Aims. To report the development of the technique for minimally invasive lumbar decompression using robotic-assisted navigation. Methods. Robotic planning software was used to map out bone removal for a laminar decompression after registration of CT scan images of one cadaveric specimen. A specialized acorn-shaped bone removal robotic drill was used to complete a robotic lumbar laminectomy. Post-procedure advanced imaging was obtained to compare actual bony decompression to the surgical plan. After confirming accuracy of the technique, a minimally invasive robotic-assisted laminectomy was performed on one 72-year-old female patient with lumbar spinal stenosis. Postoperative advanced imaging was obtained to confirm the decompression. Results. A workflow for robotic-assisted lumbar laminectomy was successfully developed in a human cadaveric specimen, as excellent decompression was confirmed by postoperative CT imaging. Subsequently, the workflow was applied clinically in a patient with severe spinal stenosis. Excellent decompression was achieved intraoperatively and preservation of the dorsal midline structures was confirmed on postoperative MRI. The patient experienced improvement in symptoms postoperatively and was discharged within 24 hours. Conclusion. Minimally invasive robotic-assisted lumbar decompression utilizing a specialized robotic bone removal instrument was shown to be accurate and effective both in vitro and in vivo. The robotic bone removal technique has the potential for less invasive removal of laminar bone for spinal decompression, all the while preserving the spinous process and the posterior ligamentous complex. Spinal robotic surgery has previously been limited to the insertion of screws and, more recently, cages; however, recent innovations have expanded robotic capabilities to decompression of neurological structures. Cite this article: Bone Jt Open 2024;5(9):809–817

Study design. A retrospective study design. Objective. To comprehensively compare the 2-year clinical outcome of lumbar laminectomy alone versus lumbar laminetomy supplemented with dynamic stabilization (Dynesys system) in degenerative lumbar stenosis in elderly patients. Material and Methods. A total of 60 elderly patients with an average age of 65.1 years (range, 50 to 78 yrs) affected by lumbar stenosis that underwent lumbar laminectomy alone (30 cases) or lumbar laminectomy with supplementary Dynesys system (30 cases) at our Department were sorted and matched according to three criteria : similar patient age, similar degenerative lumbar desease, and identical operative methods (i.e. levels of laminectomy). Patients were compared according to Oswestry Disability Index (ODI), Roland Morris, SF-36 and VAS outcomes scores. Results. The two cohorts were well matched at 2-years follow-up. Patients treated with lumbar laminectomy alone presented reduced operative time and intraoperative blood loss and reduced postoperative complications, with better clinical outcome compared with patients that received laminectomy with supplementary Dynesys system, for ODI score (28.9 vs 31), Roland Morris (8.25 vs 9.1) and VAS scores (leg pain 36 vs 44.3; back pain 31 vs 38.7), while SF-36 scores resulted similar in both groups of patients. Conclusions. In degenerative lumbar stenosis, supplementary dynamic stabilization in addition to decompressive laminectomy did not presented significant advantages, with respect to functional outcome, in comparison to lumbar laminectomy alone

Aims. Surgical approaches to cervical ossification of the posterior longitudinal ligament (OPLL) remain controversial. The purpose of the present study was to analyze and compare the long-term neurological recovery following anterior decompression with fusion (ADF) and posterior laminectomy and fusion with bone graft and internal fixation (PLF) based on > ten-year follow-up outcomes in a single centre. Methods. Included in this retrospective cohort study were 48 patients (12 females; mean age 55.79 years (SD 8.94)) who were diagnosed with cervical OPLL, received treatment in our centre, and were followed up for 10.22 to 15.25 years. Of them, 24 patients (six females; mean age 52.88 years (SD 8.79)) received ADF, and the other 24 patients (five females; mean age 56.25 years (SD 9.44)) received PLF. Clinical data including age, sex, and the OPLL canal-occupying ratio were analyzed and compared. The primary outcome was Japanese Orthopaedic Association (JOA) score, and the secondary outcome was visual analogue scale neck pain. Results. Compared with the baseline, neurological function improved significantly after surgery in all patients of both groups (p < 0.001). The JOA recovery rate in the ADF group was significantly higher than that in the PLF group (p < 0.001). There was no significant difference in postoperative cervical pain between the two groups (p = 0.387). The operating time was longer and intraoperative blood loss was greater in the PLF group than the ADF group. More complications were observed in the ADF group than in the PLF group, although the difference was not statistically significant. Conclusion. Long-term neurological function improved significantly after surgery in both groups, with the improvement more pronounced in the ADF group. There was no significant difference in postoperative neck pain between the two groups. The operating time was shorter and intraoperative blood loss was lower in the ADF group; however, the incidence of perioperative complications was higher. Cite this article: Bone Jt Open 2024;5(9):768–775

