Biomechanical Comparison of a Locking Compression Plate Combined With an Intramedullary Pin or a Polyetheretherketone Rod in a Cadaveric Canine Tibia Gap Model. Issue 8 (8th August 2014) - Beierer, Lucas H.
Abstract Objective To compare the biomechanical properties of a 10‐hole 3.5 mm locking compression plate (LCP) with 2 proximal and 2 distal bicortical locked screws reinforced with either a Steinmann pin of 30–40% the medullary diameter or a poly‐ether‐ether‐ketone (PEEK) rod of ∼75% the medullary diameter in a cadaveric tibia gap model. Study Design Ex vivo study. Sample Population Cadaveric canine tibias (n = 8 pair). Methods Each construct had a 10‐hole 3.5 mm LCP with 2 screws per fracture fragment using a comminuted tibia gap model. The Steinmann pin constructs had a 2.4 mm intramedullary pin whereas the PEEK‐rod constructs had a 6 mm intramedullary PEEK rod placed. Biomechanical testing included non‐destructive bi‐planar 4 point bending, torsion testing, and destructive axial compression. Testing produced the responses of failure load (N) in axial compression, stiffness (N/mm or N/°) in axial compression, torsion, lateral‐medial, and caudal‐cranial 4 point bending. Screw position within the PEEK‐rods was determined after explantation. Results The PEEK‐rod constructs were significantly stiffer in axial compression (P < .005), lateral‐medial 4 point bending (P < .001), and in torsional loading (P < .031) than the Steinman pin constructs. There was no significant difference between the constructs for stiffness in caudal‐cranial 4 point bending (P = .32). The PEEK‐rod constructs failed at a significantly higher load than the Steinmann pin constructs (P < .001). All constructs failed by yielding through plastic deformation. Each screw penetrated the PEEK rod in all constructs but the position of the screw varied. Conclusion PEEK‐rod constructs failed at significantly higher loads and were significantly stiffer in 4 point lateral‐medial bending, axial compression, and torsion when compared with Steinmann pin constructs.