Bryan颈椎间盘假体置换术对脊髓型颈椎病患者疗效及颈椎生物力学的影响

目的:探讨Bryan颈椎间盘假体置换术对脊髓型颈椎病患者疗效及颈椎生物力学的影响。方法:选取2015年1月到2016年12月期间在我院接受治疗的脊髓型颈椎病患者48例,根据手术方式的不同将其分为植骨融合组(25例)和假体置换组(23例),其中植骨融合组采用颈椎前路减压植骨融合术进行治疗,假体置换组采用Bryan颈椎间盘假体置换术进行治疗。比较两组患者的日本骨科协会(JOA)颈椎评分、颈椎功能障碍指数(NDI)评分、视觉模拟疼痛量表(VAS)评分、颈椎生理曲度、颈椎活动度、手术节段活动度、上邻近节段活动度、下邻近节段活动度,并比较两组患者的并发症情况。结果:术后12个月假体置换组的NDI评分明显低于植骨融合组(P0.05);术后6个月、术后12个月植骨融合组的颈椎活动度低于假体置换组(P0.05);术后1个月、术后3个月、术后6个月、术后12个月假体置换组的手术节段活动度高于植骨融合组(P0.05);术后12个月植骨融合组的上邻近节段活动度、下邻近节段活动度高于假体置换组(P0.05);两组患者随访期间颈部轴性症状发生率比较差异有统计学意义(P0.05)。结论:与颈椎前路减压植骨融合术比较,Bryan颈椎间盘假体置换术对脊髓型颈椎病患者的远期疗效更佳,可更好的改善患者的颈椎生物力学,降低颈部轴性症状发生率,值得临床推广应用。     

Biomechanical analysis of the anterior cervical fusion

This paper presents a biomechanical analysis of the cervical C5–C6 functional spine unit before and after the anterior cervical discectomy and fusion. The aim of this work is to study the influence of the medical procedure and its instrumentation on range of motion and stress distribution. First, a three-dimensional finite element model of the lower cervical spine is obtained from computed tomography images using a pipeline of image processing, geometric modelling and mesh generation software. Then, a finite element study of parameters' influence on motion and a stress analysis at physiological and different post-operative scenarios were made for the basic movements of the cervical spine. It was confirmed that the results were very sensitive to intervertebral disc properties. The insertion of an anterior cervical plate influenced the stress distribution at the vertebral level as well as in the bone graft. Additionally, stress values in the graft decreased when it is used together with a cage.     

Biomechanical analysis of the anterior cervical fusion

This paper presents a biomechanical analysis of the cervical C5-C6 functional spine unit before and after the anterior cervical discectomy and fusion. The aim of this work is to study the influence of the medical procedure and its instrumentation on range of motion and stress distribution. First, a three-dimensional finite element model of the lower cervical spine is obtained from computed tomography images using a pipeline of image processing, geometric modelling and mesh generation software. Then, a finite element study of parameters' influence on motion and a stress analysis at physiological and different post-operative scenarios were made for the basic movements of the cervical spine. It was confirmed that the results were very sensitive to intervertebral disc properties. The insertion of an anterior cervical plate influenced the stress distribution at the vertebral level as well as in the bone graft. Additionally, stress values in the graft decreased when it is used together with a cage.     

脊髓型颈椎病手术治疗新进展

颈椎病是指因颈椎间盘退行性变及其继发改变所导致的脊髓、神经、血管等结构受压而表现出的一系列临床症状和体征,根据发病机制可分为神经根型、脊髓型、椎动脉型、交感型、混合型,以及近年来受到重视的脊髓前动脉受压症等,脊髓型颈椎病是其中一种严重类型,保守治疗效果不佳,目前临床上常用的治疗方法为手术治疗。根据患者病情手术的入路可分为前路和后路,本文分别从手术的前后入路出发,对近年来脊髓型颈椎病手术治疗方式的进展作一综述。     

Biomechanicsl evaluation of a stand-alone interbody fusion cage based on porous TiO2/glass-ceramic on the human cervical spine]

