Proximal interphalangeal joint arthrodesis in the horse

This retrospective case study evaluated proximal interphalangeal joint arthrodesis in 32 horses referred to the Clinic for Equine Surgery, Vetsuisse Faculty, University of Zurich, between 1995 and 2018. The study had three objectives. The first was to evaluate the success rate of four different surgical techniques for arthrodesis to determine the surgical method with the best prognosis based on in-house experience. The second was to test the hypothesis that the prognosis for proximal interphalangeal joint arthrodesis has improved since the introduction of an equine locking compression plate for the proximal interphalangeal joint (PIP-LCP). The third objective was to evaluate the success rate of a pentagonal plate used in a pilot project from 2004 to 2006. The long-term outcomes were determined by telephone interview. The results were presented using descriptive statistics. A total of 18 horses (56 %) had osteoarthritis of the proximal interphalangeal joint, ten (31 %) had traumatic luxation of the proximal interphalangeal joint and three (10 %) had bone cysts. The indication for arthrodesis could not be determined from the history in the remaining horse. A PIP-LCP and additional transarticular lag screws were used in 13 horses (41 %) and a dynamic compression plate (DCP) with additional transarticular lag screws was used in 13 other horses (41 %). A double-plate technique using two abaxially placed DCPs and an additional transarticular lag screw was used in one horse, and a novel pentagonal plate was used in the remaining 5 horses. Both forelimbs were operated in two horses. The total success rate in terms of soundness at the walk and trot/return to the previous performance level was 22 of 32 (70 %). The PIP-LCP technique was successful in 11 of 13 (83 %) and the DCP technique in 9 of 13 cases (70 %). Of the four horses treated with the pentagonal plate that had sufficient follow-up information, three had to be euthanized; one of the three horses had implant failure, one had implant failure and infection in the same limb and one had implant failure and infection in two different limbs. Ten of the 32 horses (31 %) developed an infection, which was associated with the implant in seven horses, seven other horses (22 %) had implant failure, three (9 %) developed laminitis and one (3 %) suffered a fracture of the second phalanx. All horses with bone cysts, eight of ten horses (80 %) with traumatic luxation and 11 of 18 horses (60 %) with osteoarthritis had a go