In Situ Contact Analysis of the Prosthesis Components of Prodisc-L in Lumbar Spine Following Total Disc Replacement

Abstract

The in situ function of the TDR prosthesis was highly dependent on how well the device could incorporate itself into the mechanical environment in the disc space, which has been determined by the rest of the spinal structures, including the retained disc anulus, articular facets, ligaments, vertebrae, and muscular stabilizers. The different contact interaction of the artificial disc components revealed here could be attributed to the violation of this mechanical environment which, in turn, may bring adverse effects to those spinal elements.

In silico evaluation of a new composite disc substitute with a L3–L5 lumbar spine finite element model

“…Such result supports previous interpretations reported about semi-constrained BoS implants [37]. Nonetheless, FJ contact forces computed with the updated devices were within the range of in vitro measured values and did not show relative alterations of up to 150-660% as predicted with BoS implant models [1,2,37].…”

“…Under extension, earlier FE predictions showed that BoS implants could affect surgical level ROM by 50% [37] to 120-140% [47] at 7.5 Nm and by 80-90% under 10 Nm [1,2]. In the present study the best device version led to a maximum ROM relative change of about 50%.…”

“…vertebral body fracture [6], prosthesis migration into the adjacent bone [4], spontaneous ankylosis [4,33], and accelerated FJ degeneration [39] can be related to the BoS design as numerically suggested [2,8,35]. Also because prosthesis shapes are standardized geometrical patient-specificity is limited and strong correlations exist between prosthesis placement and clinical complications [4].…”

Biomechanics of the L5–S1 motion segment after total disc replacement – Influence of iatrogenic distraction, implant positioning and preoperative disc height on the range of motion and loading of facet joints

“…However, a crucial relationship between individual preoperative disc height, iatrogenic distraction, resultant postoperative biomechanical changes (segmental range of motion (RoM); facet joint loading) and resultant clinical results remains to be established. Finite element (FE) models of the lumbar spine have been introduced to clarify these elementary biomechanical relationships (Chen et., 2009;Chung et al, 2009;Le Huec et al, 2010;Rohlmann et al, 2009a;Rundell et al, 2012;Schmidt et al, 2012;Zander et al, 2009). These models can provide detailed insight into the segmental kinematics and loading of the facet joints (facet joint forces (FJFs) and facet capsule ligament forces (FCLFs)).…”

We Need to Talk about Lumbar Total Disc Replacement

“…147 Ultimately, in situ function of the ProDisc-L will be determined by how well it is incorporated into the mechanical environment within the disc space in vivo, which, in turn, will be determined by other spinal structures (such as ligaments, articular facets, vertebrae, and muscular stabilizers); violation of this mechanical environment could adversely impact LTDR patients, but, frustratingly, such violation also confounds biomechanical and kinematic studies. 639 Clinical concerns regarding facet arthrosis following LTDR were first published in 2007, when a degradation of index-level facet joints were seen in 36% and 32% of patients implanted with SB Charite and ProDisc II LADs, respectively, in a series of 61 patients followed up for a minimum of 3 years. 187 These results were replicated in a series of 32 patients (41 ProDisc II LADs) with a minimum follow-up of 2 years, in which progression of indexlevel facet degeneration was observed in 29% of cases, although it was noted that risk of such progression was related to malposition of the prosthesis on the frontal plane and/or to 2-level LTDR.…”