Abstract
Objective
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.
Study Design
Finite element analysis.
Methods
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.
Results
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.
Conclusion
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.
Keywords
equine - proximal interphalangeal joint - ankylosis - finite element analysis - locking
compression plate
