Aims

To report the development of the technique for minimally invasive lumbar decompression using robotic-assisted navigation.

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

Lumbar Spinal Canal Stenosis is a common condition in the ageing population. In Spinal decompression surgery a balance needs to be struck between the need to decompress the neural elements in the spinal canal and the risk of worsening the segmental instability that often coexists in this condition. Traditionally decompression has been supplemented with rigid stabilization e.g. fusion, which is irreversible. Recently semi-rigid or ‘soft’ stabilization philosophies have evolved. The Wallis Device is a second generation interspinous distraction/stabilization implant designed to achieve ‘soft’ segmental stabilization. In addition to stabilising the decompressed segment, it also provides a ‘block’ to full segmental extension, helping to maintain spinal canal dimensions even in the erect position. We followed up and assessed outcomes in 50 patients (25 spinal decompression + Wallis implant and 25 spinal decompression alone). The two arms of the study were matched for gender, age and level of lumbar decompression. A single surgeon was involved in each case and carried out a standard procedure of fenestration and medial facetectomy. Outcomes were assessed during clinical follow-up as well as by telephone, and included the VAS, the Oswestry Disability Index (ODI) and the EQ5D Health Domain. Early results suggest decreased incidence of recurrent symptoms and global improvement in all parameters measured, in those subjects that underwent Spinal decompression with Wallis stabilisation

Standard approaches to thoracic intradural tumors often involve a large incision and significant tissue destruction. Minimally invasive techniques have been applied successfully for a variety of surgical decompression procedures, but have rarely been used for the removal of intradural thoracolumbar tumors. Here we compare the clinical outcome of mini-open resection of intradural thoracolumbar tumors to a standard open technique. We retrospectively reviewed our series of twelve mini-open thoracolumbar intradural tumor resection cases and compared the outcome to a profile matched cohort of six cases of open intradural tumor resection cases. Operative statistics, functional outcome, and complications were compared. Tumors were extirpated successfully with both approaches. There was no statistical difference in operating times, ASIA score improvement, or back pain VAS score improvement between groups. However, the mini-open group had a statistically significantly lower estimated blood loss (146 cc vs. 392 cc) and a significantly shorter length of hospitalization (3.6 vs 7.8 days). There was one complication of pseudomeningocoele formation in the mini-open cohort and no complications in the open cohort. Mean follow-up length was 13 months in the miniopen group compared to 23 months in the open group. The mini-open approach allows for adequate treatment of intradural thoracolumbar tumors with comparable outcomes to standard, open approaches. The mini-open approach is associated with a lower blood loss and a shorter length of stay compared with standard open surgery

Standard approaches to thoracic intradural tumors often involve a large incision and significant tissue destruction. Minimally invasive techniques have been applied successfully for a variety of surgical decompression procedures, but have rarely been used for the removal of intradural thoracolumbar tumors. Here we compare the clinical outcome of mini-open resection of intradural thoracolumbar tumors to a standard open technique. We retrospectively reviewed our series of twelve mini-open thoracolumbar intradural tumor resection cases and compared the outcome to a profile matched cohort of six cases of open intradural tumor resection cases. Operative statistics, functional outcome, and complications were compared. Tumours were extirpated successfully with both approaches. There was no statistical difference in operating times, ASIA score improvement, or back pain VAS score improvement between groups. However, the mini-open group had a statistically significantly lower estimated blood loss (146 cc vs. 392 cc) and a significantly shorter length of hospitalization (3.6 vs 7.8 days). There was one complication of pseudomeningocoele formation in the mini-open cohort and no complications in the open cohort. Mean follow-up length was 13 months in the miniopen group compared to 23 months in the open group. The mini-open approach allows for adequate treatment of intradural thoracolumbar tumors with comparable outcomes to standard, open approaches. The mini-open approach is associated with a lower blood loss and a shorter length of stay compared with standard open surgery

The incidence of degenerative scoliosis in the lumbar spine is not known. In the ageing population deformity may coexist or cause stenosis. MRI gives limited information on this important parameter in the treatment of stenosis. The aim of this study was to highlight the incidence of coronal abnormalities of the lumbar spine dependent on age in a large population of patients. We reviewed all abdominal radiographs performed in our hospital over ten months. 2276 radiographs were analysed for degenerative lumbar scoliosis and lateral vertebral slips in patients who are over 20 years. Evidence of osteoarthritis of the spine was also documented. Radiographs were included if the inferior border of T12 to the superior border of S1 was visualised and no previous spinal surgery was evident (metal work). 2233 (98%) radiographs were included. 48% of patients were female. The incidence of degenerative lumbar scoliosis, lateral listhesis and osteoarthritis increased with age. Degenerative scoliosis was present in 1.6% of 30–39 year olds increasing every decade to 29.7% of patients 90 years or older. In all age groups curves were more frequent and had greater average Cobb angles in female patients. Degenerative lumbar scoliosis starts to appear in the third decade of life increasing in frequency every decade thereafter, affecting almost a third of patients in the ninth decade. It is more common in female patients and has a greater magnitude. Deformity may be even greater on standing views and is important to recognise in all patients that are undergoing lumbar spinal decompressive surgery. A failure to do so may lead to inferior results or the need for further surgery

