Evaluation of a Novel Screw Position in a Type III Distal Phalanx Fracture Model: An Ex Vivo Study.
Authors: Bindler Dorian, Koch Christoph, Gendron Karine, Ferguson Stephen J, Kaposi Andras D, Papp Miklos, Bodó Gábor
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Novel Screw Positioning for Type III Distal Phalanx Fractures Type III distal phalanx fractures require robust internal fixation to promote healing, yet conventional screw placement must balance mechanical strength with the anatomical constraints of the solar canal. Bindler and colleagues compared two cortical screw lag techniques using 24 disarticulated equine hooves and isolated distal phalanges, subjecting sagittal-plane fracture models to three-point bending tests whilst assessing solar canal penetration via CT and macroscopic examination. The novel more palmar/plantar screw position—positioned perpendicular to the conventional midpoint location—demonstrated significantly superior biomechanical properties: 31% greater load to failure and 41% increased bending stiffness in isolated bones, with correspondingly longer screw lengths achievable. However, this mechanical advantage came at a cost; 13 of 52 specimens showed solar canal lumen reduction, with nine occurring in forelimbs where the anatomical geometry favoured deeper penetration. For practitioners, whilst the palmar/plantar position offers enhanced construct rigidity that may accelerate fracture consolidation, the increased risk of solar canal compromise—potentially leading to ischaemic necrosis and chronic pain—warrants careful case selection and precise imaging guidance before adoption in clinical practice.
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Practical Takeaways
- •The novel distal screw position provides superior mechanical fixation strength for type III distal phalanx fractures, potentially improving healing outcomes
- •However, this technique carries a notably higher risk of penetrating the solar canal (especially in forelimbs), which could lead to infection and complications—careful anatomical consideration is essential if adopting this approach
- •Conventional screw placement remains safer regarding solar canal integrity; surgeons must weigh mechanical advantages against the risk of solar canal compromise when selecting screw position
Key Findings
- •Novel distal screw positioning increased bending stiffness by 41% and maximum load at failure by 31% compared to conventional placement
- •Group 2 (distal positioning) allowed significantly longer screws, particularly in forelimbs
- •Solar canal penetration occurred in 25% of specimens (13/52), exclusively in group 2, with 69% of these cases in forelimbs