In currently used expansive laminoplasty (ELAP) for cervical spondylotic myelopathy (CSM), persistent axial pain, restriction of neck motion and loss of cervical l ordosis have been the significance postoperative problems. To prevent them, the author has developed skip laminectomy in which ordinary laminectomy at appropriate levels is combined with partial laminectomy of the cephalad half of laminae with preservation of the muscular attachments at adjacent levels. Since December 98, the author performed this procedure on 55 patients with CSM who required multilevel posterior decompressions. Twenty-one of these cases with follow-up period longer than 8 months, with an average of 12 months, were observed. In skip laminectomy, a consecutive four-level decompression between C3/4 and C6/7 as an example is accomplished by removing alternate laminae (C4 and C6), the cephalad half of the C5 and C7 lamina and the ligamentum flava at those four levels. The laminae to be removed were selected after analysis of the pre- and postoperative radiological findings. Intraoperative blood loss averaged 34 grams. The operation time averaged 128 minutes. The patients were allowed to sit up or walk on the first postoperative day without neck support of any kind. An average recovery rate according to the Japanese Orthopaedic Association score was 63%. None of these patients complained of residual axial pain. The postoperative ranges of neck motion on lateral X rays averaged 87% of the preoperative ranges. The spinal curvature index, according to Ishihara’s method, was reduced in only one of the 21 cases. Postoperative atrophy of the deep extensor muscles measured on T2 weighed axial MRI was minimal. Skip laminectomy is less damaging to the posterior extensor muscles and its use reduces the postoperative problems commonly seen after ELAP

AIM: To compare the outcomes between two different surgical techniques for cervical myelopathy (skip laminectomy vs laminoplasty). METHODS: Cervical skip laminectomy is a new technique described by Japanese surgeons in 2000. The advantage of this procedure over the other conventional techniques is it addresses multilevel problem in a least traumatic way without need for instrumentation. We are comparing the above two techniques with 25 patients in each group operated by 3 surgeons. The first group had conventional laminoplasty and the second group underwent the skip laminectomy. The groups were comparable in age, sex, pathology and clinical presentation. Both these group had clinical outcome measurements using SF 12 questionnaires, pre and postoperative clinical assessment with standard tools performed by independent surgeon and a specialist spinal physiotherapist. We also routinely performed pre and postoperative MRI scans to assess the adequacy of decompression. RESULTS & CONCLUSION: There was no significant difference in the outcome of these patients in terms of the operative technique, hospital stay, clinical and radiological outcome. However skip laminectomy is relatively a easier procedure to perform, while the laminoplasty does need instrumentation

Introduction & Aims: The X-stop interspinous process decompression system is being used as an alternative to laminectomy in the treatment of neurogenic claudication. To date the clinical outcomes are favourable, but the economic value has not been established within the NHS financial model. Objective: To compare the average hospital costs of performing an x-stop procedure (under general or local anaesthetic) to a laminectomy in patients with neurogenic claudication. Design: A retrospective analysis of average length of stay, anaesthetic and operative times, equipment and anaesthetic agent costs. Sources included theatre management systems, the British National Formulary and Leeds Teaching Hospitals Trust in-patient stay data. The study period was from April 2005 to October 2006. The number of patients in the two groups were 318 (laminectomy) and 75 (X-stop). Results: In comparison to laminectomy, patients under-going an X-stop procedure have a reduced average length of in-patient stay (3 versus 5 days), reduced anaesthetic time (25 versus 29 minutes) and operative duration (40 versus 128 minutes). The average cost for each procedure is £3346 for an X-stop under general anaesthetic (profit £119), £2835 for a laminectomy (profit £1177) and £2237 for an X-stop as a day case (profit £1228). Conclusions: Tariff reimbursement is an important consideration to ensure insertion of these devices is profitable for the hospital. Our results show that even with the additional cost of the implant device, an X-stop procedure under general anaesthetic remains profitable in comparison to a laminectomy, whilst a day-case X-stop procedure is more profitable. Additional savings are be made by reduced bed and theatre occupancy. Future studies will differentiate costs of 1- and 2-level X-stop procedures, complication rates and revision surgery

