Double J-shaped Kirschner wire fixation provides superior biomechanical stability for feline sacroiliac luxation compared with conventional techniques

Abstract

Objective: To compare the biomechanical stability of 3 fixation techniques for unilateral sacroiliac (SI) luxation using 3-D-printed feline pelvic models.

Methods: Eighteen 3-D-printed pelvic models were generated from CT data of a 6.6-kg cat. The study was conducted from July 25 through September 10, 2025. A right SI luxation with ipsilateral pubic and ischial osteotomies was created, and models were fabricated for 3 fixation configurations (n = 6/group): single lag screw with transiliac pinning (SP), double parallel Kirschner wires (DK), and double J-shaped Kirschner wires (DJ). A 3-D-printed femur was toggle pinned to the acetabulum to reproduce stance. Axial compression was applied to the femoral head at 5 mm/min to 15° pelvic rotation. Outcomes included rotational stiffness (primary), maximum load at 10° rotation, and energy absorption.

Results: DJ constructs showed approximately 3-fold greater initial rotational stiffness and higher energy absorption than SP and DK. Mean maximum load to 10° rotation was 93.10 N for DJ versus 33.32 N (SP) and 36.59 N (DK). No differences were detected between SP and DK for any parameter.

Conclusions: In this ex vivo 3-D-printed model, DJ fixation provided superior rotational stability compared with SP and DK techniques.

Clinical relevance: The DJ technique may offer a biomechanically robust alternative for stabilizing feline SI luxation. By avoiding the narrow sacral safe corridor required for lag screw placement, this method may reduce the risk of iatrogenic nerve injury while preserving sacral bone integrity to ensure optimal purchase and minimize the risk of fixation failure during stabilization.

Keywords: 3-D–printed pelvic model; J-shaped K-wire fixation; feline biomechanics; rotational stability; sacroiliac luxation.