Bindler, Dorian; Koch, Christoph; Gendron, Karine; Ferguson, Stephen John; Kaposi, Andras D.; Papp, Miklos; Bodó, Gabor (2015). Evaluation of a Novel Screw Position in a Type III Distal Phalanx Fracture Model: An Ex Vivo Study. Veterinary surgery, 44(7), pp. 829-837. Wiley-Blackwell 10.1111/vsu.12354
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OBJECTIVE:
Mechanical evaluation of a novel screw position used for repair in a type III distal phalanx fracture model and assessment of solar canal penetration (SCP).
STUDY DESIGN:
Experimental study.
SAMPLE POPULATION:
Disarticulated equine hooves (n = 24) and 24 isolated distal phalanges.
METHODS:
Hooves/distal phalanges cut in a sagittal plane were repaired with 1 of 2 different cortical screw placements in lag fashion. In group 1 (conventional screw placement), the screw was inserted halfway between the proximal border of the solar canal (SC) and the subchondral bone surface on a line parallel to the dorsal cortex, whereas in group 2, the screw was inserted more palmar/plantar, where a perpendicular line drawn from the group 1 position reached the palmar/plantar cortex. Construct strength was evaluated by 3-point bending to failure. SCP was assessed by CT imaging and macroscopically.
RESULTS:
Screws were significantly longer in group 2 and in forelimbs. Group 2 isolated distal phalanges had a significantly more rigid fixation compared with the conventional screw position (maximum point at failure 31%, bending stiffness 41% higher). Lumen reduction of the SC was observed in 13/52 specimens (all from group 2), of which 9 were forelimbs.
CONCLUSIONS:
More distal screw positioning compared with the conventionally recommended screw position for internal fixation of type III distal phalangeal fractures allows placement of a longer screw and renders a more rigid fracture fixation. The novel screw position, however, carries a higher risk of SCP