Purpose: Adjacent Segment Degeneration (ASD) can occur after spinal fusion. Disc degeneration, spinal stenosis, deformity, spondylolisthesis and fracture are observed. The incidence is unknown and its occurrance difficult to predict. Further major surgery is required to correct the clinical problem that exists although not all cases of ASD are symptomatic. The primary purpose of this study was to identify the incidence of ASD after multilevel(> /=3) thoracolumbar fusions for degenerative disorders. Risk factors for ASD were to be determined. Methods: Over 400 spinal fusions of 3 levels or greater, minimum 5 year follow-up were assessed for ASD. Radiographic data were available from a prospective data bank. The radiological incidence of ASD was distinguished from those that were clinically significant as determined by Oswestry, back and leg pain scores. |Personal and telephone interviews were conducted along with most recent plain xrays. Data was analyzed (ANOVA) from a single surgeon’s practice. Radiographic assessment was performed by the author with radiologist’s opinions available. Results: The incidence of ASD after extended spinal fusions overall was 20%. Clinically significant ASD requiring further surgery was 12%. The incidence varied according to location of the fusion, number of levels, age and preexisting disc degeneration and or deformity at the end vertebrae. Overall it was difficult to predict risk factors but trends were noted. Long fusions(greater than or equal to 3 levels) has a significantly high risk of ASD by 5 yrs after the index operation. Conclusions: The incidence of ASD by 5 years post spine fusion of 3 or more levels is 20% in over 400 cases.12% of these index cases needed further surgery. ASD is a clinically significant entity that deserves study to aid in its prevention

Purpose: Adjacent Segment Degeneration (ASD) can occur after spinal fusion, disc degeneration, spinal stenosis, deformity, spondylolisthesis and fracture. The incidence is unknown and its occurence difficult to predict. Further major surgery is required to correct the clinical problem that exists although not all cases of ASD are symptomatic. The primary purpose of this study was to identify the incidence of ASD after multilevel (> /= 3 level) thoracolumbar fusions for degenerative disorders at a minimum 5 year followup. Risk factors for ASD were to be determined. Method: 405 spinal fusions of three levels or greater, performed between 1988 and 2001, minimum five year followup were assessed for ASD. Radiographic data was available from a prospective data bank. The radiological incidence of ASD was distinguished from those that were clinically significant as determined by Oswestry Disability Index, back and leg pain visual analog scales. Results: The incidence of ASD after extended spinal fusions overall was 28%, based on radiological evaluation. There was an 18% incidence of clinically significant ASD. 10% of the entire group required surgery to address ASD. The incidence varied according to the location of the fusion, number of levels, age and pre-existing disc degeneration and/or deformity at the end vertebrae. Overall it was difficult to predict risk factors but trends were noted. Long fusion (> /= 3 levels) have a significantly high risk of ASD by five years after the index operation. Adjacent level degenerative disc disease and spinal stenosis were the most common type of ASD. Conclusion: The incidence of ASD by five years post spine fusion of three or more levels is 28% in over 405 cases. 10% of these cases needed further surgery. ASD is a clinically significant entity that deserves further study to aid in its prevention

Introduction. The influence of lumbar and lumbosacral fusion on adjacent moving segments has been the subject of a number of studies, which have shown the origin and progress of degenerative changes and instability brought about by alterations of kinematics and elasticity of the fused segment. Back pains which emerge later in the postoperative period may be the consequence of degeneration and instability in the adjacent segment to the said fusion. The fusion shifts the centre of rotation to the level adjacent to the fusion, which increases the pressure and pull on both the disk and joints. It can be supposed that the pull and attendant pains are in direct proportion to the rigidity of the spondylodesis that is more pronounced after anterior intersomatic fusion and less so after posterior. The development of hyperlordosis or kyphosis in the lumbar region is also a risk factor for adjacent segment failure.

Material and methods. The authors performed a retrospective analysis on a group of 91 patients with spondylolisthesis who had undergone PLIF technique with transpedicular fixation surgery and PLF.

A total of 10 (11%) of 91 patients developed symptomatic next segment desease at a previously asymptomatic level. Date were obtained in patients with next – segment failure based on X-rays studies, neurological assessment and sequential follow-up examinations. The aforementioned patients had a mean age of 42.8 years and the mean follow up period was 8.7 years after surgery. 7 cases were isthmic, 2 degenerative and 1 dysplastic spondylolisthesis.

Fusion in every case entailed the use of autologinous bone grafts, and with the PLIF technique cages, in 3 cases, dowels, in 6 cases, and autofibula in 1 case were used. The mean follow-up period between original surgery and next-segment failure was 3.8 years.

Results. In ten cases from the group there was evidence of instability or degeneration, instability in 3 cases (all above fusion) and degeneration in 7 cases (4 above and 3 below fusion) respectively.

