Introduction. Anterior cervical decompression and fusion (ACDF) is considered a standard surgical treatment to degenerative discogenic diseases. Lately, the question arises whether or not ACDF significantly influences the progression of adjacent disc degeneration (ADD). The etiology of ADD is obscure and it has not been fully understood whether ADD is a consequence of fusion or it represents the aging pathway of the degenerative cervical process, thus making it a controversial topic [1-3]. There have been several discussions about the possibility of ACDF altering biomechanical conditions at adjacent segments, therefore resulting in increased load and excessive motion [3,4]. The purpose of this study was to compare the cervical segmental motion pre- and post-ACDF using novel 3D analytical techniques. Methods. Nine patients (2F/7M, mean age: 54.1 years, range 36–76 y.o.) underwent ACDF due to symptomatic cervical degenerative discogenic disease. One-level ACDF was performed in 4 patients, whereas 2-level ACDF was done in five, using cylindrical titanium porous cage implants. Pre- and post (postoperative periods ranged from 11-months, 25 days to 12-months, 22 days, mean postoperative period: 12.09 months) surgery, dynamic-CT examinations were conducted in neutral, flexion and extension positions. Subject-based 3D CT models were created for segmental motion analysis (Fig. 1). Six-degrees-of-freedom 3D segmental movements were analyzed using a validated Volume-Merge methods (accuracy: 0.1 mm in translation, 0.2°in rotation) [5]. The segmental translation was evaluated by the segmental translations of gravity centers of endplates (Fig. 2). Disc-height distribution was measured using a custom-written Visual C++ routine implementing a lease-distance calculation algorithm. The mean translation distance was calculated for the each adjacent level (Fig. 2). Differences of segmental motions and mean disc height between pre- and post-surgery at each level were compared by the Wilcoxon signed rank test. Results were presented mean±SEM. Results. Regarding the fusion level, the data shows decreases in both the flexion/extension (F/E) angular range of motion (ROM) (7.46±1.17°preoperatively vs. 3.14±0.56°post-operatively, p<0.003) and the segmental translation in the anterior/posterior direction (AP translation) after surgery (1.22±0.20 mm pre-operatively and 0.32±0.11 mm post-operatively, p<0.01). For the adjacent levels category (inferior and superior combined), the E/F angular ROM was larger after surgery (6.74±1.22°pre-operatively vs. 8.48±0.56°post-operatively, p<0.03). The lateral and axial rotational angular ranges of motion pre- and post-surgery did not show any statistically differences at the adjacent levels. The AP translation at the adjacent levels did not change after surgery (1.22±0.26 mm pre-operatively and 1.45±0.29 mm post-operatively). Translations in lateral and cranio-caudal directions also did not show change following surgery. The mean disc height in the adjacent level (2.39±0.14 mm) showed no differences with respect to the post-surgical measurements (2.40±0.19 mm). Conclusions. The use of a high-accuracy in vivo 3D kinematic analysis method enabled the detection of subtle changes in segmental movement between pre- and post-ACDF conditions. The result of the current study showed increased segmental movements in F/E angles at the adjacent level. These results are consistent with the some previous studies in the literature [4,6-11]. The magnitude of the increased movement, however, was only 1.74°from full-full-flexion to full-extension and no increase was found in AP translation. No disc height loss associated with disc degeneration was observed during a 1-year period after ACDF. Longer follow-up studies with larger patient cohorts will be required to investigate whether the increased F/E angle at the adjacent level effectively causes symptomatic ADD

The primary objective is to compare revision rates for lumbar disc replacement (LDR) and fusion at the same or adjacent levels in Ontario, Canada. The secondary objectives include acute complications during hospitalization and in 30 days, and length of hospital stay. A population-based cohort study was conducted using health administrative databases including patients undergoing LDR or single level fusion between October 2005 to March 2018. Patients receiving LDR or fusion were identified using physician claims recorded in the Ontario Health Insurance Program database. Additional details of surgical procedure were obtained from the Canadian Institute for Health Information hospital discharge abstract. Primary outcome measured was presence of revision surgery in the lumbar spine defined as operation greater than 30 days from index procedure. Secondary outcomes were immediate/ acute complications within the first 30 days of index operation. A total of 42,024 patients were included. Mean follow up in the LDR and fusion groups were 2943 and 2301 days, respectively. The rates of revision surgery at the same or adjacent levels were 4.7% in the LDR group and 11.1% in the fusion group (P=.003). Multivariate analysis identified risk factors for revision surgery as being female, hypertension, and lower surgeon volume. More patients in the fusion group had dural tears (p<.001), while the LDR group had more “other” complications (p=.037). The LDR group had a longer mean hospital stay (p=.018). In this study population, the LDR group had lower rates of revision compared to the fusion group. Caution is needed in concluding its significance due to lack of clinical variables and possible differences in indications between LDR and posterior decompression and fusion

