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Kershaw et al: Patient-specific Guides Improve the Accuracy and Safety of Transcondylar Screw Placement—A Cadaveric Study in the Canine Humerus
Veterinary and Comparative Orthopaedics and Traumatology 5, 2025

🔍 Key Findings

  • 3D-printed patient-specific guides (PSGs) significantly improved accuracy of drill hole entry (p < 0.001) and exit (p = 0.044) compared to commercial aiming devices (AD).
  • Zero joint penetrations occurred with PSGs, whereas 3 of 7 AD-guided screws were predicted to penetrate the joint (p = 0.19).
  • Variance in exit point and drill angle was significantly lower in PSG group, suggesting more consistent results.
  • One PSG case failed due to improper guide seating, but this was corrected with improved soft tissue clearance.
  • PSGs enabled safer trajectories despite use by novice surgeons, emphasizing their value in less experienced hands.
  • Drill holes placed with ADs deviated more cranially and distally, increasing the risk of articular violation.
  • Use of PSGs allowed for tighter clustering of drill trajectories, especially in the cranial–caudal axis.
  • Subjective feedback favored PSGs for ease of use and ergonomic design, despite requiring slightly larger incisions.

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← Articles

Kershaw et al: Patient-specific Guides Improve the Accuracy and Safety of Transcondylar Screw Placement—A Cadaveric Study in the Canine Humerus
Veterinary and Comparative Orthopaedics and Traumatology 5, 2025

🔍 Key Findings

  • 3D-printed patient-specific guides (PSGs) significantly improved accuracy of drill hole entry (p < 0.001) and exit (p = 0.044) compared to commercial aiming devices (AD).
  • Zero joint penetrations occurred with PSGs, whereas 3 of 7 AD-guided screws were predicted to penetrate the joint (p = 0.19).
  • Variance in exit point and drill angle was significantly lower in PSG group, suggesting more consistent results.
  • One PSG case failed due to improper guide seating, but this was corrected with improved soft tissue clearance.
  • PSGs enabled safer trajectories despite use by novice surgeons, emphasizing their value in less experienced hands.
  • Drill holes placed with ADs deviated more cranially and distally, increasing the risk of articular violation.
  • Use of PSGs allowed for tighter clustering of drill trajectories, especially in the cranial–caudal axis.
  • Subjective feedback favored PSGs for ease of use and ergonomic design, despite requiring slightly larger incisions.

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Multiple Choice Questions on this study

In Kershaw 2025 et al., on PSG vs AD, which surgeon experience level was used to assess PSG utility?

A. Board-certified orthopedist
B. Intern-level surgeon
C. Specialist in training
D. Novice/nonspecialist surgeon
E. Resident surgeon

Answer: Novice/nonspecialist surgeon

Explanation: The study aimed to assess PSG utility in less experienced hands; all procedures were performed by a novice surgeon.
In Kershaw 2025 et al., on PSG vs AD, how many joint penetrations occurred in the PSG group during cadaveric screw placement?

A. 0
B. 1
C. 2
D. 3
E. 4

Answer: 0

Explanation: All 7 PSG placements avoided joint penetration, compared to 3/7 joint penetrations in the AD group.
In Kershaw 2025 et al., on PSG vs AD, what factor contributed to an outlier error in the PSG group?

A. Drill bit breakage
B. CT model error
C. Incomplete guide seating due to soft tissue
D. Intraoperative fluoroscopy malfunction
E. Guide design flaw

Answer: Incomplete guide seating due to soft tissue

Explanation: Soft tissue under the guide prevented proper seating, affecting trajectory until revised.
In Kershaw 2025 et al., on PSG vs AD, what was the most significant benefit of using a patient-specific guide (PSG) during transcondylar screw (TCS) placement in dogs?

A. Reduced operative time
B. Improved cosmetic outcome
C. Elimination of articular cartilage wear
D. Significantly improved entry and exit hole accuracy
E. Decreased need for intraoperative fluoroscopy

Answer: Significantly improved entry and exit hole accuracy

Explanation: PSGs significantly improved drill hole entry (p < 0.001) and exit (p = 0.044) accuracy over aiming devices.
In Kershaw 2025 et al., on PSG vs AD, which directional deviation was more common in screws placed using the aiming device?

A. Caudal and proximal
B. Caudal and distal
C. Cranial and proximal
D. Cranial and distal
E. Neutral

Answer: Cranial and distal

Explanation: Screws placed with ADs deviated more cranially and distally than those placed with PSGs.

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