All patients with instability in cranial adjacent segment underwent successfully additional surgery by using 360° fusion with instrumentation (ALIF).

Discussion. In X-rays conducted prior to surgery, signs of hypermobility were present in the cranial adjacent segment in one case. This hypermobility affected the rigidity of the fusion in the caudal segment, which accelerated the progress of instability and caused further surgery to be necessary.

The cause of instability could also be overloading of the spine, damage to the stability of ligament and bone structures sustained during the operation, or a combination of the above.

Introduction: We report a series of 10 cases from a cohort of 421 Dynesys procedures in which evidence of Accelerated Adjacent Disc Disease (AASDD).

Spinal fusion for degenerative disc disease is known to have inconsistent outcomes. One concern is the possibility of AASDD as a result of the altered kinematics. The Dynamic Neutralisation System (Dynesys) appears to offer an advantage in that it restricts, rather than abolishes movement at the treated segment, and should thereby reduce the problem of AASDD, In the event of failure, it can in addition be removed, returning the spine to the former status quo. Various biomechanical studies confirmed flexibility of Dynesys.

Method: Ten patients developed new and symptomatic disc disease within segments adjacent to Dynesys. The average age of patients was 49 year with range between 36–70 years. Average post Dynesys to secondary surgery for ASD was 24.7 months. Previous discography and MRI in all cases had shown no evidence of disc disease within these adjacent segements prior to Dynesys. All patients were evaluated preoperatively using Oswestry Disability Index, SF 36 and Visual Analogue Scores together with plain x ray imaging, MRI scanning and discography. Of this cohort Dynesys was indicated to treat single disc level in 7 and two levels in 3

Results: Incidence of AASDD associated with Dynesys was 2.1%. Further surgical intervention included:

Extension of Dynesys10

There was no caudal ASD in our cohort.

Discussion & Conclusions: Dyensys did not prevent the development of accelerated ASD. Evidence from Aylott cadaver studies suggests that Dynesys instrumentation alters the Kinematics of the adjacent segment and increases the excursion. It is unclear whether the small number of AASDD reported here is other than the natural progression of degenerative change. 95.7 cases did not progress.

Background. It has become increasingly important to conduct studies assessing clinical outcomes, reoperation rates, and revision rates to better define the indications and efficacy of lumbar spinal procedures and its association with symptomatic adjacent segment degeneration (sASD). Adjacent segment degeneration (ASD) is defined as the radiographic change in the intervertebral discs adjacent to the surgically treated spinal level. SASD represents adjacent segment degeneration which causes pain or numbness due to post-operative spinal instability or nerve compression at the same level. The most common reason for early reoperation and late operation is sASD, therefore is in our best interest to understand the causes of ASD and make steps to limit the occurrence. Method. A comprehensive literature search was performed selecting Randomized controlled trials (RCTs) and retrospective or prospective studies published up to December 2023. Meta-analysis was performed on 38 studies that met the inclusion criteria and included data of clinical outcomes of patients who had degenerative disc disease, disc herniation, radiculopathy, and spondylolisthesis and underwent lumbar fusion or motion-preservation device surgery; and reported on the prevalence of ASD, sASD, reoperation rate, visual analogue score (VAS), and Oswestry disability index (ODI) improvement. Results. When compared to fusion surgery, a significant reduction of ASD, sASD and reoperation was observed in the cohort of patients that underwent motion-preserving surgery. Conclusion. Dynamic fusion constructs are treatment options that may help to prevent sASD. Conflicts of interest. This research was funded by Paradigm Spine. Sources of funding. Paradigm Spine

Study design: Prospective clinical and radiologic study. Objective: The purpose of this study was to investigate the risk factors for adjacent segment degeneration after posterior lumbar interbody fusion (PLIF). Summary of Background data: Although several authors have reported the adjacent segment degeneration after lumbar or lumosacral fusion, there is no consensus regarding the risk factors for adjacent segment degeneration. Methods: Sixty-five patients were studied after PLIF after a minimum follow up time of 6 years. Plain and flexion/ extension radiographs and MRI scans were obtained and compared to preoperative and postoperative. Progression of segment degeneration was defined as a condition in which the distinction between nucleus and annulus is lost, and the disc space is collapsed according to the grading system (Grade 1–5) described by Pfirrmann et al evaluated with T2 weighted MRI scans. Patients were divided into three groups: Group 1 with no radiological progression of disc degeneration, Group 2 with radiological progression of disc degeneration, and Group 3 with radiological progression of disc degeneration and clinical deterioration. Risk factors for progression of adjacent disc degeneration as lumbar lordosis, lordosis at the fused segment, facet sagittalization, and pre-existing disc degeneration were evaluated. The images were evaluated by two independent radiologists. Results: Fifteen patients (23%) showed no radiological progression of disc degeneration on MRI scans and were classified into Group 1. Forty patients (62%) developed some cranial or caudal deterioration of the adjacent segment without clinical deterioration and were classified into Group 2. Ten patients (15%) required reoperation for neurological and clinical deterioration caused by cranial or caudal degeneration of the adjacent disc (Group 3). No statistically significant differences were found in lumbar lordosis, lordosis at the fused segment, facet sagittalization between each group. Patients in Group 3 showed on preoperative MRI already moderate to severe alteration of the adjacent disc (mean Grade 4) compared to Group 1 (mean Grade 2) and 2 (mean Grade 2,5) (p< 0.01). Conclusion: After PLIF disc degeneration appear homogeneously at several levels cranial and caudal to fusion over the years in most of the patients (79%). Only pre-existing degeneration of the adjacent cranial and caudal segment is a potential risk factor for clinical deterioration caused by disc collapse