Cervical spinal arthrodesis is the standard of care for the treatment of spinal diseases induced neck pain. However, adjacent segment disease (ASD) is the primary postoperative complication, which draws great concerns. At present, controversy still exists for the etiology of ASD. Knowledge of cervical spinal loading pattern after cervical spinal arthrodesis is proposed to be the key to answer these questions. Musculoskeletal (MSK) multi-body dynamics (MBD) models have an opportunity to obtain spinal loading that is very difficult to directly measure in vivo. In present study, a previously validated cervical spine MSK MBD model was developed for simulating cervical spine after single-level anterior arthrodesis at C5-C6 disc level. In this cervical spine model, postoperative sagittal alignment and spine rhythms of each disc level, different from normal healthy subject, were both taken into account. Moreover, the biomechanical properties of facet joints of adjacent levels after anterior arthrodesis were modified according to the experimental results. Dynamic full range of motion (ROM) flexion/extension simulation was performed, where the motion data after arthrodesis was derived from published in-vivo kinematic observations. Meanwhile, the full ROM flexion/extension of normal subject was also simulated by the generic cervical spine model for comparative purpose. The intervertebral compressive and shear forces and loading-sharing distribution (the proportions of intervertebral compressive and shear force and facet joint force) at adjacent levels (C3-C4, C4-C5 and C6-C7 disc levels) were then predicted. By comparison, arthrodesis led to a significant increase of adjacent intervertebral compressive force during the head extension movement. Postoperative intervertebral compressive forces at adjacent levels increased by approximate 20% at the later stage of the head extension movement. However, there was no obvious alteration in adjacent intervertebral compressive force, during the head flexion movement. For the intervertebral shear forces in the anterior-posterior direction, no significant differences were found between the arthrodesis subject and normal subject, during the head flexion/extension movement. Meanwhile, cervical spinal loading-sharing distribution after anterior arthrodesis was altered compared with the normal subject's distribution, during the head extension movement. In the postoperative loading-sharing distribution, the percentage of intervertebral disc forces was further increased as the motion angle increased, compared with normal subject. In conclusion, cervical spinal loading after anterior arthrodesis was significantly increased at adjacent levels, during the head extension movement. Cervical spine musculoskeletal MBD model provides an attempt to comprehend postoperative ASD after anterior arthrodesis from a biomechanical perspective

Low back pain is the single most common cause for disability in individuals aged 45 years or younger, it carries tremendous weight in socioeconomic considerations. Degenerative aging of the structural components of the spine can be associated with genetic aspects, lifetime of tissue exposure to mechanical stress & loads and environmental factors. Mechanical consequences of the disc degenerative include loss of disc height, segment instability and increase the load on facets joints. All these can lead to degenerative changes and osteophytes that can narrow the spinal canal. Surgery is indicated in patients with spinal stenosis who have intractable pain, altered quality of life, substantially diminished functional capacity, failed non-surgical treatment and are not candidates for non-surgical treatment. The aim was to determine the reasons for refusal of surgery in patients with established degenerative lumber spine pathology eligible for surgery. All patients meeting the study criteria, patients older than 18 years, patients with both clinical and radiological established symptomatic degenerative lumbar spine pathology and patients eligible for surgery but refusing it were recruited. Questionnaire used to investigate reasons why they are refusing surgery. Results 59 were recruited, fifty-one (86.4 %) females and eight (13.6 %) males. Twenty (33.8 %) were between the age of 51 and 60 years, followed by nineteen (32.2 %) between 61 and 70 years, and fourteen (23.7 %) between 71 and 80 years. 43 (72 %) patients had lumber spondylosis complicated by lumber spine stenosis, followed by nine (15.2 %) with lumbar spine spondylolisthesis and four (6.7 %) had adjacent level disease. 28 (47.4 %) were scared of surgery, fifteen (25.4 %) claimed that they are too old for surgery and nine (15.2 %) were not ready. Findings from this study outlined that patients lack information about the spinal surgery. Patients education about spine surgery is needed