Introduction: Spinous process osteotomy (SPO) and multiple laminotomy can be used for multi-level lumbar decompression. We conducted an experimental study to compare the effects of these two methods on spinal kinetics. Method: Ten fresh calf spines (L2- sacrum) were mounted in dental stone and segmental motion of L3 relative to L5 was assessed using an electromagnetic 3-D motion detection system (FASTRAK, Polhemus, Colchester, VT, USA). Pure moments of 0, 2.5, 5, 7, and 10 Nm were used in flexion/extension, right/left lateral bending, and right/left axial rotation. The moments were generated by applying two equal and opposite forces (weights) to the perimeter of a plastic circular disc, which was fixed to the superior end plate of L3 by three screws. In five spines decompression was performed at L3/4 and 4/5 using standard laminotomy technique. Decompression using SPO was done at L3–5 through a unilateral approach in the rest. Segmental mobility between the two methods was compared using the Mann-Whitney test. Results: Mean range of motion in the specimens before intervention was-lateral bending (32.70 ± 7.6 SD), rotation (13.10 ± 4.8 SD), flexion/extension (19.30 ± 7.1 SD). There was statistically significant difference between mean increase in lateral bending after SPO to that following laminotomy (4.00 ± 1.5 SD vs 0.60 ± 1.6 SD; p=0.008). Mean increase in flexion- extension after SPO was not significantly different from that after laminotomy (4.50 ± 1.1 SD vs 3.90 ± 3.8 SD; p= 0.75). There was no difference in the mean increase in axial rotation after SPO compared to that following laminotomy (7.90 ± 3.6 SD vs 6.80 ± 5.0 SD; p= 0.75). Conclusions: Both laminotomy and SPO produced increased range of motion in a calf spine model. SPO produced significant increase in lateral bending although its clinical significance is unknown. Ethics approval: none. Interest Statement: Local grant (Research Fund, Centre for Spinal Studies, Robert Jones and Agnes Hunt Hospital, UK

Introduction and aims: Surgical decompression for lumbar stenosis entails a risk of iatrogenic instability. Consequently, laminectomy has been largely superseded by the more conservative procedure of fenestration, but the decompression may be compromised. We describe an additional technique of undercutting laminectomy, which conserves stability while maximising decompression, and the results are presented. Method: Forty-nine patients with lumbar spinal stenosis were treated by fenestration, medial facetectomy and removal with curved osteotomes of the ventral aspect of the lamina superior to the involved facets together with the attached ligamentum flavum. The results were assessed at a mean follow-up period of three years and four months using walking distance and a pain analogue scale as outcome measures, and surgical complications were recorded. The radiological results were assessed in 25 patients by measurement on MRI scan of the spinal canal cross-sectional area pre- and post-operatively. Results: Ten patients had undercutting laminectomy at one level, 19 at two levels, 14 at three levels and four at four levels. Medical co-morbidity was present in most patients; 11 were ASA 1, 25 ASA2 and 11 ASA 3. Pre-operatively, all patients reported leg pain or numbness and 20 patients reported back pain. All but one had limited walking distance, the mean being 564 metres (range 5m–8000m). Post-operatively the mean pain score was 3.3 and the mean walking distance 762 metres. Forty-one patients said they felt the operation had been worthwhile and six said they did not. Surgical complications occurred in five patients, consisting of dural tear in four patients (repaired with no sequelae) and a wound haematoma requiring drainage in one patient. The mean spinal canal cross-sectional area at the level of maximal stenosis pre-operatively was 28mm. 2. and postoperatively was 75mm. 2. , giving a mean increase of 133%. No patients had any evidence of iatrogenic instability as judged by the development of degenerative spondylolisthesis or scoliosis. Conclusion: The technique described achieves excellent decompression of the stenotic lumbar canal as measured radiologically, while largely preserving the facet joints. In relation to published reports on fenestration and medial facetectomy alone, the clinical results are at least as good