The December 2012 Spine Roundup. 360. looks at: the Japanese neck disability index; adjacent segment degeneration; sacroiliac loads determined by limb length discrepancy; whether epidural steroids improve outcome in lumbar disc herniation; spondylodiscitis in infancy; total pedicle screws; and iliac crest autograft complications

Introduction Disc replacement surgery is being investigated as an alternative to spinal fusion surgery in the hope that maintaining segment spinal motion will not only relieve pain, but also prevent or reduce the likelihood of symptomatic adjacent segment degeneration that is believed to be a consequence of fusion surgery. The aim of this study was to identify evidence in the medical literature that indicates whether or not spinal fusion surgery increases the likelihood of symptomatic adjacent segment degeneration compared to disc replacement surgery or natural history. Methods A search of the Cochrane Controlled Trials Register, Medline and reference lists of retrieved articles was performed. Search terms included arthroplasty replacement, spinal fusion, prognosis, controlled clinical trials and cohort studies, Studies were included if abstracts were available electronically, were published in the English language before1/3/2005 and involved humans. Levels of evidence were determined using the Oxford Centre for Evidence-Based Medicine criteria (. http://www.cebm.net/levels of evidence.asp. ). Discussion The majority of identified studies were case series of patients presenting with adjacent level disc degeneration following spinal fusion surgery (Level 4) and whilst indicating patients can develop adjacent level disc degeneration following fusion surgery, do not indicate the likelihood of doing so. Uncontrolled prospective cohort studies (Level 4) provide conflicting evidence. One retrospective cohort (Level 2b) studying comparing the incidence of adjacent disc degeneration following spinal fusion and discectomy or decompressive surgery alone found that the incidence of degeneration in the superior adjacent disc was increased in the fusion group, but was not associated with differences in functional outcome. No systematic reviews of inception cohort studies (Level 1) were identified. Conclusions Only poor quality evidence has been published to support the proposition that spinal fusion surgery is associated with an increased likelihood of developing symptomatic adjacent level disc degeneration. Long term follow-up of patients enrolled in prospective randomised controlled trials comparing outcomes of spinal fusion and disc replacement surgery is necessary to determine whether or not disc replacement surgery decreases the likelihood of any symptomatic adjacent level disc degeneration that can be attributed to spinal fusion surgery