INTRODUCTION. Several clinical studies demonstrated long-term adjacent-level effects after implantation of spinal fusion devices[1]. These effects have been reported as adjacent joint degeneration and the development of new symptoms correlating with adjacent segment degeneration[2] and the trend has therefore gone to motion preservation devices; however, these effects have not been understood very well and have not been investigated thoroughly[3]. The aim of this study is to investigate the effect of varying the stiffness of spinal fusion devices on the adjacent vertebral levels. Disc forces, moments and facet joint forces were analyzed. METHODS. The AnyBody Modeling System was used to compute the in-vivo muscle and joint reaction forces of a musculoskeletal model. The full body model used in this study consists of 188 muscle fascicles in the lumbar spine and more than 1000 individual muscle branches in total. The model has been proposed by de Zee et al.[3], validated by Rasmussen et al.[4] and by Galibarov et al.[5]. The new model[5] determines the individual motions between vertebrae based on the equilibrium between forces acting on the vertebrae from muscles and joints and the passive stiffness in disks and ligaments, figure 1a. An adult of 1.75 m and 75 kg with a spinal implant in L4L5 was modeled. This model was subjected to a flexion-extension motion using different elastic moduli to analyze and compare to a non-implanted scenario. The analyzed variables were vertebral motion, the disc reaction forces and moments, as well as facet joint forces in the treated and the adjacent levels: L2L3, L3L4, L4L5 and L5-Sacrum. RESULTS. When introducing a spinal fusion device in the L4L5 joint the reaction forces and moments decreased in this joint with stiffer devices leading to lower joint loads. However, in the adjacent joints, L3L4 and L5Sacrum, an increase was observed when implanting stiffer devices. Similar trends could be found for the L2L3 joint. The loads in the facet joints showed the same trends. While introducing a spinal fusion device reduced the facet joint forces in the treated joint, the loads in the adjacent facet joints were increased according to the stiffness of the implanted device, figure 1b. DISCUSSION. While the treated disc joint showed reduced motion and loads, the adjacent levels demonstrated a significant increase. In particular, the increased facet joint forces in the adjacent levels can lead to adjacent level facet pain or accelerated facet joint degeneration. Introducing a device resulted in preventing facet contact and therefore facet joint loads, even using the device with the lowest stiffness. CONCLUSION. The presented model shows that clinical complications such as facet joint degeneration in adjacent levels after implantation of spinal fusion device are consistent with the change in the mechanical-stimulus distribution in the system

Introduction. The ESP prosthesis is a one-piece deformable but cohesive interbody spacer. it provides 6 full degrees of freedom about the 3 axes including shock absorption (fig1). The prosthesis geometry allows limited rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The rotation center can vary freely during motion in this “silentblock” implant. It thus differs substantially from current prostheses. Material and methods. Surgeries were performed by 2 senior surgeons in 54 women and 34 men (1level in 72 cases, 2 levels in 3 cases, hybrid construct in 13 cases). Average age was 42 (SD: 7). Average BMI was 24.2kg/m2 (SD: 3,4). Clinical data and X-rays were collected at the preoperative time and at 3, 6, 12, 24, and 60 months post-op. The analysis was performed by a single observer independent from the selection of patients and from the surgical procedure. The radiological analysis at 60 months follow-up could be realized in only 76 cases because the quality of the dynamic Xrays was not sufficient in 12 patients. We measured the ROM and the location of mean center of rotation (MCR) of the implanted and adjacent levels using the Spineview® software. The MCR is considered to reflect the quality of movement of a segment; it is localized thanks its co-ordinates. X is expressed as a percentage of the length of the vertebral end plate, and Y as a percentage of the height of the posterior wall. The usual location of the MCR is in a circle, whose center is placed between 30 and 50% of the superior vertebral endplate of the vertebra below, and whose diameter is 70% of the vertebral endplate size. Results. We did not observe device-related complications. All clinical outcomes significantly improved when compared to the pre-operative status (table 1, table 2). Mean ROM was 6,3° (SD 3,2) at the implanted level, 6,7°(5,2) at the above level, 7°(4,9) at the below level. Mean x-MCR value at the implanted level was 33.1% ± 20.8 % and mean y-MCR value −12,41% ± 30.1%. Mean x- MCR value at the above adjacent level was 25,7% ± 30.1% and mean y-MCR value 16%± 39.4%. Mean x- MCR value at the below adjacent level were 31.1% ± 29.8 % and mean y-MCR value − 0,61% ± 46.8. Conclusion. The concept of the viscoelastic ESP prosthesis is different from that of the “first generation” disc implants. This study reports encouraging clinical results about pain, function, and radiological kinematic behavior especially because the MCR appears similar to those of the natural disc described in the literature. The adaptation ability is one of the main feature of this concept as we need to consider the long term evolution of the global posture and mobility after disc replacement. For figures/tables, please contact authors directly.