Purpose: The goal of laminectomy is to relieve spinal stenosis and improve radiculopathy. Back pain related to poor trunk muscular conditioning may negatively affect post-operative outcomes. A better understanding of this relationship is important to improve the selection of appropriate surgical candidates. The purpose of this study was to assess the association between cross-sectional lumbar paraspinal muscle area as measured by CT or MRI and outcomes following laminectomy. Method: Prospective observational study of 23 patients undergoing primary elective lumbar laminectomy without fusion who were assessed with pre-operative CT scans. Clinical outcomes were measured with Numerical Pain Scale (NPS) for back and leg pain and the Oswestry Low Back Disability Index (ODI) at baseline and follow-up at a minimum of one year. Lumbar paraspinal muscle cross-sectional area was measured using digital imaging software and adjusted for percent fat infiltration; CT scans evaluations were blinded to clinical outcomes. Results: There were significant improvements in clinical outcomes following laminectomy. ODI decreased from 53.9±11.8 (mean±standard deviation) at baseline to 27.3±20.6 after a follow-up of 15.2±3.5 months. A strong correlation existed between cross-sectional lumbar paraspinal muscle area after adjusting for infiltrating fat content an improvement in ODI (r=0.51, p< 0.02) or back pain NPS (r=0.55, p< 0.02). These relationships remained statistically significant after adjusting for age and body mass index. No significant associations were identified for improvements in leg pain NPS. Conclusion: This study suggests a possible relationship between cross-sectional lumbar paraspinal muscle area and outcomes following laminectomy. This raises important questions regarding the role of trunk muscular conditioning in the etiology of back pain and success of surgery. Further research is required to refine this measurement as a tool to improve patient selection for surgery

Purpose: To measure outcome in patients undergoing decompression for lumbar canal stenosis (LCS) by lami-nectomy. Methods: 100 patients (57 men, 43 women) under one consultant surgeon presenting with neurogenic claudication and MRI confirmed LCS were studied . 23 patients had pre –existing spondylolisthesis (21 Grade 1, 2 Grade-2) and were managed by laminectomy without fixation. Patients completed a set of outcome measure questionnaires (SF-36, Visual analogue scores for back pain, leg pain, leg sensory symptoms and the Roland-Morris back disability score) pre-operatively, 3 months post surgery and at longer term follow up (median 2 years). Outcome scores were analysed and for SF-36 compared to age matched normative data. Statistical significance was calculated using Wilcoxon’s matched pairs and correlations using Spearman’s rank test. Statistical analysis was performed using the SPSS statistical package. Results: Average age 68 years (inter-quartile range 60 – 77). For the cohort visual analogue scores and Roland scores showed significant improvement (p < 0.01) at both 3 months and at long term follow up compared to pre-operative scores. For the physical functioning domain of SF-36, outcome scores improved significantly (p< 0.01) at short and long term follow up with 80% of patients having better long term scores compared to pre-operative scores. The physical functioning domain of SF-36 was significantly correlated with the changes seen in the visual analogue pain scores and the Roland back pain score (p < 0.01). Outcome for the spondylo-listhesis subgroup was similar to the outcome in patients without pre existing spondylolisthesis. Conclusions: Laminectomy for lumbar canal stenosis is an effective treatment resulting in significant health gains which are maintained in the longer term. Our data validates SF-36 as a measurement of disease severity and outcome in this condition