Intervertebral disc (IVD) degeneration plays a major role in low back pain which is the leading cause of disability. Current treatments in severe cases require surgical intervention often leading to adjacent segment degeneration. Injectable hydrogels have received much attention in recent years as scaffolds for seeding cells to replenish disc cellularity and restore disc properties and function. However, they generally present poor mechanical properties. In this study, we investigated several novel thermosensitive chitosan hydrogels for their ability to mimic the mechanical properties of the nucleus pulposus (NP) while being able to sustain the viability of NP cells, and retain proteoglycans. CH hydrogels were prepared by mixing the acidic chitosan solution (2% w/v) with various combinations of three gelling agents: sodium hydrogen carbonate (SHC) and/or beta-glycerophosphate (BGP) and/or phosphate buffer (PB) (either BGP0.4M, SHC0.075M-BGP0.1M, SHC0.075M-PB0.02M or SHC0.075M-PB0.04M). The gelation speed was assessed by following rheological properties within 1h at 37°C (strain 5% and 1Hz). The mechanical properties were characterized and compared with that of human NP tissues. Elastic properties of the hydrogels were studied by evaluating the secant modulus in unconfined compression. Equilibrium modulus was also measured, using an incremental stress-relaxation test 24h after gelation in unconfined compression (5% strain at 5%/s followed by 5min relaxation, five steps). Cells from bovine IVD were encapsulated in CH-based gels and maintained in culture for 14 days. Cytocompatibility was assessed by measuring cell viability, metabolism and DNA content. Glycosaminoglycan (GAG) synthesis (retained in the gel and released) was determined using DMMB assay. Finally injectability was tested using human cadaveric discs. Unconfined compression confirmed drastically enhanced mechanical properties compared to conventional CH-BGP hydrogels (secant Young modulus of 105 kPa for SHC0.075PB0.02 versus 3–6 kPa for BGP0.04). More importantly, SHC0.075PB0.02 and SHC0.075BGP0.1 hydrogels exhibited mechanical properties very similar to NP tissue. For instance, equilibrium modulus was 5.2±0.6 KPa for SHC0.075PB0.02 and 8±0.8 KPa for SHC0.075BGP0.1 compared to 6.1±1.7 KPa for human NP tissue. Rheological properties and gelation time (G′=G″ after less than 15 s at 37°C, and rapid increase of G') of these hydrogels also appear to be adapted to this application. Cell survival was greater than 80% in SHC0.075BGP0.1 and SHC0.075PB0.02 hydrogels. Cells encapsulated in the new formulations also showed significantly higher metabolic activity and DNA content after 14 days of incubation compared to cells encapsulated in BGP0.4 hydrogel. Cells encapsulated in SHC0.075BGP0.1 and SHC0.075PB0.02 produced significantly higher amounts of glycosaminoglycans (GAG) compared to cells encapsulated in SHC0.075PB0.04 and BGP0.4 hydrogels. The total amount of GAG was higher in SHC0.075BGP0.1 hydrogel compared to SHC0.075PB0.02. Interestingly, both the SHC0.075BGP0.1 and SHC0.075PB0.02 hydrogels retained similar amounts of GAG. Injectability through a 25G syringe, filling of nuclear clefts and good retention in human degenerated discs was demonstrated for SHC0.075PB0.02 hydrogel. SHC0.075BGP0.1 appears to be a particularly promising injectable scaffold for IVD repair by providing suitable structural environment for cell survival, ECM production and mechanical properties very similar to that of NP tissue

Background. The controversy concerning the benefits of unisegmental cervical disc arthroplasty (CDA) over anterior cervical discectomy and fusion (ACDF) is still open because some randomised clinical trial (RTC) comparing ACDF with CDA have been highly inconclusive. Most of these studies mixed disc prosthesis with dissimilar kinematic characteristics. To date, a compilation of the clinical and radiologic outcomes and adverse events of anterior cervical discectomy and fusion (ACDF) compared with a single cervical disc arthroplasty (CDA) design, the Bryan disc has partially accomplished. Methods. This is a systematic review of RCTs with level I-II evidence. Only RCTs reporting clinical outcomes were included in this review. After a search on different databases including PubMed, Cochrane Central Register of Controlled Trials, and Ovid MEDLINE, a total of 10 RCTs out of total 51 studies were entered in the study. RTC's were searched from the earliest available records in 2005 to December 2014. Results. Five studies were Level I, and five were Level II. Out of a total of 1101 patients, 562 patients were randomly assigned into the Bryan arthroplasty group and the remaining 539 patients into the ACDF group. The mean follow-up was 30.9 months. Patients undergoing CDA had lower Neck Disability Index, and better SF-36 Physical component scores than ACDF patients. Patients with Bryan CDA had also less radiological degenerative changes at the upper adjacent level. Overall adverse events were twice more frequent in patients with ACDF. The rate of revision surgery including both adjacent and index level were slightly higher in patients with ACDF, showing no statistically significant difference. Conclusions. This review of evidence level I-II RCTs comparing clinical and radiological outcomes of patient undergoing Bryan arthroplasty or ACDF indicated a global superiority of the Bryan disc. The impact of both surgical techniques on the cervical spine (radiological spine deterioration and/or complications) was more severe in patients undergoing ACDF. However, the rate of revision surgeries at any cervical level was equivalent for ACDF and Bryan arthroplasty. These data suggest that even though the loss of motion has a determinant influence in the development of degenerative changes in ACDF cases, these kinematic factors do not imply a higher rate of symptomatic adjacent segment degeneration requiring surgery. Level of Evidence. Level I

Osteoarthritis (OA) is a painful and disabling chronic condition that constitutes a major challenge to health care worldwide. There is currently no cure for OA and the analgesic pharmaceuticals available do not offer adequate and sustained pain relief, often being associated with significant undesirable side effects. Another disease associated with degenerating joints is Intervertebral disc degeneration (IVDD) which is a leading cause of chronic back pain and loss of function. It is characterized by the loss of extracellular matrix, specifically proteoglycan and collagen, tissue dehydration, fissure development and loss of disc height, inflammation, endplate sclerosis, cell death and hyperinnervation of nociceptive nerve fibers. The adult human IVD seems incapable of intrinsic repair and there are currently no proven treatments to prevent, stop or even retard disc degeneration. Fusion is currently the most common surgical treatment of symptomatic disc disease. However, radiographic follow-up studies have revealed that many patients develop adjacent segment disc degeneration due to altered spine biomechanics. The development of safe and efficacious disease modifying OA drugs (DMOADs) that treat pain and inflammation in joints will improve our ability to control the disease. I addition, a biologic treatment of IVDD is desirable. This presentation will provide an overview of recent advances and future prospects of a multimodal biologic treatment of OA, and IVDD. We will focus on Link N, a naturally occurring peptide representing the N terminal region of link protein and the first 1–8 residues of Link N (short Link N, sLN) responsible for the biologic therapy in question

