Study benchmarks polyaxial combination-hole locking plate mechanics

A newly published veterinary biomechanics study offers early validation for a newer implant design: the 3.5-mm polyaxial combination-hole locking plate. In the Frontiers in Veterinary Science paper, published July 13, 2026, researchers found that the plate maintained consistent screw push-out strength and bending performance in bench testing, supporting the idea that a combination-hole configuration can preserve mechanical integrity while broadening screw-placement options. (frontiersin.org)

That question matters because locking plate systems have steadily expanded in veterinary orthopedics, with surgeons weighing tradeoffs among fixed-angle stability, contouring demands, and intraoperative flexibility. Review literature has noted that multiple locking plate systems are now available in the veterinary market, each with different biomechanical properties and clinical applications. Combination-hole concepts are also familiar from locking compression plate designs, which can accept either conventional or locking screws, but variable-angle polyaxial integration within that format has had relatively limited published baseline data in veterinary use. (researchportal.murdoch.edu.au)

In the new study, Brittany Losey and Karl Maritato evaluated 12-hole, 3.5-mm InVictos plates made from 316LVM stainless steel. The system uses a threaded polyaxial interface with double-helix locking screws, plus adjacent non-threaded regions that allow conventional cortical screw placement. The team performed axial push-out testing on 31 screws inserted at intended 0° angulation and tightened to 2.0 Nm, then ran three-point bending tests under ASTM F382 conditions with a 90-mm support span. Mean push-out forces ranged from 2,839 ± 471 N to 3,119 ± 274 N. Flexural strength ranged from 641 to 697 MPa, flexural stiffness from 133 to 141 N/mm, and maximum load to failure from 0.63 to 0.65 kN. (frontiersin.org)

The authors were careful not to overstate the results. They describe the data as foundational and descriptive, not comparative proof that this system outperforms others. Their discussion notes that previously published veterinary plate studies use different test setups, including push-out versus construct-level testing, three-point versus four-point bending, and isolated plates versus fracture-gap models, which makes direct head-to-head comparison difficult. That caution is important, especially because the study tested only monoaxial insertion conditions and did not address cyclic fatigue or whole-construct behavior. (frontiersin.org)

There does appear to be a broader industry backdrop. InVictos markets “CombiLOCK” plates as dual-purpose compression-polylocking implants and says its TPLO plates are made from 316LVM stainless steel and manufactured to ASTM, ISO, and FDA requirements. Meanwhile, Maritato’s MedVet profile notes that he has co-edited a textbook on locking implant technology and has developed orthopedic implants for dogs, underscoring that the paper comes from authors with direct familiarity with the implant category. The study’s conflict-of-interest and funding details should be reviewed directly by readers for any procurement or formulary decisions, but the publication itself is transparent that the tested implants were InVictos devices. (invictosortho.com)

Why it matters: For veterinary professionals, this study helps fill a narrow but practical evidence gap. Polyaxial systems are attractive because they can improve screw trajectory options in anatomically awkward fractures or revision settings, and combination holes may give surgeons more freedom to choose between locking and cortical fixation strategies during the case. What this paper adds is reassurance that, at least in baseline bench testing, that extra versatility did not obviously come at the cost of screw engagement or plate bending behavior. Still, clinicians should be cautious about extrapolating too far: implant choice depends on fracture pattern, patient size, contouring needs, cost, and how a full construct performs under cyclic physiologic loads, not just isolated plate mechanics. (frontiersin.org)

What to watch: The most useful follow-up would be standardized comparative studies against other veterinary locking systems, especially under cyclic loading, fracture-gap models, and variable-angle screw insertion, which the authors themselves identify as the next research need. If those data emerge, they’ll do more than confirm bench strength, they’ll help surgeons judge where polyaxial combination-hole plates fit in everyday fracture repair and whether the added flexibility justifies any added complexity or cost. (frontiersin.org)