Two-hour ex vivo biomechanical evaluation of glass polyalkenoate cement-augmented sternal fixation in sheep.

BACKGROUND

Adhesive augmented sternal fixation (AASF) using glass polyalkenoate cements (GPC) may improve sternal stability after median sternotomy, but construct-level performance within the first 24 h post-application remains poorly characterized. This study evaluated whether AASF using a proprietary GPC formulation improved mechanical stability at 2 h post-application in an ovine model.

METHODS

Twelve excised Merino cross sheep sternums were assigned to wired-only or AASF groups (n = 6/group). Median sternotomies were performed and sterna were closed according to treatment allocation. Specimens were tested 2 h post-application under cyclic lateral distraction loading. Peak load began at 100 N and increased every 30 cycles to a maximum of 500 N, for 150 total cycles. Displacement was measured using a transducer spanning the transection line.

FINDINGS: Both fixation groups exhibited similar instability at 2 h post-application, with 5/6 specimens in each group reaching or exceeding the 2 mm pathological displacement threshold. Specimen-level mean maximum total displacement did not differ significantly between groups, χ2(1) = 0.128, p = 0.721. Although variance ratios suggested numerically greater displacement variability in the wired-only group at individual load increments, Fligner-Killeen tests did not detect significant variance differences.

INTERPRETATION: At 2 h post-application, AASF did not significantly improve construct stability compared with wired-only fixation under cyclic lateral distraction loading up to 500 N. These findings suggest that stabilizing effects previously reported after longer GPC maturation periods should not be assumed immediately post-application. Larger studies evaluating additional early maturation timepoints and higher load magnitudes are required before postoperative recommendations can be made.