The aim of most new implants for cervical disc replacement is to maintain or restore function. The Dynamic Cervical Implant (DCI(tm), Paradigm Spine) aims at combining the advantages of the gold standard fusion technique with the motion preservation philosophy. DCI has a limited motion: it works like a shock absorbing spring and may help to slow down adjacent segment degeneration. Between 2007 and 2009 we selected 79 patients aged 32 to 73 years for treatment with DCI at either one or two levels (10 patients). Indications were radiculopathies (n=45), axial pain (n=4) or spondylotic spinal stenosis (n=30) with out chronic myelopathy. Patients are followed up at 3, 6, and 12 months after surgery. Disc surgery was performed at C3/C4 (n=2), C4/5 (n=6), at C5/6 (n=43), C6/7 (n=37) and at C7/T1 (n=1). In flexion/extension radiographs motion rapidly increased after surgery. However, 5 of 19 treated levels were fused (seen at 6 or 12 months). After implant footprint was changed and larger sizes were provided only 2 of 67 segments fused. Still 96% of the patients rated their clinical result as excellent or good. There were no implant related complications or revision surgery. Disc replacement with DCI is a new strategy that is positioned in between anterior cervical fusion and disc prosthesis. Clinical results are as good as in anterior cervical fusion. Adjacent segment protection must be judged in future follow-ups. We were able to show that the change of implant footprint has significantly reduced fusion rate

Lumbar Total Disc Replacement (LTDR) is an alternative to fusion for the surgical management of discogenic back pain not responding to conservative therapy. Theoretical advantages include preservation of motion and possible reduction in adjacent segment degeneration. The aim is to review the early results of LTDR in an Auckland private practice. A prospective study was carried out on 32 consecutive patients treated with LTDR. Discogenic back pain was confirmed with plain radiographs, MRI and CT lumbar discogram. The Charité TDR was used in 19 patients and A-MAV in 13. Follow-up was to a minimum of two years. Patients completed Modified Roland Questionnaires (MRQ), Visual Analogue Pain Scores (VAPS) and Lower Back Outcome Scores (LBOS) pre and post-operatively. Patients’ notes and radiographs were reviewed. All outcomes measures improved significantly. Mean MRQ scores improved from 14.2 to 6.4 and 4.8 (at one and two years respectively). Mean VAPS improved from 5.3 to 2.5 and 1.7. Mean LBOS improved from 33 to 52 and 57. 84% had radiographic evidence of motion at the level of the prosthesis. There were four major complications. A retroperitoneal haematoma, an incisional hernia, a ureteric stenosis and subsidence of the prosthesis each occurred in separate patients. These all occurred in the first ten patients of the study and were related to the approach. There were no major thrombo-embolic or infective complications and no revision surgery was required. LTDR is a safe and effective surgical treatment of discogenic back pain. There is however, a steep learning curve with regard to the approach and a higher risk of complications during this time. Initial results are encouraging, but longer term follow-up needs to be performed

Neck pain can be caused by pressure on the spinal cord or nerve roots from bone or disc impingement. This can be treated by surgically decompressing the cervical spine, which involves excising the bone or disc that is impinging on the nerves or widening the spinal canal or neural foramen. Conventional practise is to fuse the adjacent intervertebral joint after surgery to prevent intervertebral motion and subsequent recompression of the spinal cord or nerve root. However fusion procedures cause physiological stress transfer to adjacent segments which may cause Adjacent Segment Degeneration (ASD), a rapid degeneration of the adjacent discs due to increased stress. ASD is more likely to occur in fusions of two or more levels than single level fusions and is more common where there is existing degeneration of the adjacent discs, which is not unusual in people over 30 years of age. Partial dynamic stabilisation, which generally involves a semi-rigid spinal fixation, allows a controlled amount of intervertebral motion (less than physiological, but more than fusion) to prevent increased stress on the adjacent segments (potentially preventing ASD) whilst still preventing neural recompression. Partial dynamic stabilisation is suitable for treating spinal instability after decompression as well as certain degenerative instabilities and chronic pain syndromes. Dynamic stabilisation and semi-rigid fixation systems for the spine are typically fixated posteriorly. However, choice of posterior surgical stabilisation techniques in the cervical spine is limited due to the size of the osseous material available for fixation and the close proximity of the neural structures and the vertebral artery. Posterior dynamic stabilisation systems for stabilisation of the lumbar spine often use the pedicle as an anchor point. Using the pedicle of the cervical spine as an anchor point is technically difficult because of its small size, angulation and proximity to neurovascular structures. Therefore, one of the main challenges to provide stabilisation in the cervical spine is the limitations of the anatomy. This presentation will introduce a novel spinal implant (patent pending) which is proposed for the cervical spine to provide partial dynamic stabilisation in the C3 to T1 region from a posterior approach. The implant is a single unit with a safe and technically simple insertion technique into the lateral masses. The implant uses a simple mechanism to allow limited intervertebral motion at each instrumented level. It is hoped that the simplicity of the device and removing the need to provide a bone graft anteriorly may reduce the cost of the procedure compared to traditional fusion and competing surgeries