The purpose of this study was to evaluate whether epidural fibrosis formation around the spinal cord was affected by endogenous oestrogen deficient state after lumbar laminectomy in the rats. Thirty-six 12-month-old adult female Sprague-Dawley rats were used in this study. Bilaterally ooferectomy were done in 18 rats. Rats were divided into two groups: oophrectomised (oestrogen deficient) group and sham operated (oestrogen maintained) group. Three weeks after the ooferectomy each rat underwent complete bilaterally laminectomy at the L2 and L3 vertebral levels (two levels per rat). The rats were randomly divided into three equal groups (12 rats in each group). The rats were sacrificed at four, eight, and twelve weeks postoperatively and the lumbar spine excised en bloc, fixed and decalcified. Section stained with hematoxylin and eosin and Masson’s trichrome were used to evaluate epidural fibrosis, acute inflammatory cells, chronic inflammatory cells and vascular proliferation. Sections were analyzed by investigator blinded to the study and graded on a five-point grading system. Statistic were performed using Mann-Whitney U test when compare two variable and Kruskal-Wallis test when compare more than two variables. Compared with the oopherectomised group, the sham operated group showed decreased rate of epidural fibrosis and higher acute and chronic inflammatory cells response at four and eight weeks but this was no statistically significant (p> 0.05). The results of this study revealed that endogenous oestrogen may decrease epidural fibrosis formation after lumbar laminectomy in the rats

Aim: To compare the outcomes between two different surgical techniques for cervical myelopathy (skip laminectomy vs laminoplasty). Methods: Cervical skip laminectomy is a new technique described by Japanese surgeons in 2000. The advantage of this procedure over the other conventional techniques is it addresses multilevel problem in a least traumatic way without need for instrumentation. We are comparing the above two techniques with 25 patients in each group operated by 3 surgeons. The first group had conventional laminoplasty and the second group underwent the skip laminectomy. The groups were comparable in age, sex, pathology and clinical presentation. Both these group had clinical outcome measurements using SF 12 questionnaires, pre and postoperative clinical assessment with standard tools performed by independent surgeon and a specialist spinal physiotherapist. We also routinely performed pre and postoperative MRI scans to assess the adequacy of decompression. Results and Conclusion: here was no significant difference in the outcome of these patients in terms of the operative technique, hospital stay, clinical and radiological outcome. However skip laminectomy is relatively a easier procedure to perform, while the laminoplasty does need instrumentation

Prolonged length of stay (LOS) is a significant contributor to the variation in surgical health care costs and resource utilization after elective spine surgery. The primary goal of this study was to identify patient, surgical and institutional variables that influence LOS. The secondary objective is to examine variability in institutional practices among participating centers. This is a retrospective study of a prospectively multicentric followed cohort of patients enrolled in the CSORN between January 2015 and October 2020. A logistic regression model and bootstrapping method was used. A survey was sent to participating centers to assessed institutional level interventions in place to decrease LOS. Centers with LOS shorter than the median were compared to centers with LOS longer than the median. A total of 3734 patients were included (979 discectomies, 1102 laminectomies, 1653 fusions). The median LOS for discectomy, laminectomy and fusion were respectively 0.0 day (IQR 1.0), 1.0 day (IQR 2.0) and 4.0 days (IQR 2.0). Laminectomy group had the largest variability (SD=4.4, Range 0-133 days). For discectomy, predictors of LOS longer than 0 days were having less leg pain, higher ODI, symptoms duration over 2 years, open procedure, and AE (p< 0.05). Predictors of longer LOS than median of 1 day for laminectomy were increasing age, living alone, higher ODI, open procedures, longer operative time, and AEs (p< 0.05). For posterior instrumented fusion, predictors of longer LOS than median of 4 days were older age, living alone, more comorbidities, less back pain, higher ODI, using narcotics, longer operative time, open procedures, and AEs (p< 0.05). Ten centers (53%) had either ERAS or a standardized protocol aimed at reducing LOS. In this study stratifying individual patient and institutional level factors across Canada, several independent predictors were identified to enhance the understanding of LOS variability in common elective lumbar spine surgery. The current study provides an updated detailed analysis of the ongoing Canadian efforts in the implementation of multimodal ERAS care pathways. Future studies should explore multivariate analysis in institutional factors and the influence of preoperative patient education on LOS

