Interfragmentary Motion in Tibial Osteotomies Stabilized With Ring Fixators

What Are the Biomechanical Properties of the Taylor Spatial Frame™?

“…Data were recorded for three testing cycles for each construct configuration. Physiologic loading was considered to consist of 500 N axial loading, 20 Nm bending, and 5 Nm torsional load, being analogous to loads shown to be supported by a tibial frame during normal gait at 30 days postoperatively [8,32].…”

“…There is general consensus that a certain level of axial strain is desirable and necessary to stimulate bone healing with, among others, Kenwright and Goodship [22], as early as 1989, reporting increased callus mineralization and fracture stiffness in ovine tibial fractures with approximately 16% axial strain compared with more rigid fixation, although this was seen to deteriorate in quality somewhat with increased strains of up to 66% [10,13,17,22,34,36]. Likewise, although there is less agreement on this, it generally is considered that shear strain, whether linear or rotational, is detrimental to bone healing and should be limited where possible [3,8,10,29,36]. Relating this to the current study, given the nonclinically representative nature of the models tested and infinite variability of possible fracture patterns, it is not possible to extrapolate the precise change in mechanical behavior that would be produced at a specific fracture site by use of a TSF.…”

“…This combination is thought to generate an osteogenic mechanical environment [8,10,11,17,36], and the biomechanical theory has been supported by clinical results [12,33].…”

Temporal Variation in Fixation Stiffness Affects Healing by Differential Cartilage Formation in a Rat Osteotomy Model

“…The IFM is also influenced by the load on the operated leg due to gravity and muscle forces [7,14,20,36,43]. For a similar loading condition, the fixation stiffness is the dominating factor for the IFM [14]. IFM reportedly is not markedly altered during various different loading conditions [14], although the stiffness of the fixation correlates with the IFM [13].…”

“…Clinically, the mechanical environment can be altered through increasing the amount of interfragmentary movement (IFM) by reducing the fixation stiffness of interlocked nails [2,4,[38][39][40][41][42] or external fixators [12,17,28]. The IFM is also influenced by the load on the operated leg due to gravity and muscle forces [7,14,20,36,43]. For a similar loading condition, the fixation stiffness is the dominating factor for the IFM [14].…”