Parameters influencing the outcome after total disc replacement at the lumbosacral junction. Part 2: distraction and posterior translation lead to clinical failure after a mean follow-up of 5 years

Abstract

Purpose The aim of the second part of the study was to investigate the influence of parameters that lead to increased facet joint contact or capsule tensile forces (disc height, lordosis, and sagittal misalignment) on the clinical outcome after total disc replacement (TDR) at the lumbosacral junction. Methods A total of 40 patients of a prospective cohort study who received TDR because of degenerative disc disease or osteochondrosis L5/S1 were invited to an additional follow-up for clinical (ODI and VAS for overall, back, and leg pain) and radiographic analysis (a change in disc height, lordosis, or sagittal vertebral misalignment compared with the preoperative state). Based on the final ODI, patients were retrospectively distributed into groups N (normal: \25 %) or F (failure C25 %) for radiographic parameter comparison. A correlation analysis was performed between the clinical and radiological results. Results A total of 34 patients were available at a mean follow-up of 59.5 months. Both groups (N = 24; F = 10 patients) presented a significant improvement in overall pain, back pain, and ODI over time. At the final follow-up, higher clinical scores correlated with a larger disc height, increased lordosis, and posterior translation of the superior vertebra, which was also reflected by significant differences in these parameters in the group comparison. Conclusions Parameters associated with increased facet joint capsule tensile forces lead to an inferior clinical outcome at mid-term follow-up. When performing TDR, we therefore suggest avoiding iatrogenic posterior translation and overdistraction (and consecutive lordosis).

The Michel Benoist and Robert Mulholland Yearly European Spine Journal Review: a survey of the “surgical and research” articles in the European Spine Journal, 2013

“…Why fewer of the TDR group were working at 5 years is not understood, as in the TDR group 59 % were totally pain free, compared with only 38 % in the fusion group. Two other papers adjacent to this dealt with the likelihood, for biomechanical reasons of TDR failure at the lumbosacral level [46,47]. In doing a TDR at the lumbosacral level with marked narrowing of the disc, one must avoid increasing segmental lordosis, and posterior translation of the superior vertebrae.…”

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

“…These observed increases agree with our second hypothesis. Thus, these predicted high loads might explain the clinical results of Strube et al (2013a), who demonstrated that an iatrogenic overdistraction is significantly associated with clinical failure after TDR. Furthermore, Leivseth et al (2006) showed that the amount of distraction is typically larger in L5-S1 than in L4-5, which might partially explain the unsatisfactory clinical results of a TDR in the lumbosacral segment L5-S1 (Siepe et al, 2008(Siepe et al, , 2007.…”

“…Furthermore, Leivseth et al (2006) showed that the amount of distraction is typically larger in L5-S1 than in L4-5, which might partially explain the unsatisfactory clinical results of a TDR in the lumbosacral segment L5-S1 (Siepe et al, 2008(Siepe et al, , 2007. The complete postoperative RoM in the sagittal plane (sum of the RoF and RoE) was measured in patients in several clinical studies, and a direct correlation with the resultant clinical outcome was investigated (e.g., Johnsen et al, 2013;Leivseth et al, 2010;Leivseth et al, 2006;Siepe et al, 2009;Strube et al, 2013a). However, the resultant complete RoM appears to be insensitive to detecting the elementary mechanical changes shown herein (Fig.…”

“…Previous clinical studies emphasized the importance of iatrogenic distraction for surgical success (Strube et al, 2013a). Therefore, the first sensitivity study was designed to exclusively analyze the elementary effects of an iatrogenic distraction in models with different disc heights on the FJFs, FCLFs and segmental RoM.…”

“…They also showed that patients with a preoperative larger disc height reported significantly lower subjective patient satisfaction rates . Aside from preoperative radiological parameters, in a combined clinical and computational study, Strube et al (2013a) and Rohlmann et al (2013) emphasized that an iatrogenic posterior translation of L5 with respect to S1 followed by an increase in the facet capsule ligament forces as well as an overdistraction followed by an increase of lordosis in L5-S1 leads to inferior clinical outcomes. 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.…”