Aims. The escalating demand for medical resources to address spinal diseases as society ages is an issue that requires careful evaluation. However, few studies have examined trends in spinal surgery, especially unscheduled hospitalizations or surgeries performed after hours, through large databases. Our study aimed to determine national trends in the number of spine surgeries in Japan. We also aimed to identify trends in after-hours surgeries and unscheduled hospitalizations and their impact on complications and costs. Methods. We retrospectively investigated data extracted from the Diagnosis Procedure Combination database, a representative inpatient database in Japan. The data from April 2010 to March 2020 were used for this study. We included all patients who had undergone any combination of laminectomy, laminoplasty, discectomy, and/or spinal arthrodesis. Results. This investigation included 739,474 spinal surgeries and 739,215 hospitalizations in Japan. There was an average annual increase of 4.6% in the number of spinal surgeries. Scheduled hospitalizations increased by 3.7% per year while unscheduled hospitalizations increased by 11.8% per year. In-hours surgeries increased by 4.5% per year while after-hours surgeries increased by 9.9% per year. Complication rates and costs increased for both after-hours surgery and unscheduled hospitalizations, in comparison to their respective counterparts of in-hours surgery and scheduled hospitalizations. Conclusion. This study provides important insights for those interested in improving spine care in an ageing society. The swift surge in after-hours spinal surgeries and unscheduled hospitalizations highlights that the medical needs of an increasing number of patients due to an ageing society are outpacing the capacity of existing medical resources. Cite this article: Bone Jt Open 2024;5(8):662–670

Spinal stenosis is a condition resulting in the compression of the neural elements due to narrowing of the spinal canal. Anatomical factors including enlargement of the facet joints, thickening of the ligaments, and bulging or collapse of the intervertebral discs contribute to the compression. Decompression surgery alleviates spinal stenosis through a laminectomy involving the resection of bone and ligament. Spinal decompression surgery requires appropriate planning and variable strategies depending on the specific situation. Given the potential for neural complications, there exist significant barriers to residents and fellows obtaining adequate experience performing spinal decompression in the operating room. Virtual teaching tools exist for learning instrumentation which can enhance the quality of orthopaedic training, building competency and procedural understanding. However, virtual simulation tools are lacking for decompression surgery. The aim of this work was to develop an open-source 3D virtual simulator as a teaching tool to improve orthopaedic training in spinal decompression. A custom step-wise spinal decompression simulator workflow was built using 3D Slicer, an open-source software development platform for medical image visualization and processing. The procedural steps include multimodal patient-specific loading and fusion of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) data, bone threshold-based segmentation, soft tissue segmentation, surgical planning, and a laminectomy and spinal decompression simulation. Fusion of CT and MRI elements was achieved using Fiducial-Based Registration which aligned the scans based on manually placed points allowing for the identification of the relative position of soft and hard tissues. Soft tissue segmentation of the spinal cord, the cerebrospinal fluid, the cauda equina, and the ligamentum flavum was performed using Simple Region Growing Segmentation (with manual adjustment allowed) involving the selection of structures on T1 and/or T2-weighted scans. A high-fidelity 3D model of the bony and soft tissue anatomy was generated with the resulting surgical exposure defined by labeled vertebrae simulating the central surgical incision. Bone and soft tissue resecting tools were developed by customizing manual 3D segmentation tools. Simulating a laminectomy was enabled through bone and ligamentum flavum resection at the site of compression. Elimination of the stenosis enabled decompression of the neural elements simulated by interpolation of the undeformed anatomy above and below the site of compression using Fill Between Slices to reestablish pre-compression neural tissue anatomy. The completed workflow allows patient specific simulation of decompression procedures by staff surgeons, fellows and residents. Qualitatively, good visualization was achieved of merged soft tissue and bony anatomy. Procedural accuracy, the design of resecting tools, and modeling of the impact of bone and ligament removal was found to adequately encompass important challenges in decompression surgery. This software development project has resulted in a well-characterized freely accessible tool for simulating spinal decompression surgery. Future work will integrate and evaluate the simulator within existing orthopaedic resident competency-based curriculum and fellowship training instruction. Best practices for effectively teaching decompression in tight areas of spinal stenosis using virtual simulation will also be investigated in future work