INTRODUCTION. Lumbar total disc replacement (TDR) is an alternative treatment to avoid fusion related adverse events, specifically adjacent segment disease. New generation of elastomeric non-articulating devices have been developed to more effectively replicate the shock absorption and flexural stiffness of native disc. This study reports 5 years clinical and radiographic outcomes, range of motion and position of the center of rotation after a viscoelastic TDR. Material and methods. This prospective observational cohort study included 61 consecutive patients with monosegmental TDR. We selected patients with intermediate functional activity according to Baecke score. Hybrid constructs had been excluded. Only cases with complete clinical and radiological follow-up at 3, 6, 12, 24 and 60 months were included. Mean age at the time of surgery was 42.8 +7.7 years-old (27–60) and mean BMI was 24.2 kg/m² +3.4 (18–33). TDR level was L5-S1 in 39 cases and L4-L5 in 22 cases. The clinical evaluation was based on Visual Analog Scale (VAS) for pain, Oswestry Disability Index (ODI) score, Short Form-36 (SF36) including physical component summary (PCS) and mental component summary (MCS) and General Health Questionnaire GHQ28. The radiological outcomes were range of motion and position of the center of rotation at the index and the adjacent levels and the adjacent disc height changes. Results. There was a significant improvement in VAS (3.3±2.5 versus 6.6±1.7, p<0.001), in ODI (20±17.9 versus 51.2±14.6, p<0.001), GHQ28 (52.6±15.5 versus 64.2±15.6, p<0.001), SF 36 PCS (58.8±4.8 versus 32.4±3.4, p<0.001) and SF 36 MCS(60.7±6 versus 42.3±3.4, p<0.001). Additional surgeries were performed in 5 cases. 3 additional procedures were initially planified in the surgical program: one adjacent L3-L5 ligamentoplasty above a L5S1 TDR and two L5S1 TDR cases had additional laminectomies. Fusion at the index level was secondary performed in 2 L4L5 TDR cases but the secondary posterior fusion did not bring improvement. In the 56 remaining patients none experienced facet joint pain. One patient with sacroiliac pain needed local injections. Radiological outcomes were studied on 56 cases (exclusion of 5 cases with additional surgeries). The mean location centers of the index level and adjacent discs were comparable to those previously published in asymptomatic patients. According to the definition of Ziegler, all of our cases remained grade 0 for disc height (within 25% of normal). Discussion. The silent block design of LP-ESP provides an interesting specificity. It could be the key factor that makes the difference regarding facets problems and instability reported with other implants experimentally or clinically. Unfortunately no other comparative TDR series are available yet in the literature. Conclusion. This series reports significant improvement in mid-term follow up after TDR which is consistent with previously published studies but with a lower rate of revision surgery and no adjacent level disease pathologies. The radiographic assessment of the patients demonstrated the quality of functional reconstruction of the lumbar spine after LP ESP viscoelastic disc replacement

PEEK rods construct has been proposed to allow better load sharing among spinal components when compared to the more traditional Titanium rods constructs. However, such proposal has largely derived from single-load in-vitro testing and the biomechanical differences between the two constructs when subjected to fatigue loading remain unknown. Current study comparatively analyzed the in-vitro biomechanical performance of PEEK and Titanium rod constructs as spinal implants through a 5 hour fatigue loading test. The disc height and intradiscal pressure of the instrumented and adjacent levels pre- and post-loading were recorded for analysis. The stress levels on the rods and bone stress near the screw-bone interface were also collected to investigate the likely failure rates of the two constructs. The results showed that the Titanium rods construct demonstrated a minimum amount of loss of disc height and intradiscal pressure at the instrumented level, however, a significant loss of the disc height and intradiscal pressure at adjacent levels compared to the intact spine were identified. In contrast, the disc height and intradiscal pressure of the PEEK rods were found to be comparable to those of the intact spine for all levels. The PEEK rods group also showed significantly less bone stress near the screw-bone interface compared to the Titanium rods group. Current study has demonstrated the potential benefits of the PEEK rods construct in reducing the risks of adjacent segment disease and implant failure rates when compared to the more traditional Titanium rods construct