Recently, there has been a rapid increase in the use of cervical spine interbody fusion cages, differing in design and biomaterial used, in competition to autologous iliac bone graft and bone cement (PMMA). Limited biomechanical differences in primary stability, as well as advantages and disadvantages of each cage or material have been investigated in studies, using an in vitro human cervical spine model. 20 human cervical spine specimens were tested after fusion with either a cubical stand-alone interbody fusion cage manufactured from a new porous TiO2/glass composite (Ecopore) or PMMA after discectomy. Non-destructive biomechanical testing was performed, including flexion/extension and lateral bending using a spine testing apparatus. Three-dimensional segmental range of motion (ROM) was evaluated using an ultrasound measurement system. ROM increased more in flexion/extension and lateral bending after PMMA fusion (26.5%/36.1%), then after implantation of the Ecopore-cage (8.1%/7.8%). In this first biomechanical in vitro examination of a new porous ceramic bone replacement material a) the feasibility and reproducibility of biomechanical cadaveric cervical examination and its applicability was demonstrated, b) the stability of the ceramic cage as a stand alone interbody cage was confirmed in vitro, and c) basic information and knowledge for our intended biomechanical and histological in vivo testing, after implantation of Ecopore in cervical sheep spines, were obtained.     

Good results of circumferential spine fusion in smokers, using autograft and allograft

We have examined the rates of anterior interbody fusion of lumbar spine segments following fusion with a fresh frozen femoral head allograft in 25 heavy smoking patients. They were all stabilized both anteriorly and posteriorly. The indications for surgery were: degenerative disc disease, degenerative spondylolisthesis and nonunion following previous posterolateral fusion of lumbar spine segments. Only patients who had fusion of one or two lumbar segments were included. They all were stabilized posteriorly with pedicle screws and autogenic iliac bone graft. The fusion was assessed at least one year after surgery according to plan X-rays as “Solid”, “Questionable” or “Failure”. One patient was found at follow up not fused, in another one the fusion was “questionable” and all the other 23 patients had an anterior solid fusion. Clinically, 84% of the patients had the same or improved work status as before surgery and 68% acknowledged that they were satisfied with the surgical results. No major complications were recorded and the average length of hospitalization was 10.3 days. This revised version was published online in July 2006 with corrections to the Cover Date.     

Numerical simulations of bone remodelling and formation following nucleotomy

Nucleotomy is the gold standard treatment for disc herniation and has proven ability to restore stability by creating a bony bridge without any additional fixation. However, the evolution of mineral density in the extant and new bone after nucleotomy and fixation techniques has to date not been investigated in detail. The main goal of this study is to determine possible mechanisms that may trigger the bone remodelling and formation processes.With that purpose, a finite element model of the L4–L5 spinal segment was used. Bone mineral density (BMD), new tissue composition, and endplate deflection were determined as indicators of lumbar fusion. A bone-remodelling algorithm and a tissue-healing algorithm, both mechanically driven, were implemented to predict vertebral bone alterations and fusion patterns after nucleotomy, internal fixation, and anterior plate placement.When considering an intact disc height, neither nucleotomy nor internal fixation were able to provide the necessary stability to promote bony fusion. However, when 75% of the disc height was considered, bone fusion was predicted for both techniques. By contrast, an anterior plate allowed bone fusion at all disc heights. A 50% disc-height reduction led to osteophyte formation in all cases. Changes in the intervertebral disc tissue caused BMD alterations in the endplates.From this observations it can be drawn that fusion may be self-induced by controlling the mechanical stabilisation without the need of additional fixation. The amount of tissue to be removed to achieve this stabilisation remains to be determined.     

