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Introduction Lower back pain due to degenerative disc disease is a therapeutic challenge in young patients. Although arthrodesis is currently the gold standard for surgical treatment, improvement in total disc replacement techniques makes it possible to preserve segmental mobility with good results in one-level surgery. Nevertheless, the French National Health Authority does not recommend total disc replacement for multilevel surgery. Thus, hybrid constructs that combine one-level disc replacement with arthrodesis have been developed for multilevel indications. Hypothesis The outcome of two-level lumbar disc arthroplasty does not differ from hybrid constructs. Methods The clinical and radiographic outcomes of disc arthroplasty were compared to hybrid constructs for two-level degenerative disc disease in 72 patients after a continuous follow-up of at least 2 years. The patients were divided into two groups that were similar for the indication and type of implants. Results There was no statistical difference in pain relief (−3.9 points versus −3.5 points for lumbar VAS) or reduction in ODI (−29.5% versus −27.0%) between TDR and hybrid constructs, respectively. There was no statistical difference in range of motion at the level of arthroplasty (8.4° versus 7.6°) and no kinematic dysfunction was identified. The re-operation rate at two years for persistent lumbar pain was respectively 6.7% for two-level disc arthroplasty and 4.3% for hybrid constructs. The complication rate was 4.8% and 8.7% respectively. Discussion No difference was found in this comparison of two homogeneous series between two-level disc arthroplasty and hybrid constructs for the treatment of degenerative disc disease after two years of follow-up. Two-level disc arthroplasty may be an alternative for young patients depending on an evaluation of long-term results. Level of evidence Cohort observational study level III.

Introduction It has been suggested that the indication for lumbar total disc replacement (LTDR) takes into account the local parameters, such as the type of disc disease demonstrated on MRI and the presence or absence of facet joint osteoarthritis. The type of preoperative sagittal curvature could also be taken into account. This study reports the clinical results of LTDRs depending on the type of sagittal spinal alignment. Material and methods Eighty patients were included in this prospective study, with a mean age of 41.7 years (range, 27–56 years). The clinical analysis took into account the lumbar VAS, the Oswestry Disability Index (ODI), and the preoperative frequency of painkiller use, at 1 year and at the last follow-up. The satisfaction index, return to work, and willingness to undergo the same treatment were also collected. The radiological study included the analysis of lumbar-pelvic parameters to distribute the patients according to the Roussouly classification. Results The mean follow-up was 59.1 months (range, 14–96 months). The type 1 group included four cases. Reduction of the VAS, the ODI score, and the frequency of painkiller use at the last follow-up were significant in type 2 and 3 patients, and non-significant for type 4. Eighty-five percent of type 2 patients and 87.5% of type 3 patients were satisfied or very satisfied with the surgery versus only 68% of the type 4 patients. In addition, 63% of the type 4 patients declared they would be willing to undergo the same treatment again versus 85% of the type 2 patients and 82.5% of the type 3 patients. It should also be noted that 67% of the patients in this series returned to work. Discussion and conclusion This study underscores the influence of the type of sagittal curvature on the clinical results of LTDR, with type 4 patients showing inferior clinical results because of a higher rate of residual lower back pain. The indication in LTDR should be reconsidered for discogenic lower back pain in type 4 patients.

The aim of total disc replacement (TDR) is to restore and maintain closer-to-physiology motion. Therefore, the factors that influence postoperative intervertebral motion have to be controlled. Factors such as disc height (DH), postoperative segmental lordosis (SL), implant design and positioning are still recognized to be influent. Otherwise, range of motion (ROM) distribution, between flexion and extension, appear to be influenced by obtaining parallel bearing surfaces, which depends on prosthesis endplate lordotic angulation. To assess in vivo the correlation between an intraoperative parameter (intraoperative segmental lordosis: ISL) and a postoperative parameter (postoperative segmental lordosis: PSL). To determine the advantage of ISL measurement on the improvement of the prosthetic endplate lordotic angulation choice. Radiological comparison between intraoperative and postoperative segmental parameters. Fifty-seven patients who received a TDR at one level, L4–L5 or L5–S1, with different prosthetic endplate lordotic angulations (0°, 5°, and 10°). Twenty-one consecutive patients underwent intraoperative measurement (ISL) on a lateral view, with a spacer at the mid-vertebral bony endplates (Group 1). ISL was correlated using a linear correlation test with PSL. Group 1 postoperative prosthesis endplate lordosis (PEL: angle between the bearing surfaces) were compared to those of 46 patients without intraoperative measurement (Group 2). The mean ISL and PSL angles were 12.2° (7–21°) and 13.9° (8–23°), respectively. We observed a strong linear correlation between ISL and PSL (r=0.78, P

SummaryIntraoperative spinal cord monitoring consists in a subcontinuous evaluation of spinal cord sensory-motor functions and allows the reduction the incidence of neurological complications resulting from spinal surgery. A combination of techniques is used: somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), neurogenic motor evoked potentials (NMEP), D waves, and pedicular screw testing. In absence of intraoperative neurophysiological testing, the intraoperative wake-up test is a true form of monitoring even if its latency long and its precision variable. A 2011 survey of 117 French spinal surgeons showed that only 36% had neurophysiological monitoring available (public healthcare facilities, 42%; private facilities, 27%). Monitoring can be performed by a neurophysiologist in the operating room, remotely using a network, or directly by the surgeon. Intraoperative alerts allow real-time diagnosis of impending neurological injury. Use of spinal electrodes, moved along the medullary canal, can determine the lesion level (NMEP, D waves). The response to a monitoring alert should take into account the phase of the surgical intervention and does not systematically lead to interruption of the intervention. Multimodal intraoperative monitoring, in presence of a neurophysiologist, in collaboration with the anesthesiologist, is the most reliable technique available. However, no monitoring technique can predict a delayed-onset paraplegia that appears after the end of surgery. In cases of preexisting neurological deficit, monitoring contributes little. Monitoring of the L1–L4 spinal roots also shows low reliability. Therefore, monitoring has no indication in discal and degenerative surgery of the spinal surgery. However, testing pedicular screws can be useful. All in all, thoracic and thoracolumbar vertebral deviations, with normal preoperative neurological examination are currently the essential indication for spinal cord monitoring. Its absence in this indication is a lost opportunity for the patient. If neurophysiological means are not available, intraoperative wake-up test is a minimal obligation.