Introduction. Total disc replacement (TDR) provides an alternative to fusion that is designed to preserve motion at the treated level and restore disc height. The effects of TDR on spine biomechanics at the treated and adjacent levels are not fully understood. Thus, the present study investigated facet changes in contact pressure, peak contact pressure, force, peak force, and contact area at the facet joints after TDR. Methods. Seven fresh-frozen human cadaveric lumbar spines were potted at T12 and L5 and installed in a 6-DOF displacement-controlled testing system. Displacements of 15° flexion/extension, 10° right/left bending, and 10° right/left axial rotation were applied. Contact pressure, peak contact pressure, force, peak force and contact area for each facet joint were recorded at L2-L3 and L3-L4 before and after TDR at L3-L4 (ProDisc-L, Synthes Spine). The data were analysed with ANOVAs/t-tests. Results. Axial rotation had the most impact on contact pressure, peak contact pressure, force, peak force, and contact area in intact spines. During lateral bending and axial rotation, TDR resulted in a significant increase in facet forces at the level of treatment and a decrease in contact pressure, peak contact pressure, and peak force at the level superior to the TDR. With flexion/extension, there was a decrease in peak contact pressure and peak contact force at the superior level. Conclusion. Our study demonstrates that rotation is the most demanding motion for the spine. We also found an increase in facet forces at the treated level after TDR. To our knowledge, we are the first to show a decrease in several biomechanical parameters after TDR at the adjacent superior level in a cadaveric model. In general, our findings suggest there is an increase in loading of the facet joints at the level of disc implantation and an overall unloading effect at the level above

Purpose of Study. Debate exists in the literature about the surgical management of sub-axial cervical burst fractures regarding the approach and types of fixation of these injuries. Our Acute Spinal Injury (ASCI) unit prefers anterior only cervical corpectomy and plate fixation in the management of these injuries. The objective of this study was to radiologically assess the long term outcomes (minimum 2 yrs) of our series. Patients and Methods. Patients were identified using the Acute Spinal Injury Unit (ASCI) database that had had anterior only corpectomy and plate fixation for trauma as a standardised procedure between 2006 and 2009. Initial post-op radiological review included the sagittal alignment, hardware characteristics and surgical technique. Radiological review after a minimum of 24 months involved the union, sagittal alignment, hardware characteristics, graft incorporation and adjacent level degeneration at the site of injury. Results. A total of 51 patients were identified but only 11 were available for review at the minimum 24 months. There were 10 males and 1 female with an average age of 28.1years (18–62). The follow up duration was on average 50.6months (27–71) median 60 months. The levels fused were C3-5 (2), C4-6 (5), C5-7 (3), and C4-7 (1 double level). There was NO metalwork failure, NO screw osteolysis and a varying degree of degenerative changes but a 100% FUSION RATE. The average loss of cervical lordosis was 2.5 ° over the follow up period. Conclusion. Anterior stand alone cervical corpectomy and plating alone appears to be a safe, cost effective and time saving alternative in the management of cervical burst fractures in the sub axial spine with no significant long term complications. NO DISCLOSURES

Purpose of study. The vast majority of C2 ring fractures can be managed non-operatively but occasionally the situation precludes this and surgery is considered. Thus study reviews our indications and surgical options in this scenario. Methods. A retrospective review of patient folders and x-rays was performed of all patients with C2 traumatic spondylolisthesis that were managed surgically between 2003 and 2012. Demographic data, particularly indications for surgery, the options chosen and the clinical and radiological outcomes were analysed. Results. Six patients required surgery for a Traumatic Spondylolisthesis of the Axis during this period. Of these 6 cases, 2 were performed for failure of conservative treatment and the other 4 for associated injuries or condition (pregnancy). A variety of surgical methods were utilised including pars repair, C2-C2 posterior fusion and combined anterior C2/3 plating with posterior C1-3 fixation. Osseous healing was achieved in all patients in less than 6 months. There was one case that presented at 3 months post op with an adjacent level subluxation that required application of cones callipers until bony union. There were no infective complications, and no deterioration of neurological findings. Conclusion. Although the majority of Traumatic Spondylolisthesis of the Axis can be managed non-operatively, there are occasional non-spinal reasons to consider surgical stabilisation. There are many options but we would recommend a C2/3 fusion rather than pars repair due to the C2/3 disc trauma and inevitable ankylosis. This can be effectively performed from a posterior approach. NO DISCLOSURES