Application of a stand-alone interbody fusion cage based on a novel porous TiO2/glass composite. I. Implantation in the sheep cervical spine and radiological evaluation]

Animals are becoming more and more common as in vitro and in vivo models for the human spine. Especially the sheep cervical spine is stated to be of good comparability and usefulness in the evaluation of in vivo radiological, biomechanical and histological behaviour of new bone replacement materials, implants and cages for cervical spine interbody fusion. In preceding biomechanical in vitro examination human cervical spine specimens were tested after fusion with either a cubical stand-alone interbody fusion cage manufactured from a new porous TiO/glass composite (Ecopore) or polymethyl-methacrylate (PMMA) after discectomy. First experience with the use of the new material and its influence on the primary stability after in vitro application were gained. After fusion of 10 sheep cervical spines in the levels C2/3 and C4/5 in each case with PMMA and with an Ecopore-cage, radiologic as well as computertomographic examinations were performed postoperatively and every 4 weeks during the following 2 and 4 months, respectively. Apart from establishing our animal model, we analysed the radiological changes and the degree of bony fusion of the operated segments during the course. In addition we performed measurements of the corresponding disc space heights (DSH) and intervertebral angles (IVA) for comparison among each other, during the course and with the initial values. Immediately after placement of both implants in the disc spaces the mean DSH and IVA increased (34.8% and 53.9%, respectively). During the following months DSH decreased to a greater extent in the Ecopore-segments than in the PMMA-segments, even to a value below the initial value (p>0.05). Similarly, the IVA decreased in both groups in the postoperative time lapse, but more distinct in the Ecopore-segments (p<0.05). These changes in terms of a subsidence of the implants, were confirmed morphologically in the radiological examination in the course. The radiologically evaluated fusion, i.e. bony bridging of the operated segments, was more pronounced after implantation of an Ecopore-cage (83%), than after PMMA interposition (50%), but did not gain statistical significance. In this first in vivo examination of our new porous ceramic bone replacement material we showed its application in the spondylodesis model of the sheep cervical spine. Distinct radiological changes regarding evident subsidence and detectable fusion of the segments, operated on with the new biomaterial, were seen. We demonstrated the radiological changes of the fused segments during several months and analysed them morphologically, before the biomechanical evaluation will be presented in a subsequent publication.     

Biomechanical evaluation of a novel lumbosacral axial fixation device

BACKGROUND: Interbody arthrodesis is employed in the lumbar spine to eliminate painful motion and achieve stability through bony fusion. Bone grafts, metal cages, composite spacers, and growth factors are available and can be placed through traditional open techniques or minimally invasively. Whether placed anteriorly, posteriorly, or laterally, insertion of these implants necessitates compromise of the anulus--an inherently destabilizing procedure. A new axial percutaneous approach to the lumbosacral spine has been described. Using this technique, vertical access to the lumbosacral spine is achieved percutaneously via the presacral space. An implant that can be placed across a motion segment without compromise to the anulus avoids surgical destabilization and may be advantageous for interbody arthrodesis. The purpose of this study was to evaluate the in vitro biomechanical performance of the axial fixation rod, an anulus sparing, centrally placed interbody fusion implant for motion segment stabilization. METHOD OF APPROACH: Twenty-four bovine lumbar motion segments were mechanically tested using an unconstrainedflexibility protocol in sagittal and lateral bending, and torsion. Motion segments were also tested in axial compression. Each specimen was tested in an intact state, then drilled (simulating a transaxial approach to the lumbosacral spine), then with one of two axial fixation rods placed in the spine for stabilization. The range of motion, bending stiffness, and axial compressive stiffness were determined for each test condition. Results were compared to those previously reported for femoral ring allografts, bone dowels, BAK and BAK Proximity cages, Ray TFC, Brantigan ALIF and TLIF implants, the InFix Device, Danek TIBFD, single and double Harms cages, and Kaneda, Isola, and University plating systems. RESULTS: While axial drilling of specimens had little effect on stiffness and range of motion, specimens implanted with the axial fixation rod exhibited significant increases in stiffness and decreases in range of motion relative to intact state. When compared to existing anterior, posterior, and interbody instrumentation, lateral and sagittal bending stiffness of the axial fixation rod exceeded that of all other interbody devices, while stiffness in extension and axial compression were comparable to plate and rod constructs. Torsional stiffness was comparable to other interbody constructs and slightly lower than plate and rod constructs. CONCLUSIONS: For stabilization of the L5-S1 motion segment, axial placement of implants offers potential benefits relative to traditional exposures. The preliminary biomechanical data from this study indicate that the axial fixation rod compares favorably to other devices and may be suitable to reduce pathologic motion at L5-S1, thus promoting bony fusion.     