Anterior cervical discectomy and fusion for radiculopathy and myelopathy has the complication of the development of adjacent segment degeneration. Furthermore, reoperations may be required to treat complications of fusion, such as non-union, graft collapse, or expulsion. Cervical disc arthroplasty lays claim to preserving cervical motion and reducing the risks of adjacent segment disease in the treatment of cervical radiculopathy. We performed a prospective study in order to evaluate the radiological and clinical outcomes of cervical disc arthroplasty for single or two level disc disease with associated radiculopathy. Our study included a total of 26 patients. Each patient had cervical radiculopathy from nerve root compression due to degenerative disc disease at one or two levels. Diagnosis was made preoperatively on clinical examination and by means of MRI scanning. Each patient also had preoperative flexion and extension cervical spine x-rays in order to assess pre-operative range of neck movement. The outcomes of surgery were assessed prospectively. Range of motion at final follow-up was measured by flexion and extension view x-rays of the cervical spine. Clinical outcome was assessed by means of VAS scores for pain, SF12 for mental and physical health and the neck disability index (NDI). All complications were recorded. 14 of the patients had a follow-up for two years and the remaining 12 patients had a follow-up for one year. A Discovery disc arthoplasty by Scient'X was the implant used in all patients. A standard anterior cervical approach was used to achieve decompression and for the implantation of the prosthesis. On follow-up all patients had either maintenance or an improvement in the range of movement. There was no evidence of progression of degeneration in the segments adjacent to the arthroplasty prosthesis. Improvements in SF12, VAS, and NDI scores were seen from preoperative levels in 25 of the 26 patients. Complications included one patient with a horse voice post-operatively and one patient with minimal improvement of radicular symptoms. Post-operative MRI scanning demonstrated adequate decompression with this procedure and showed no evidence of progression of adjacent segment disease. There were no cases of implant subsidence or dislocations. We have found cervical disc arthroplasty to produce good clinical outcomes when used for single or two level cervical radiculopathy whilst maintaining neck motion with an acceptable complication rate. A longer follow-up is needed to further assess the risk of development of adjacent segment disease but we did not discover the development of adjacent segment disease in our study with a follow-up of upto 2 years

Introduction: Disc Replacement has been described as 21st Century revolution in spinal surgery that preserves mobility and prevents adjacent segment degeneration. Numerous short-term studies are available on clinical outcome but to date there are no published long term clinical, radiological and survival data on disc replacement. Aim: To analyse clinical, radiological & survival results of Charite III Disc Replacement. Study Design: Ethical committee approved retrospective study. Methodology: 160 patients (Av. Age 46yrs; Std.Dev 8.06; 62 Males & 98 Females) underwent disc replacement surgery between Jan1990 and Dec2000. An independent observer reviewed case notes, radiographs and administered a questionnaire that included Oswestry Disability Index, and Pain Score. Results: Clinical: At an average follow up of 79 (range 31 to 161) months, mean improvement in ODI and pain score were 18.01(p< 0.001) and 1.69(p< 0.001) respectively. Radiological: average movement at replaced disc, defined as greater than 4 degrees on flexion-extension lateral view was 1.5 degrees for L3L4, 4.01 degrees for L4L5 and 4.8 degrees for L5S1 disc replacement. Survival: A mean survival time of 147(95% C.I. 140 to 154) months was observed with cumulative survival of 55% with implant removal as an endpoint. A mean survival time of 124(95% C.I. 116 to 133) months with cumulative survival of 35% was observed with all radiological failures as an endpoint. Complications: were post-operative incisional hernia seen in 17(10.6%), wound infection 9(5.6%) and retrograde ejaculation in 5(3.1%) patients. Conclusion: Charite III Disc Replacement results in clinically significant (> 15, p< 0.001) improvement in ODI, but does not result in clinical significant (> 2 points) improvement in back pain. Motion is preserved at L4L5 and L5S1 level. It has low survival rate and does not seem to prevent onset of facet arthritis. This study does not support the use of this device for management of back pain