Introduction. Pedicle subtraction osteotomy is a powerful technique for correcting sagittal imbalance in ankylosing spondylitis. There has been significant perioperative morbidity associated with this technique in the peer review literature. We present the Royal National Orthopaedic Hospital experience with a single surgeon retrospective study that was conducted to evaluate the outcomes in patients who underwent lumbar pedicle subtraction osteotomy for the correction of thoracolumbar kyphotic deformity in ankylosing spondylitis. Method. Twenty seven patients underwent a lumbar pedicle subtraction osteotomy and adjacent level posterior instrumentation between 1995 and 2010. There were 18 males and 9 females in the study. Events during the peri-operative course and post-operative complications were recorded. The radiological outcome and patient satisfaction were analysed with mean follow-up of one and a half years. Results. The mean operative time was three and half hours and the mean blood loss was 2290mls. Final follow-up radiograph showed an increase in lumbar lordosis angle from 17 degrees to 45 degrees. The sagittal imbalance improved by 85mm with the operation. Complications included loosening in two patients, one transient neurologic deficit and one infective non-union occurred overall. There were no mortalities from the surgery. Two patients developed junctional kyphosis and required a repeat operation. There was an improvement in the Oswestry Disability Score from a mean of 29 to 16 after the surgey. All (100%) of the patients were satisfied with the results of the procedure and would recommend the surgey to others. Conclusion. The study shows that pedicle subtraction extension osteotomy is effective for the correction of kyphotic deformity in ankylosing spondylitis

Purpose of study. This RCT is to determine whether or not there is a clinical benefit from inserting a dynamic stabilising implant such as the Wallis ligament on the functional recovery of patients who have undergone lumbar decompression surgery. This Interspinous implant was developed as an anatomically conserving procedure without recourse to lumbar spinal fusion surgery. The biomechanical studies have shown that unloading the disc and facet joints reduces intradiscal pressures at same and adjacent levels. The aim of this study was to identify a patential Wallis affect. Methods. Ethicallly approved. Patients were randomized into 2 groups, decompression alone or decompression with wallis interspinous ligament stabilisation. Patients were assessed pre operatively and post operatively every 6 months by VAS pain score and Oswestry Disability Index. Summary of findings. A total of 60 patients were recriuted the study from October 2005. Equal number had been randomized into two groups. The mean age of 54 (24–85) and the average follow is 36 months (6–48). The results were significantly better in decompression plus Wallis group compared to decompression alone, showing a minimal clinical difference compared to the control group. Relationship between findings and existing knowledge: Our results deomonstrate that clincial outcomes are significantly better when a Wallis implant was used in lumbar deompression. Patients experienced less back pain. Overall significance of findings: The Wallis implant represents a successful non fusion stabilisation device in the treatment of degenerative lumbar spine disease with canal stenosis. Minimal soft tissue dissection, quick rehabilitation, low morbidity. The Wallis ligament sucessfully treats spinal stenosis by reducing pain score, preserving mobility, and function

Background. There have been limited published reports on the clinical results of cervical artificial disc replacement. Goffin et al reported a 90% rate of good to excellent results at 1 to 2 yrs after Bryan disc replacement. Wigfield et al reported a 46% improvement in pain and 31% improvement in disability 2 yrs after Prestige cervical disc replacement. Objectives. The study was designed to determine whether new functional cervical disc prosthesis can provide improvement in the ability to perform activities of daily living, decrease pain and segmental motion. Methods. All patients who had Prestige cervical disc replacement over last 2yrs 3 months were identified. Oswestry disability index score and SF36 Quality of life instrument were administered to each patient. Site specific pain scores were obtained using visual analogue scale. Clinical and operative details were reviewed and correlated. Results. 35 Patients underwent 48 Prestige cervical disc replacement during study period. There was 48%, 54% and 70% improvement in Oswestry disability index at 6 weeks, 6 months and 19 months follow-ups respectively. There was significant improvements in both neck and arm pain during immediate post op period and during further follow-ups. There was one neck wound haematoma and one left sided Horner's syndrome as complications. Conclusion. Anterior cervical disc replacement is a viable surgical alternative to fusion for cervical disc degenerative disease and herniation with preservation of motion and alignment without compromising clinical outcomes. At least 5yrs follow-up will be needed to assess the long term functionality of the prosthesis and protective influence on the adjacent levels