Codman颈椎前路钢板系统在脊髓型颈椎病中的应用（附96例报道）

目的：探讨Codman颈椎前路钢板系统治疗脊髓型颈椎病的临床运用疗效。方法：采用Codman颈椎前路钢板系统对96例脊髓型颈椎病患者行前路减压,植骨融合,钢板内固定术。结果：术后经6-14月门诊复查或随诊,全部患者术后症状明显改善或消失,颈椎椎间高度维持良好,植骨全部融合,未出现钢板、螺钉、松动或断裂。结论：Codman颈椎前路钢板系统是一种操作较为方便、安全、有效,固定牢靠的颈椎内固定器械。     

Finite Element Analysis of Interbody Cages in a Human Lumbar Spine

Abstract

An innovative surgical procedure is vertebral stabilization by interbody cages. It is currently being used to separate and stabilize vertebral bodies and to promote bony fusion of the vertebrae onto or through the cages. This surgery, at some spine levels, can be performed through a laparoscope as an outpatient procedure with low morbidity. Because the procedure is new, little structural information is available on the interbody cages. The objective of this study was to evaluate the human lumbar spine stabilized by interbody cages biomechanically. The finite element method was used to compare cage designs by considering stresses in the cage and in the bone as well as relative displacements between the cage and the adjacent bone at the interface. The biomechanical evaluation considered different bone densities and considered axial, torsional, and bending loads on the lumbar spine. Stress analysis predicts local regions of stress concentration that could be damaging to cancellous bone and will likely require a remodeling response for local damage. This study predicts relative micromotion that could cause the bone resorption and fibrous tissue formation on the contact surfaces of the cage. The geometric constraints caused by the use of two cages will reduce the relative motion and therefore be more likely to allow bone ingrowth at the posterocentral contact region. Finite element analysis suggests that cages are a promising method for separation and stabilization of the vertebral bodies.     

Finite Element Analysis of Interbody Cages in a Human Lumbar Spine

An innovative surgical procedure is vertebral stabilization by interbody cages. It is currently being used to separate and stabilize vertebral bodies and to promote bony fusion of the vertebrae onto or through the cages. This surgery, at some spine levels, can be performed through a laparoscope as an outpatient procedure with low morbidity. Because the procedure is new, little structural information is available on the interbody cages. The objective of this study was to evaluate the human lumbar spine stabilized by interbody cages biomechanically. The finite element method was used to compare cage designs by considering stresses in the cage and in the bone as well as relative displacements between the cage and the adjacent bone at the interface. The biomechanical evaluation considered different bone densities and considered axial, torsional, and bending loads on the lumbar spine. Stress analysis predicts local regions of stress concentration that could be damaging to cancellous bone and will likely require a remodeling response for local damage. This study predicts relative micromotion that could cause the bone resorption and fibrous tissue formation on the contact surfaces of the cage. The geometric constraints caused by the use of two cages will reduce the relative motion and therefore be more likely to allow bone ingrowth at the posterocentral contact region. Finite element analysis suggests that cages are a promising method for separation and stabilization of the vertebral bodies.     

Meta-Analysis Comparing Zero-Profile Spacer and Anterior Plate in Anterior Cervical Fusion

Background

Anterior plate fusion is an effective procedure for the treatment of cervical spinal diseases but is accompanied by a high incidence of postoperative dysphagia. A zero profile (Zero-P) spacer is increasingly being used to reduce postoperative dysphagia and other potential complications associated with surgical intervention. Studies comparing the Zero-P spacer and anterior plate have reported conflicting results.

