Graft materials provide greater static strength to medial opening wedge high tibial osteotomy than when no graft is included

Adrian J Wilson,Simon Jobson,Raghbir Khakha,James Belsey,Stefan Maas,Dietrich Pape,Arnaud Diffo Kaze,James Faulkner

doi:10.1186/s40634-019-0184-6

Abstract

BackgroundThe purpose of this study was to compare the stability of medial opening-wedge high tibial osteotomy (MOWHTO) with and without different graft materials. Good clinical and radiological outcomes have been demonstrated when either using or not using graft materials during MOWHTO. Variations in the biomechanical properties of different graft types, regarding the stability they provide a MOWHTO, have not been previously investigated.MethodsA 10 mm biplanar MOWHTO was performed on 15 artificial sawbone tibiae, which were fixed using the Activmotion 2 plate. Five bones had OSferion60 wedges (synthetic group), five had allograft bone wedges (allograft group), and five had no wedges (control group) inserted into the osteotomy gap. Static compression was applied axially to each specimen until failure of the osteotomy. Ultimate load, horizontal and vertical displacements were measured and used to calculate construct stiffness and valgus malrotation of the tibial head.ResultsThe synthetic group failed at 6.3 kN, followed by the allograft group (6 kN), and the control group (4.5 kN). The most valgus malrotation of the tibial head was observed in the allograft group (2.6°). The synthetic group showed the highest stiffness at the medial side of the tibial head (9.54 kN·mm− 1), but the lowest stiffness at the lateral side (1.59 kN·mm-1). The allograft group showed high stiffness on the medial side of the tibial head (7.54 kN·mm− 1) as well as the highest stiffness on the lateral side (2.18 kN·mm− 1).ConclusionsThe use of graft materials in MOWHTO results in superior material properties compared to the use of no graft. The static strength of MOWHTO is highest when synthetic grafts are inserted into the osteotomy gap. Allograft wedges provide higher mechanical strength to a MOWHTO than when no graft used. In comparison to the synthetic grafts, allograft wedges result in the stiffness of the osteotomy being more similar at the medial and lateral cortices.

Highlights

The purpose of this study was to compare the stability of medial opening-wedge high tibial osteotomy (MOWHTO) with and without different graft materials
Previous research has shown that allograft and synthetic bone wedges have a similar outcome with regard to delayedand non-union (Lash et al, 2015; Slevin et al, 2016) but differ in relation to other complications, for example, the use of an allograft wedge runs the risk of disease transmission, whereas synthetic grafts have been associated with infection and soft-tissue irritation (Han et al, 2015)
The data from one specimen in the allograft group and one specimen in the synthetic group were not included in the final analysis due to the specimens accidentally being loaded prior to testing, resulting in the specimens failing abnormally early during their tests

Summary

Introduction

The purpose of this study was to compare the stability of medial opening-wedge high tibial osteotomy (MOWHTO) with and without different graft materials. Alternative internal fixators are gathering popularity with varying degrees of success with regards to clinical outcomes (pain and knee function) (Cotic et al, 2015) and material properties (construct strength and stiffness) having been reported (Diffo Kaze et al, 2015; Luo et al, 2015). The size 2 ActivMotion HTO plate (NewClip Technics, HauteGoulaine, France), for example, has been shown to allow a MOWHTO to resist the greatest load until failure under static compression testing, and provides the highest construct stiffness under cyclical testing, compared to the standard Tomofix plate and four other MOWHTO plates on the market (Diffo Kaze et al, 2015). Previous research has shown that allograft and synthetic bone wedges have a similar outcome with regard to delayedand non-union (Lash et al, 2015; Slevin et al, 2016) but differ in relation to other complications, for example, the use of an allograft wedge runs the risk of disease transmission, whereas synthetic grafts have been associated with infection and soft-tissue irritation (Han et al, 2015)

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