Biomechanical comparison of triangular osteosynthesis and triangular minimally invasive spinopelvic stabilization technique for pelvic fragility fractures.

Abstract

To biomechanically compare triangular osteosynthesis (TOS) and a minimally invasive triangular spinopelvic stabilization (TMSS) technique for Type IV fragility fractures of the pelvis (FFP) in a cadaveric model. Six fresh-frozen lumbopelvic specimens (L3-pelvis; mean age 61.5 ± 11.5 yrs) with simulated Type IV U-shaped sacral fractures were sequentially instrumented with TOS (bilateral iliosacral screws + lumbopelvic fixation) and TMSS (bilateral iliac screws with transverse connecting rod + lumbopelvic fixation). Constructs were cyclically loaded (200-430 N; 25,000 cycles or 1 cm axial displacement) to simulate postoperative single-leg stance loading. Fracture displacement was quantified using a motion capture system. All but one TOS specimen completed 25,000 cycles. Bone mineral density had no effect on displacement. TMSS showed lower maximum fracture displacement (6.05 mm) than TOS (12.12 mm; p= 0.071). Displacement after 1000 cycles averaged 56% (TOS) and 62% (TMSS) of the maximum. TMSS provided comparable or improved stability versus TOS and, with its minimally invasive design, may offer a viable alternative for FFP Type IV treatment. Further clinical validation is warranted.