Methodology

A meta-analysis was conducted to compare the safety, efficacy, radiological outcomes and complications associated with the use of a Zero-P spacer versus an anterior plate in anterior cervical spine fusion for the treatment of cervical spinal disease. We comprehensively searched PubMed, Embase, the Cochrane Library and other databases and performed a meta-analysis of all randomized controlled trials (RCTs) and prospective or retrospective comparative studies assessing the two techniques.

Results

Ten studies enrolling 719 cervical spondylosis patients were included. The pooled data showed significant differences in the operation time [SMD = –0.58 (95% CI = −0.77 to 0.40, p < 0.01)] and blood loss [SMD = −0.40, 95% CI (−0.59 to –0.21), p < 0.01] between the two groups. Compared to the anterior plate group, the Zero-P group exhibited a significantly improved JOA score and reduced NDI and VAS. However, anterior plate fusion had greater postoperative segmental and cervical Cobb’s angles than the Zero-P group at the last follow-up. The fusion rate in the two groups was similar. More importantly, the Zero-P group had a lower incidence of earlier and later postoperative dysphagia.

Conclusions

Compared to anterior plate fusion, Zero-P is a safer and effective procedure, with a similar fusion rate and lower incidence of earlier and later postoperative dysphagia. However, the results of this meta-analysis should be accepted with caution due to the limitations of the study. Further evaluation and large-sample RCTs are required to confirm and update the results of this study.     

Cervical Total Disc Replacement is Superior to Anterior Cervical Decompression and Fusion: A Meta-Analysis of Prospective Randomized Controlled Trials

Background

Despite being considered the standard surgical procedure for symptomatic cervical disc disease, anterior cervical decompression and fusion invariably accelerates adjacent segment degeneration. Cervical total disc replacement is a motion-preserving procedure developed as a substitute to fusion. Whether cervical total disc replacement is superior to fusion remains unclear.

Methods

We comprehensively searched PubMed, EMBASE, Medline, and the Cochrane Library in accordance with the inclusion criteria to identify possible studies. The retrieved results were last updated on December 12, 2014. We classified the studies as short-term and midterm follow-up.

Results

Nineteen randomized controlled trials involving 4516 cases were identified. Compared with anterior cervical decompression and fusion, cervical total disc replacement had better functional outcomes (neck disability index [NDI], NDI success, neurological success, neck pain scores reported on a numerical rating scale [NRS], visual analog scales scores and overall success), greater segmental motion at the index level, fewer adverse events and fewer secondary surgical procedures at the index and adjacent levels in short-term follow-up (P < 0.05). With midterm follow-up, the cervical total disc replacement group indicated superiority in the NDI, neurological success, pain assessment (NRS), and secondary surgical procedures at the index level (P < 0.05). The Short Form 36 (SF-36) and segmental motion at the adjacent level in the short-term follow-up showed no significant difference between the two procedures, as did the secondary surgical procedure rates at the adjacent level with midterm follow-up (P > 0.05).

Conclusions

Cervical total disc replacement presented favorable functional outcomes, fewer adverse events, and fewer secondary surgical procedures. The efficacy and safety of cervical total disc replacement are superior to those of fusion. Longer-term, multicenter studies are required for a better evaluation of the long-term efficacy and safety of the two procedures.     

Biomechanical analysis of Graf's dynamic spine stabilisation system ex vivo.

The most frequent causes of chronic lumbar spine instability are of degenerative or traumatic origin. Numerous anterior and posterior stabilisation devices were developed for anatomical reconstruction of the spinal alignment and fusion of the spine to restore stability. Fusion of the spine results in increased load of adjacent segments with an increased risk of secondary degeneration which might result in instability or stenosis. To avoid the disadvantages of static devices, Graf developed a method of dynamic surgical treatment of spinal column instabilities, which is based on the principle of flexible stabilisation. This study is analysing the kinematics of discoligamentary intact motion segments compared with the experimentally destabilised human lumbar spine and the influence of Graf's stabilisation. According to our results, rotational instabilities cannot be satisfactorily stabilised by Graf's ligamentoplasty. With the present ex vivo study, it could be shown that it is possible to restore stability after discoligamentary lesion and after facetectomy using Graf's dynamic lordosis ligamentoplasty.     