Introduction: Wide laminectomy has been the accepted treatment of choice for stenosis in the lumbar spine. Recently, bilateral laminotomy has been proposed as an alternative decompressive technique for spinal canal stenosis. There have been no biomechanical studies to determine the in vitro difference in stability between these techniques. Objective: To determine the in vitro difference in stability in a functional spinal unit (FSU) following bilateral laminotomy, and compare it to the instability resulting from laminectomy. Methods: Six fresh human cadaver lumbar spines were injured sequentially at the L4-5 level: bilateral laminotomy and laminectomy. The normal and injured spines were subjected to flexion, extension, lateral bending and torsional moments. The three-dimensional motion behaviour of each spine before and after the two injuries was recorded using a magnetic motion sensor. The data from all five spines was pooled for statistical analysis. Results: With flexion and extension loading, bilateral laminotomy induced significantly less sagittal angulation and translation in the FSU than did laminectomy. Significant increases in coronal translation occurred with laminectomy in spines subjected to lateral bending loads. There were no significant differences between the two techniques in coronal plane angulation with lateral bending loads and torsional loads. Discussion: Adequate exposure of the lateral recesses requires limited medial facetectomy with both laminotomy and laminectomy. With laminotomy, the lamina and posterior ligamentous structures are preserved. This is aimed at decreasing the potential late development of spinal instability associated with laminectomy. The increase in motion seen with laminectomy in sagittal angulation / translation, and coronal translation in this in vitro model, may represent clinical instability, and may be responsible for continued symptomatology in these patients. Preservation of the lamina, spinous processes, and the posterior ligamentous structures significantly enhances the biomechanical stability of the FSU

Instrumented fusion for lumbar degenerative spondylolisthesis (LDS) has been challenged recently with high impact trials demonstrating similar changes in health-related quality of life (HRQOL) and less morbidity/cost with laminectomy alone. Randomized trials often fail, however, to evaluate a heterogeneous population of patients. A standardized clinical assessment and management plan (SCAMP) was created as a decision aid for surgeons based on the radiographic stability and clinical presentation of patients. The purpose of this study was to compare outcomes of those patients who followed the decision aid with respect to fusion/no fusion to those who did not. Patients were prospectively enrolled from eleven different Canadian institutions and followed from 2015–2019. A degenerative spondylolisthesis instability classification system (DSIC) was created using best available evidence stratifying patients into three different subtypes (1. stable degenerative spondylolisthesis, 2. potentially unstable spondylolisthesis and 3. unstable spondylolisthesis). The decision aid recommends laminectomy alone for group 1 patients, posterolateral fusion with pedicle screws in type 2 patients and pedicle screw and interbody fusion for type 3 patients. One year changes in HRQOL, length of hospital stay (LOS), medication use and surgical time were compared between each group and in context of whether the treatment fell within the decision aid recommendation. Statistics were performed with STATA software. There were 394 patients initially enrolled and 334 (84.8%) with full one year data available for comparison. There were 95 type 1 (stable), 224 type 2 (potentially unstable) and 75 type 3 (unstable) patients initially classified. Baseline Ostwestry disability index (ODI), EQ-5D, and SF-12 MCS scores were significantly worse for type 3 patients versus type 1 patients. One hundred and eight patients were treated within the recommendations of the DSIC system (108/334, 32.3%). Surgeons performed interbody fusions in 141 patients (42%) rather than follow DSIC recommending a less invasive approach. There were no significant differences EQ-5D, SF-12 PCS/MCS, PHQ-9 or ODI at one year between patient groups. There was a trend towards shorter operating times for those patients following the DSIC system (195 minutes non-followers versus 180 followers, p=0.078) and reduced hospital stay (4.46 days non-followers versus 3.98 followers, p=0.065). There were no significant clinical differences in outcome at 1 year whether patients underwent decompression alone, decompression/posterolateral fusion or interbody fusion regardless of the stability classification. Surgeons were more likely to perform potentially unnecessary interbody fusions even in those patients with stable or potentially unstable spondylolisthesis. Although not statistically significant, there is some suggestion that following the DSIC system based on best evidence recommendations leads to more judicious/responsible use of hospital resources. Further study is required to determine why surgeons are more likely to choose more invasive, higher rigidity constructs in patients with LDS