Introduction. The degeneration of the adjacent segment in lumbar spine with spondylodesis is well known, though the exact incidence and the mechanism is not clear. Several implants with semi rigid or dynamic behavior are available to reduce the biomechanical loads and to prevent an adjacent segment disease (ASD). Randomized controlled trials are not published. We investigated the biomechanical influence of dynamic and semi rigid implants on the adjacent segment in cadaver lumbar spine with monosegmental fusion (MF). Materials and Methods. 14 fresh cadaver lumbar spines were prepared; capsules and ligaments were kept intact. Pure rotanional moments of ±7.5 Nm were applied with a Zwick 1456 universal testing machine without preload in lateral bending and flexion/extension. The intradiscal pressure (IDP) and the range of motion (ROM) were measured in the segments L2/3 and L3/4 in following situations: in the native spine, monosegmental fusion L4/5 (MF), MF with dynamic rod to L3/4 (Dynabolt), MF with interspinous implant L3/4 (Coflex), and semi rigid fusion with PEEK rod (CD Horizon Legacy) L3-L5. Results. Under flexion load all implants reduced the IDP of segment L2/L3, whereas the IDP in the segment L3/4 was increased using interspinous implants in comparison to the other groups. The IDP was reduced in extension in both segments for all semi rigid or dynamic implants. Compared under extension to the native spine the MF had no influence on the IDP of the adjacent disc. The rod instrumentation (Dynabolt, PEEK rod) lead to a decreased IDP in lateral bending tests. The ROM in L3 was reduced in all groups compared to the native spine. The dynamic and semi rigid stabilization in the segment L3/4 limited the ROM more than the MF. Discussion. The MF reduced the ROM in all directions, whereas the IDP of the adjacent segment remained unaffected. The support of the adjacent segment by semi rigid and dynamic implants decreased the IDP of both segments in extension mainly. This fact is an agreement with other studies. Compared to our data, no significant effect on the adjacent levels was observed. Interestingly, in our study, the IDP of the adjacent segment is unaffected by MF. The biomechanical influence in the view of an ASD could be comprehended, but is not completely clear. The fact of persistent IDP in the adjacent segment suggests that MF has a lower effect on the adjacent segment degeneration as presumed. Biomechanical studies with human cadaver lumbar spines are limited and depend on age and degenerative situation. The effect on supporting implants on adjacent segment disease in lumbar spine surgery has to be investigated in clinical long term studies

Anterior decompression and fusion has been standard treatment for cervical disc herniation and myelopathy with disc degeneration. Since cervical total disc replacement (TDR) has been introduced with early favorable results and ideal mechanism, it has gained its popularity recently. But varying degrees of heterotopic ossification (HO) around the operated segment have been noted in the literatures. The theoretical advantages of TDR are the maintenance of intervertebral motion and prevention of adjacent segment degeneration. It is questionable that if HO occurs after TDR, mobility of operated segments would be restricted then clinical outcome worse. Purpose of this study is to determine prevalence of HO and to investigate that the presence of HO would limit motion and subsequently negatively affect clinical outcome following cervical TDR. We analyzed 29 patients (30 levels) who were treated with cervical TDR by 2 spine specialists using 4 types of prostheses (Mobi-C: 13 levels, ProDisc: 10, Bryan: 5, Prestige LP: 2) consecutively from July 2004 to June 2007. Postoperative mean follow-up period was 21.4 (12–36) months. We assessed presence of HO and segmental ROM radiographically and clinical outcome by VAS, ODI after 1.5, 3, 6 months, and every year postoperatively in principle. All subjects were divided by 3, which were group A (no HO, McAfee class 0), group B (class I and II), and group C (class III and IV), then compared with each other. HO was detected on 14 levels (46.7%) in the 30 levels after at mean of 8.2 (4–18) months after operation. There were 15 levels(53.3%) of group A (no HO, class 0), 7 levels of group B (class I HO:3, II: 4), and 7 levels of group C (class III: 3, IV: 4). Segmental flexion-extension ROM of group A was 10.1 (5.6–16.2)°, group B is 8.3 (3.5–14.4)°, and group C is 3.1 (0.0–6.6)° (p< 0.001, multiple comparison test with post hoc Bonferroni correction). And no difference in the clinical outcomes, VAS and ODI, was found compared with each other among group A, B, and C (p> 0.05). Nonetheless, longer term follow-up should be performed to investigate whether clinical outcomes would be changed and occur adjacent level degeneration as time goes on. In addition, further study for prevention of HO may be needed as in HO of other joint replacement surgery not to lose superior mechanism to fusion treatment