Hydroxyapatite ceramics in multilevel cervical interbody fusion - is there a role?

The aim of this study is to evaluate the efficacy of hydroxyapatite grafts in multilevel cervical interbody fusion during the one year follow-up. A total of 86 patients with degenerative cervical disc disease underwent all together 224 cervical interbody fusion procedures in which either Smith-Robinson or Cloward type hydroxyapatite grafts were used. The surgeries included radiculopathy in 38 cases, myelopathy in 20 cases and myeloradicuopathy in 28 patients. In 65 out of 86 patients, fusion was followed by an anterior instrumentation (plating). Postoperatively, patients were followed for a mean of 15.64 (range 11-23.3) months. All patients underwent radiography to evaluate fusion and the axis curvature. Excellent clinical results (86%), described as a complete or partial relief of symptoms with full return to preop activity, were obtained in patients with radiculopathy. There were 5 grafts mobilizations and one graft fracture. Two grafts extruded in non-instrumented patients and required repeated surgery. There were other three reoperations due to the hardware problems. One year fusion rate was obtained at 86% for two-level surgery, 80.1% for three-level surgery and 74% for four-level surgery. The mean (SD) hospital stay was 3.8 (0.7) days. A hydroxyapatite cheramic can be a very effective synthetic material for multilevel cervical interbody fusion. It is characterized by a high fusion rate and a small percentage of graft-related complications, especially when fusion procedure is followed by plating.     

前路椎间盘减压融合与前路椎体次全切除减压融合治疗多节段颈椎病的疗效比较

目的:探索前路椎间盘减压融合与前路椎体次全切除减压治疗多节段颈椎病的疗效,为临床手术方式的选择提供依据。方法:收集我院骨科2008年6月到2014年6月收治的多节段颈椎病患者26例,按照患者手术方式分为研究组(13例)和对照组(13例),研究组给予前路椎间盘减压融合治疗,对照组给予前路椎体次全切除减压治疗,对比两组手术时间、术中出血量、术后住院时间,记录并分析两组术前和术后3月、6月、12个月JOA评分、颈椎总活动度、颈椎曲度、颈椎节段高度。结果:研究组手术时间、术中出血量低于对照组(P0.05);两组JOA评分术前、术后3月、6月、12个月逐渐升高(P0.05),术后12月组间差异有统计学意义(P0.05)。两组颈椎总活动度术前、术后3月、6月、12个月逐渐降低(P0.05),但是术后同时期组间差异无统计学意义(P0.05)。两组颈椎曲度与颈椎节段高度术后3月、6月、12个月差异有统计学意义(P0.05)。结论:前路椎间盘减压融合治疗多节段颈椎病较前路椎体次全切除减压治疗效果好,手术时间短、术中出血量少,并且颈椎曲度和节段高度恢复好。     

SURGICAL TREATMENT OF CERVICAL OSTEOARTHRITIS

The early results of anterior cervical intervertebral disc excision and fusion (Cloward operation) together with removal of associated arthritic bone spurs pressing on nerves and spinal cord give promise of relief of pain and muscle weakness in patients who have this form of cervical osteoarthritis.Eighty-five per cent of a group of patients with neurologic pain caused by compression of this kind were relieved by this operation. The approach to the cervical vertebrae is made by an incision into the front of the neck and the diseased disc and arthritic spurs are removed by drilling a half-inch hole into the edges of the vertebrae. The remaining fragments of disc are curetted away. The hole is plugged with a bone dowel. The patients had less pain and a more rapid convalescence than with the usual posterior laminectomy for chronic disc disease.     

The incidence of adjacent segment degeneration after cervical disc arthroplasty (CDA): a meta analysis of randomized controlled trials

Background

Cervical disc arthroplasty is being used as an alternative degenerative disc disease treatment with fusion of the cervical spine in order to preserve motion. However, whether replacement arthoplasty in the spine achieves its primary patient centered objective of lowering the frequency of adjacent segment degeneration is not verified yet.

