Biomechanical properties of five different currently used implants for open-wedge high tibial osteotomy

Abstract

BackgroundAs several new tibial osteotomy plates recently appeared on the market, the aim of the present study was to compare mechanical static and fatigue strength of three newly designed plates with gold standard plates for the treatment of medial knee joint osteoarthritis.MethodsSixteen fourth-generation tibial bone composites underwent a medial open-wedge high tibial osteotomy (HTO) according to standard techniques, using five TomoFix standard plates, five PEEKPower plates and six iBalance implants. Static compression load to failure and load-controlled cyclic fatigue failure tests were performed. Forces, horizontal and vertical displacements were measured; rotational permanent plastic deformations, maximal displacement ranges in the hysteresis loops of the cyclic loading responses and dynamic stiffness were determined.ResultsStatic compression load to failure tests revealed that all plates showed sufficient stability up to 2400 N without any signs of opposite cortex fracture, which occurred above this load in all constructs at different load levels. During the fatigue failure tests, screw breakage in the iBalance group and opposite cortex fractures in all constructs occurred only under physiological loading conditions (<2400 N). The highest fatigue strength in terms of maximal load and number of cycles performed prior to failure was observed for the ContourLock group followed by the iBalance implants, the TomoFix standard (std) and small stature (sm) plates. The PEEKPower group showed the lowest fatigue strength.ConclusionsAll plates showed sufficient stability under static loading. Compared to the TomoFix and the PEEKPower plates, the ContourLock plate and iBalance implant showed a higher mechanical fatigue strength during cyclic fatigue testing. These data suggest that both mechanical static and fatigue strength increase with a wider proximal T-shaped plate design together with diverging proximal screws as used in the ContourLock plate or a closed-wedge construction as in the iBalance design. Mechanical strength of the bone-implant constructs decreases with a narrow T-shaped proximal end design and converging proximal screws (TomoFix) or a short vertical plate design (PEEKPower Plate). Whenever high mechanical strength is required, a ContourLock or iBalance plate should be selected.

The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates

“…TomoFix HTO plates (DePuy Synthes, Zuchwil, Switzerland) have been shown to have lower stiffness and migrate more with cyclical loading than iBalance (Arthrex GmbH, Munich, Germany), Contour Lock (Arthrex), and PEEKPower (Arthrex) implants. 20 Despite these findings, TomoFix implants (without wedge blocks) are still the gold standard in HTO treatment and have lower complication rates than short spacer plates designed by competitors. 21 In laboratory-based studies, implants that produce higher construct stiffness also generally have greater fatigue resistance.…”

“…21 In laboratory-based studies, implants that produce higher construct stiffness also generally have greater fatigue resistance. 20,22,23 Clinically, however, more flexible implants can perform better in terms of healing, 24 indicating that mechanical properties such as strength and, more importantly, stiffness do not necessarily translate into improved clinical performance.…”

Influence of the Screw Positioning on the Stability of Locking Plate for Proximal Tibial Fractures: A Numerical Approach

“…A more stable fixation system could in fact allow reduction of the non-weight-bearing time, thus reducing the negative effects on a patient's functionality and speeding up the healing process. Several studies have been performed on this topic, focusing mainly on how the stability of the construct is influenced by the type and number of screws [17,47], or by the shape or positioning of the plate [8,18,39,48,49].…”

Computational comparison of different plating strategies in medial open-wedge high tibial osteotomy with lateral hinge fractures

“…Using HTO for medial compartmental KOA is currently popular because the locking plate and screws can provide excellent stability immediately after osteotomy, enabling the patient to start rehabilitation programs earlier than with the use of the traditional compression plate. Scholars have shown that MP with only the TomoFix locking plate stabilizes HTO with a medial open wedge (without LHF) and provides enough stability for bone healing [26][27][28]. However, when the lateral hinge is fractured, MP only does not provide adequate stability for bone healing at the osteotomy site and at the fractured lateral hinge.…”