Objective: To determine the in vitro difference in stability in a functional spinal unit (FSU) following bilateral laminotomy, and compare it to the instability resulting from laminectomy. Design: The normal and injured spines were subjected to flexion, extension, lateral bending and torsional moments. Subjects: Six fresh human cadaver lumbar spines were injured sequentially at the L4–5 level: bilateral laminotomy and laminectomy. Outcome measures: The three-dimensional motion behaviour of each spine before and after the two injuries was recorded using a magnetic motion sensor. The data from all five spines was pooled for statistical analysis. Results: With flexion and extension loading, bilateral laminotomy induced significantly less sagittal angulation and translation in the FSU than did laminectomy. Significant increase in coronal translation occurred with laminectomy in spines subjected to lateral bending loads. There were no significant differences between the two techniques in coronal plane angulation with lateral bending loads and torsional loads. Conclusion: The increase in motion seen with laminectomy in sagittal angulation/translation, and coronal translation in this in vitro model may represent clinical instability, and may be responsible for continued symptomatology in these patients. Preservation of the lamina, spinous processes, and the posterior ligamentous structures significantly enhances the biomechanical stability of the FSU

Objective: We prospectively compared the techniques of skip laminectomy and laminoplasty for the treatment of cervical spondolytic myelopathy in terms extent of decompression achieved, axial pain, postoperative range of cervical motion, patient and surgical outcomes. Methods and results: We studied fifty consecutive patients operated on for cervical spondolytic myelopathy and spinal cord compression as demonstrated on MRI between the levels C3–4 to C6–7. Each patient had a minimum follow-up of two years (2.2 – 4.3 years). Twenty-five patients underwent skip laminectomy and twenty-five patients underwent laminoplasty. Decompression was assessed by pre- and post-operative MRI. Cervical range of motion was assessed by pre- and postoperative flexion and extension radiographs. Patient outcomes were assessed by evaluation of pre-and postoperative neurology and SF12 scores for mental health, physical health and axial pain. Less blood loss and operative times were found with skip laminectomy. Similar degrees of decompression with both techniques. Significantly improved axial pain scores with skip laminectomy. Significantly improved preservation of range of movement with skip laminectomy. Conclusion: Skip laminectomy is an effective procedure for reducing the incidence of postoperative morbidities, such as persisting axial pain, and restriction of neck motion often seen after laminoplasty, and provides adequate decompression of the spinal cord as demonstrated on MRI for a minimum follow-up of two years

A lumbar laminectomy is a commonly performed surgical procedure for the decompression of neural structures. The aim of this human cadaveric study is to establish the extent of pars interarticularis remaining at each lumbar level when a laminectomy is performed to the medial edge of the pedicle. Seven human cadavers with intact lumbar spines were obtained for this study. The lumbar spine was dissected from the body and segmental disarticulation of each level was performed. The isolated lumbar levels had laminectomies performed exposing the neural canal. The vertical alignment of the laminectomy was orientated in line with the medial aspect of the ipsilateral pedicle. The remaining lateral pars interarticularis was measured with a calliper. The procedure was performed bilaterally at each isolated lumbar segment. Five males and two female cadavers with an age range of sixty-eight years to ninety-five years at the time of death. Fourteen lumbar segments of each respective level were available for study except at L5, where only twelve was possible due the presence of a transitional vertebra in one of the specimens. Taken to the nearest mms, the average width of the remnant pars interarticularis at the L1 level was 4 mm, range 3–6 mm (SD 0.95); L2 6 mm, range 5–7 mm (SD 0.77); L3 8mm, range 4–9mm (SD 1.34); L4 11mm, range 9–14 mm (SD 1.31) and L5 16mm, range 13–17 mm (SD 1.15). One way analysis of variance for each of the groups were performed to establish that the difference recorded was greater than that expected by chance (p< 0.05). The results predictably established the gradual narrowing of the pars interarticularis as the levels ascend cranially from L5. The medial wall of the pedicle could be used as an indirect means to establish a satisfactory remnant of the pars interarticularis following a laminectomy in the lower lumbar spine, at the levels of L3 to L5. However in the upper two levels direct visualisation of the pars is recommended