Methodology

We conducted a meta-analysis according to the guidelines of the Cochrane Collaboration using databases including PubMed, Cochrane Central Register of Controlled Trials and Embase. The inclusion criteria were: 1) Randomized, controlled study of degenerative disc disease of the cervical spine involving single segment or double segments using Cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) as controls; 2) A minimum of two-year follow-up using imaging and clinical analyses; 3) Definite diagnostic evidences for “adjacent segment degeneration” and “adjacent segment disease”; 4) At least a minimum of 30 patients per population. Two authors independently selected trials; assessed methodological quality, extracted data and the results were pooled.

Results

No study has specifically compared the results of adjacent segment degenerative; Two papers describing 140 patients with 162 symptomatic cervical segment disorders and compared the rate of postoperative adjacent segment disease development between CDA and ACDF treatments, three publications describing the rate of adjacent-segment surgery including 1273 patients with symptomatic cervical segments. The result of the meta-analysis indicates that there were fewer the rate of adjacent segment disease and the rate for adjacent-segment surgery comparing CDA with ACDF, but the difference was not statistically significant.

Conclusions

Based on available evidence, it cannot be concluded, that CDA can significantly reduce the postoperative rate of the adjacent segment degenerative and adjacent segment disease. However, due to some limitations, the results of this meta-analysis should be cautiously accepted, and further studies are needed.     

Application of a stand-alone interbody fusion cage based on a novel porous TiO2/glass ceramic--2: Biomechanical evaluation after implantation in the sheep cervical spine]

Animals are becoming more and more common as in vivo models for the human spine. Especially the sheep cervical spine is stated to be of good comparability and usefulness in the evaluation of in vivo radiological, biomechanical and histological behaviour of new bone replacement materials, implants and cages for cervical spine interbody fusion. In preceding biomechanical in vitro examinations human cervical spine specimens were tested after fusion with either a cubical stand-alone interbody fusion cage manufactured from a new porous TiO2/glass composite (Ecopore) or polymethylmethacrylate (PMMA) after discectomy. Following our first experience with the use of the new material and its influence on the primary stability after in vitro application we carried out fusions of 20 sheep cervical spines levels with either PMMA or an Ecopore-cage, and performed radiological examinations during the following 2-4 months. In this second part of the study we intended the biomechanical evaluation of the spine segments with reference to the previously determined morphological findings, like subsidence of the implants, significant increase of the kyphosis angle and degree of the bony fusion along with the interpretation of the results. 20 sheep cervical spines segments with either PMMA- or Ecopore-fusion in the levels C2/3 and C4/5 were tested, in comparison to 10 native corresponding sheep cervical spine segments. Non-destructive biomechanical testing was performed, including flexion/extension, lateral bending and axial rotation using a spine testing apparatus. Three-dimensional range of motion (ROM) was evaluated using an ultrasound measurement system. In the native spine segments C2/3 and C4/5 the ROM increased in cranio-caudal direction particulary in flexion/extension, less pronounced in lateral flexion and axial rotation (p < 0.05). The overall ROM of both tested segments was greatest in lateral flexion, reduced to 52% in flexion/extension and to 16% in axial rotation. After 2 months C2/3- and C4/5-segments with PMMA-fusion and C2/3-segments with Ecopore-interposition showed decrease of ROM in lateral flexion in comparison to the native segments, indicating increasing stiffening. However, after 4 months all operated segments, independent from level or implanted material, were stiffer than the comparable native segments. The decrease of the ROM correlated with the radiological-morphological degree of fusion. Our evaluation of the new porous TiO2/glass composite as interbody fusion cage has shown satisfactory radiological results as well as distinct biomechanical stability and fusion of the segments after 4 months in comparison to PMMA. After histological analysis of the bone-biomaterial-interface, further examinations of this biomaterial previous to an application as alternative to other customary cages in humans are necessary.