In Silico Analysis of Stress Distribution in Proximal Interphalangeal Joint Arthrodesis in Horses Using a Locking Compression Plate

This study aimed to compare the stress distribution in proximal interphalangeal joint arthrodesis with locking compression plate in horses based on the type and method of screw implantation in the proximal hole and partial or total removal of implants after fusion.Finite element analysis.Proximal interphalangeal joint arthrodesis was simulated using a 3-hole, 4.5-mm narrow locking compression plate combined with two 5.5-mm transarticular screws. Models were created according to the type (cortex or locking) and method of implantation (uni- or bicortical) of the screw in the proximal hole of the locking compression plate. Four conditions were simulated: Immediate postoperative, ankylosis, ankylosis with partial removal (transarticular screws remaining) and ankylosis with no implants. An axial load of 8,700 N was applied, and the major principal stresses in the bones and von Mises stress in the implants were evaluated.Cortical screws in the proximal hole better distributed the stresses, reducing their concentration along the diaphysis of the proximal phalanx in the postoperative condition. Stress distribution did not differ between partial and total implant removal. High stresses were observed in the implants, especially when locking screws were used, with a reduction observed after ankylosis simulation.A cortex screw in the proximal hole reduces stress concentration in the proximal phalanx. Retaining the transarticular screws after ankylosis did not alter the stress pattern in the bone.