INTRODUCTION:. As a consequence from cervical arthroplasty, spine structural stiffness, loading and kinematics are changed, resulting in issues like adjacent segment degeneration and altered range of motion. However, complex anatomical structures and lack of adequate precision to study the facet joint (FJ) segmental motion in 3D have prevented proper quantitative analyses. In the current study, we investigate the innovative use of a local coordinate system on the surface of the superior articular process of the caudal vertebral body in order to analyze FJ segmental motion using CT-based 3D vertebral models in flexion/extension. METHODS:. CT images were obtained from six patients (2F/4M, mean age: 53 y.o.) with cervical degenerative disc disease in neutral, flexion and extension positions. CT data was used to create subject-specific surface mesh models of each vertebral body. From these, mean normal vectors were calculated for all FJ surfaces and posterior walls from C3/4 down to C6/7 (Fig. 1). The global coordinate system (x, y, z) corresponds to the CT scanner. Within this system, a new local coordinate system (u, v, w) was set on the centroid of each FJ surface (Fig. 1), where the u-, v-, and w- axes correspond to the normal-to-the-FJ, right-left and cranio-caudal directions, respectively. In flexion/extension, translations in mm were calculated as differences in the FJ centroid position and rotations were calculated in degrees as angular differences of the vector of the opposing surface in flexion/extension. Results are presented as mean ± SD. Differences within vertebral levels and left/right FJs were sought using 1- or 2-way ANOVA, respectively. RESULTS:. The flexion/extension segmental motion was described in its six degrees-of-freedom. Among the three translations, the largest movement was observed in the cranio-caudal direction (u = −0.22 ± 0.47 mm, v = 0.11 ± 0.89 mm, w = −2.06 ± 1.60 mm); while the three rotations about the (u, v, w) axes showed a dominant rotation about the v-axis (u = −0.41 ± 4.42°, v = −5.12 ± 5.61°, w = −0.01 ± 2.71°). Comparing translational and rotational motions by cervical level, movements at C6/7 were shown to be smaller than those at the other levels (p < 0.05) (Figs. 2, 3). There were no significant differences in the movement of the FJ between left and right sides (p > 0.05). DISCUSSION:. A key finding of this study was that along with the expected translation in the w-axis, there was rotation about the v-axis consistent with the overall neck flexion-to-extension motion. If the rotation about the v-axes were negligible, the FJ motion could be considered as a pure translation (sliding), but the data suggests otherwise. This finding supports the hypothesis of a rolling-sliding type of facet segmental motion that might be influenced by the facet surface curvature. Future studies will focus on analyses of the changes in FJ gap with motion and characterization of the facet surfaces' curvature and congruence. SIGNIFICANCE: An innovative look into flexion/extension motion from the FJ point of view describes FJ segmental motion as a sliding-rolling motion instead of the traditional concept of sliding-only mechanism

Introduction: Surgical management of discogenic low back pain has in the past been limited to spinal fusion. Recently disc arthroplasty has become available. The rationale for disc arthroplasty is that it may avoid the long term consequences of adjacent segment degeneration. Avoidance of long term consequences is of no value unless the short term outcome is at least equivalent between fusion and arthroplasty. Methods: A series of patients with chronic low back pain with concordant lumbar discography and a negative control discogram were surgically treated. Prospective data was collected preoperatively and at regular intervals during the post-operative period for a historical series of combined anterior and posterior lumbar fusion (n =24), a series of SB Charité (DePuy Spine) disc replacements (n =23), and recently, a series of Maverick (Medtronic Sofamor Danek) artificial disc replacements (n =9). Self assessed outcome measures of visual analog pain score (VAS), Low Back Outcome Score (LBOS) and SF12 general health data was obtained at intervals after the surgery. This paper presents the results of the consecutive series that have a minimum of 3 months follow-up. Results: The data for the two groups of arthroplasty was combined and compared to the fusion group. The mean age for the fusion group was 37.6 years and the mean age for the arthroplasty group was 38.6 years. There were 5 compensation cases (20.8 %) in the fusion group and 5 cases (15.6 %) in the arthroplasty group. Both groups had 69% male patients. The mean VAS dropped from 7.5 to 3.7 (p< 0.001) in the arthroplasty group and from 7.3 to 3.5 (p< 0.001) in the fusion group. The mean LBOS improved from 22.0 to 36.5 (p< 0.001) in the arthroplasty group and from 19.6 to 37.1 (p< 0.001) in the fusion group. There was no apparent difference between the clinical improvement in VAS and LBOS (p=0.91 and p=0.45 respectively) for each group. Analysis of the power of the comparison showed an 86% power for comparison of VAS improvement using a clinically important difference (delta) of 1 VAS point and there was 98% power for the LBOS improvement comparison using a clinically important difference (delta) of 10 LBOS points. Complications appeared higher in the arthroplasty group with foraminal encroachment requiring revision in 3 cases and one case of polyethylene failure in the Charité group at 3 years. This case occurred with an 8mm polyethylene insert (since removed from inventory by the manufacturer). Discussion: Disc arthroplasty in the lumbar spine appears to offer similar short term results to that of fusion for chronic low back pain. The surgical complication rate may be higher in the early learning curve of the procedure