Biphasic calcium phosphate particles (BCP), alone or combined with a cellulosic ether vehicle in an injectable composite material (COMP), were implanted in femurs of rabbits. The long-term follow-up (up to 78 weeks) indicated: (1) BCP and COMP induced a foreign-body inflammatory reaction but without fibrous encapsulation. Phagocytosis was mediated by mononucleated macrophages (MC) and giant multinucleated cells (GMNC). Phagocytosis was stronger with COMP and required the recruitment of GMNC while it primarily involved MC in the case of BCP. (2) There appeared to be no significant difference between the bone ingrowth in the defects packed with BCP (dBCP) and in those filled with COMP (dCOMP). Bone reconstruction mostly was achieved after 4 weeks in dBCP but took more time to reach the center of dCOMP. High bone remodeling was observed at the last evaluation times, especially in the case of COMP. (3) Degradation of the materials occurred mainly during the first 4 weeks and was more severe for COMP, which probably was related to the smaller granulometry of its mineral phase. Cell-mediated degradation went on for the 78 weeks and followed two processes: phagocytosis and/or extracellular dissolution of the calcium phosphate particles. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 368-375, 1998.

Macroporous biphasic calcium phosphate ceramics are biocompatible. Their physico-chemical structure is close to the mineral phase of the bone and provides bioactivity. Shortly after implantation in osseous area, dissolution appears with precipitation and formation of apatite crystals. Soon after osteoclastic resorption begins osteoconduction inside the macropores. Mechanical studies reveal a significant improvement in the mechanical properties due to the growth of the trabecular bone. Animal experiments in the spine have demonstrated bone penetration which allows a postero-lateral fusion. The rigidity of the fusion is equivalent to that obtained with bone graft. Macroporous biphasic calcium phosphate can be applied to fill bone defects and for postero-lateral spine fusion.

Resume La chirurgie correctrice de la scoliose a ete surveillee par un monitoring des potentiels evoques moteurs neurogenes, enregistres sur un nerf peripherique apres une stimulation electrique medullaire, en association aux potentiels evoques somesthesiques, chez 23 patients. Aucun echec technique n'a ete observe. Dans trois cas fut constatee une modification de ces potentiels: abolition definitive une fois, correlee a une tetraplegie peroperatoire apres test du reveil, et postoperatoire, diminution d'amplitude transitoires sans graves consequences neurologiques deux fois. Bien que la nature exacte de ces potentiels soit controversee et peut-etre d'origine sensitive antidromique, cette technique apparait facilement realisable, reproductible, plus rapide et plus sensible que les potentiels evoques somesthesiques, pour la detection d'anomalie de la conduction medullaire au cours de la correction chirurgicale de la scoliose sous anesthesie.

The osseous tissue response to transcortical rods plasma-sprayed with hydroxyapatite (HA) and Biphasic Calcium Phosphate (BCP), and also to unsprayed rods, was evaluated. Correlation between the histologie and the mechanical results revealed a difference of bonding behavior between HA coating and BCP coating. The formation of a lamellar bone directly deposited on the ceramic surface was faster with BCP compared to HA. Both sprayded rods exibited higher push-out strengths than unsprayed rods. The interfacial strength of unsprayed rods depended upon the surface rugosity. This study indicates that BCP ceramic provided a more efficient coating material for accelerated interface attachment.

Summary Introduction The aim of treatment of scolioses is to reduce deformities and restore balance in the spine. Hypotheses In rigid forms of scoliosis, associating anterior release could provide greater frontal and/or sagittal plane correction and improve balance in the spine. Patients and methods This study compared correction and long-term balance on two planes between two homogeneous groups of idiopathic rigid scolioses treated with and without thoracoscopic release. The study included rigid scolioses with less than 35% reducibility and a Cobb angle of more than 60°, who all underwent posterior correction using a rod rotation technique. There were 29 patients, 14 who underwent a one-step procedure (group A) and 15 a two-step procedure (group B), with the subgroups of kyphoscolioses and lordoscolioses determined in each group. Frontal balance, Cobb angle, thoracic kyphosis and the Jackson plumbline were measured on pre- and postoperative X-rays and at the final follow-up. Results The mean long-term final follow-up was 144 months for group A and 54 months for group B. Frontal plane correction was identical in groups A and B. Frontal balance was preserved in all cases at the final follow-up. Sagittal balance was not modified with or without anterior release. The thoracoscopic release step resulted in an additional correction of 15.5° (23%) of thoracic hyperkyphosis in patients with kyphoscoliosis ( P = 0.003). Discussion Thoracoscopy did not improve short term results in the Cobb angle or frontal or saggital balance. Nevertheless, enhanced correction of thoracic hyperkyphosis was obtained with this procedure. In this study, the association of thoracoscopic anterior release with posterior correction by rod rotation to treat rigid scolioses did not appear to improve results, except for the correction of thoracic hyperkyphosis. Level of evidence Level IV. Comparative and retrospective study.