An ex-vivo study

Fracka

 et al: 

3D-printed, patient-specific cutting guides improve femoral and tibial cut alignment in canine total knee replacement