Experimental evaluation of cortical screw placement in lag fashion into the distal phalanx in standing horses.

The objectives of this in vivo experimental study were to evaluate the feasibility of cortical screw insertion into the intact distal phalanx in standing sedated horses and to document potential postoperative complications. One cortical screw was randomly inserted in lag fashion into each distal phalanx in 9 horses. The second surgery on the contralateral limbs was performed 2-3 weeks after the first operation, when a 4.5-mm cortical screw was inserted in lag fashion into the distal phalanx of sedated horses following perineural analgesia. Following surgery, the drill hole was filled with an antibiotic-soaked swab, which was changed every 48 h. The horses were euthanised 8 weeks after the second surgery. The hooves were disarticulated and evaluated macroscopically and by computed tomography. The surgery time was 13.9 ± 4.8 min (mean ± SD). Pain scores and lameness gradually decreased after 7 days. Solar canal penetration (SCP) was detected in 10 out of the 18 distal phalanges (55.5%). In 7 out of the 10 penetrations intraoperative bleeding was obvious. No postoperative infection was observed. Screw insertion into the distal phalanx was easily and quickly accomplished in standing horses, but its advantages in horses with sagittal fractures should be investigated further. SCP had no impact on postoperative lameness.