We describe the clinical results of a technique of direct pars repair stabilised with a construct that consists of a pair of pedicle screws connected with a modular link that passes beneath the spinous process. Tightening the link to the screws compresses the bone grafted pars defect providing rigid intrasegmental fixation. 20 patients aged between 9 and 21 years were included in this prospective study. Each of the patients had high activity levels and suffered from significant back pain without radicular symptoms or signs. Patients had either no or grade I spondylolisthesis. Definitive pseudoarthrosis and fracture were confirmed via computerize tomography (CT). Magnetic resonance imaging was performed in every patient to assess the adjacent disc spaces which demonstrated normal signal intensity. A midline incision was used for surgery. The pars interarticularis defect was exposed and filled with autologous iliac crest bone graft prior to screw insertion. After screw insertion, a link was contoured to fit, and placed just caudal to the spinous process, deep to the interspinous ligament of the affected level, and attached to each pedicle screw. There was early mobilization post-operatively without a brace. The average inpatient stay was 3 days. Post-operative complications included 1 superficial wound haematoma and two superficial wound infections which responded to antibiotic treatment. Follow-up was at 6 weeks, 6 months and at 18 months, and 24 months. Clinical assessments for all patients was via the Oswestry disability index (ODI) and visual analogue scores (VAS). At the latest follow-up, 18 out of the 20 patients showed a significant (p<0.05) improvement in their ODI and VAS scores. The mean post-operative ODI score was 8%. All patients had radiographs and CT scans which showed fusion rates of 80% in those patients followed up for a minimum of 24 months. This new technique for direct pars repair demonstrates high fusion rates in addition provides the possible benefits of maintaining adjacent level motion. Clinically this group had good-to excellent functional outcomes as indicated by visual analogue scales and the Oswestry Disability Index in 18 out of 20 patients studied with a minimum follow-up of 2 years

Purpose. A change in lumbar lordosis can affect the outcome following lumbar fusion, and intraoperative positioning is a prime determinant of the postoperative lordosis. The purpose of this study is to determine the change in lordosis and sacral slope (SS) following axial lumbar interbody fusion (AxiaLIF). Method. We retrospectively reviewed 81 patients who underwent a 360 lumbar interbody fusion at L4-5/L5-S1 (two-level procedure) or solely at L5-S1 (one-level) for degenerative disc disease and spondylolithesis utilizing the AxiaLIF with posterior segmental instrumentation. For the two-level procedures, 25 patients had the AxiaLIF placed first and 27 had pedicle screws placed first. For the one-level procedures, 11 patients had the AxiaLIF placed first and 18 had pedicle screws placed first. Standing lateral preoperative radiographs were compared to standing lateral postoperative films. Lumbar Cobb angles were measured at L1-S1, L4-S1 and individual lumbar levels. SS was measured for sacral version. Results. Of the 81 patients studied, 29 underwent one-level AxiaLIF, and 52 underwent two-level AxiaLIF. For the two-level population, there were statistically significant changes (P less than 0.05) in Cobb angles pre- vs. postoperative at the L4-S1, L2-3, and L4-5 levels, but none other. The percent lordosis from L4-S1 pre- vs. postoperative was also noted to be significant. The pre- vs. postoperative Cobb angle comparisons for the one-level population were not found to be significant. The percentages having a greater than or equal to 10 degree change in total lordosis and lordosis from L4-S1 in both one- and two-level groups were similar at ∼20%. There was no difference in either group in percentage having a greater than or equal to five degree change at individual lumbar segments although there was a trend at both L5-S1 and the SS towards less change with the pedicle screws placed first. Conclusion. A significant portion of both single and multilevel fusions with AxiaLIF had a statistically significant change at the L4-5 and L4-S1 levels. In general, there is a small decrease in lordosis at the bottom two segments and SS with reciprocal changes at the proximal levels. The percentage of total lordosis from the L4-S1 level decreased significantly in the multilevel group. Roussouly lordosis type three (well-balanced) was relatively protected from change in lordosis. Placing pedicle screws prior to placing the AxiaLIF in one- and two- level procedures may lead to an improved sagittal alignment. Further observation of this cohort will determine if the change in alignment will impact outcomes or accelerate adjacent level disease