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Muroi et al: A Retrospective Study of Risk Factors Associated with Refracture after Repair of Radial–Ulnar Fractures in Small-Breed Dogs
Veterinary and Comparative Orthopaedics and Traumatology 2, 2025

🔍 Key Findings

  • Refracture occurred in 5.5% of limbs, with higher incidence in the plate removal group (12.5%) vs. non-removal (3.5%).
  • In the non-plate removal group, refractures occurred at the most distal screw site, linked to greater screw position change during growth (OR 1.79, p=0.04).
  • Screw-to-bone diameter ratio (SBDR) >0.4 was a significant risk factor for refracture in the plate retention group.
  • In the plate removal group, refractures occurred at the original fracture site, associated with lower pixel value ratio (bone mineral density) and reduced radial thickness.
  • Implant-induced osteoporosis (IIO) beneath the plate likely contributed to refracture risk after plate removal.
  • Younger age at fracture (<6 months) was associated with higher refracture risk due to ongoing radial growth and shifting screw position.
  • No significant association was found between refracture and plate type (locking vs conventional), fixation method, or ulnar union.
  • Recommendations include careful SBDR sizing, motion restriction, and cautious plate removal decisions in growing dogs.

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← Articles

Muroi et al: A Retrospective Study of Risk Factors Associated with Refracture after Repair of Radial–Ulnar Fractures in Small-Breed Dogs
Veterinary and Comparative Orthopaedics and Traumatology 2, 2025

🔍 Key Findings

  • Refracture occurred in 5.5% of limbs, with higher incidence in the plate removal group (12.5%) vs. non-removal (3.5%).
  • In the non-plate removal group, refractures occurred at the most distal screw site, linked to greater screw position change during growth (OR 1.79, p=0.04).
  • Screw-to-bone diameter ratio (SBDR) >0.4 was a significant risk factor for refracture in the plate retention group.
  • In the plate removal group, refractures occurred at the original fracture site, associated with lower pixel value ratio (bone mineral density) and reduced radial thickness.
  • Implant-induced osteoporosis (IIO) beneath the plate likely contributed to refracture risk after plate removal.
  • Younger age at fracture (<6 months) was associated with higher refracture risk due to ongoing radial growth and shifting screw position.
  • No significant association was found between refracture and plate type (locking vs conventional), fixation method, or ulnar union.
  • Recommendations include careful SBDR sizing, motion restriction, and cautious plate removal decisions in growing dogs.

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Multiple Choice Questions on this study

In Muroi 2025 et al., on refracture risk, what was the overall refracture rate in the study population of small-breed dogs?

A. 2.0%
B. 5.5%
C. 8.2%
D. 12.5%
E. 15.0%

Answer: 5.5%

Explanation: 10 of 181 limbs developed refracture, yielding an overall refracture rate of 5.5%.
In Muroi 2025 et al., on refracture risk, what screw-to-bone diameter ratio (SBDR) is suggested as a **threshold** for increased refracture risk in growing dogs?

A. >0.2
B. >0.3
C. >0.4
D. >0.5
E. >0.6

Answer: >0.4

Explanation: An SBDR over 0.4 may weaken bone, especially when screws become relatively large due to growth.
In Muroi 2025 et al., on refracture risk, all refractures in the **plate removal group** occurred at which location?

A. Proximal screw hole
B. Most distal screw hole
C. Ulnar metaphysis
D. Same site as initial fracture
E. Above the plate tip

Answer: Same site as initial fracture

Explanation: Refractures after plate removal occurred at the same site as the original fracture, linked to decreased BMD and thickness.
In Muroi 2025 et al., on refracture risk, what factor was significantly associated with refracture in dogs **retaining plates**?

A. Plate type (locking vs. conventional)
B. Screw torque at insertion
C. Amount of position change of the most distal screw
D. Proximal fracture location
E. Bridging vs compression method

Answer: Amount of position change of the most distal screw

Explanation: In the non-removal group, greater positional change of the distal screw (OR 1.79, p=0.04) was linked to refracture.
In Muroi 2025 et al., on refracture risk, what bone quality indicator was significantly lower in dogs that refractured **after plate removal**?

A. Callus volume
B. Radial width index
C. Pixel value ratio (PVR)
D. Haversian canal diameter
E. Trabecular density

Answer: Pixel value ratio (PVR)

Explanation: Lower PVR was significantly associated with refracture risk after plate removal, suggesting reduced bone mineral density.

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