The incidence of degenerative scoliosis in the lumbar spine is not known. In the ageing population deformity may coexist or cause stenosis. MRI gives limited information on this important parameter in the treatment of stenosis. The aim of this study was to highlight the incidence of coronal abnormalities of the lumbar spine dependent on age in a large population of patients. We reviewed all abdominal radiographs performed in our hospital over ten months. 2276 radiographs were analysed for degenerative lumbar scoliosis and lateral vertebral slips in patients who are ≥ 20 years old. Evidence of osteoarthritis of the spine was also documented. Radiographs were included if the inferior border of T12 to the superior border of S1 was visualised and no previous spinal surgery was evident (metal work). 2233 (98%) radiographs were analysed. 48% of patients were female. The incidence of degenerative lumbar scoliosis, lateral listhesis and osteoarthritis increased with age. Degenerative scoliosis was present in 1.6% of 30–39 year olds increasing every decade to 29.7% of patients 90 years or older. In all age groups curves were more frequent and had greater average Cobb angles in female patients except in the 30–39 year olds - where males equalled females. Degenerative lumbar scoliosis starts to appear in the third decade of life increasing in frequency every decade thereafter, affecting almost a third of patients in the ninth decade. It is more common in female patients and has a greater magnitude. Deformity may be even greater on standing views and is important to recognise in all patients that are undergoing lumbar spinal decompressive surgery. A failure to do so may lead to inferior results or the need for further surgery

Background: Clonidine is an 2 adrenoreceptor and imidazoline receptor agonist which has analgesic, sedative and MAC sparing effects. It has been used orally, intravenously (including as an additive to morphine in PCA devices) and epidurally in combination with local anaesthetics and alone. We hypothesised that epidural administration of clonidine without local anaesthesia might provide adequate postoperative analgesia following spinal surgery without centroneuraxial block, and that if the drug’s effect site is spinal then this might be achieved with smaller doses and with fewer side effects than if given systemically. Method: This randomised controlled trial evaluated the effect of epidural clonidine versus saline on analgesia requirement and pain scores following spinal decompressive surgery. 66 patients were recruited and received a standardized general anaesthetic. At the end of surgery group C received a bolus of 1.5 mcg/kg of epidural clonidine followed by an infusion of 25 mcg/h for 36 to 48 hours. Patients in group P received a similar bolus and infusion of saline. Verbal pain scores, morphine consumption by patient-controlled device (PCA), sedation score, haemodynamic variables and the incidence of PONV were recorded for up to 48 hours. Results: Pain scores in both groups were low, but significantly lower for the first 6 hours in the clonidine group. Cumulative morphine consumption, used as a proxy for pain perception, was significantly lower in the morphine group throughout the whole period; mean (SEM) at 48 hours 62 (7) mg vs 35 (7) mg. Conclusion: Epidural clonidine has a useful effect in post operative pain relief following spinal surgery with few side effects

Introduction. This study investigates the effect of somatisation on results of lumbar surgery. Methods. Pre- and post-operative data of all primary discectomies and posterior lumbar decompressions were prospectively collected. Pain using the Visual Analogue Score (VAS) and disability using the Oswestry Disability Index (ODI) were measured. Psychological assessment used the Distress Risk Assessment Method (DRAM). Follow-up was at 1 year. Results. There were a total of 320 patients (average age 49.7 years). Pre-operatively there were 61 Somatising and 75 psychologically Normal patients. 47 of the pre-operative Somatisers were available for follow-up. All pre-operative parameters were significantly higher compared with the Normal group (back pain VAS 6.3 and 3.8; leg pain VAS 7 and 4.7; ODI 61 and 34.4 respectively). At 1 year follow-up, 23% of the somatising patients became psychologically Normal; 36% became At Risk; 11% became Distressed Depressed; and 30% remained Distressed Somatisers. The post-operative VAS for back and leg pain of the 11 patients who had become psychologically Normal was 3.4 (pre-op 6.8) and 3.2 (pre-op 6.6) respectively. In the 14 patients who remained Distressed Somatisers the corresponding figures were 5.6 (pre-op 7.8) and 6.7 (pre-op 7.0). The post-operative ODI of the 11 patients who had become psychologically Normal was 26.4 (pre-op 55.5). In the 14 patients who remained Distressed Somatisers the corresponding figures were 56.7 (pre-op 61.7). These differences are statistically significant. Discussion. Patients with features of somatisation are severely functionally impaired pre-operatively. One year following lumbar spine surgery, 60% (28) had improved psychologically, 23% (11) were defined as psychologically normal. This was associated with a significant improvement in function and back and leg pain. The 14 (30%) patients who did not improve psychologically and remained somatisers had a poor functional outcome. Our results demonstrate that psychological distress is not an absolute contraindication to lumbar spinal decompressive surgery

Introduction: The incidence of degenerative scoliosis in the lumbar spine is not known. In the ageing population deformity may coexist or cause stenosis. MRI gives limited information on this important parameter and is often the only investigation used pre-operatively in the treatment of stenosis. The aim of this study was to highlight the incidence of coronal abnormalities of the lumbar spine dependent on age in a large population of patients requiring abdominal and KUB radiographs at our institution. Method: We reviewed all abdominal and KUB radiographs performed in our hospital in the first ten months from the introduction of our digital PACS system. 2276 radiographs were analysed for the incidence of degenerative lumbar scoliosis and lateral vertebral slips in patients who are ≥ 20 years old, in ten-year age ranges. Evidence of osteoarthritis of the spine was also documented. Radiographs were included if the inferior border of T12 to the superior border of S1 was visualised and no previous spinal surgery was evident (metal work/laminectomy). Results: 2233 (98%) radiographs were analysed. 48% of patients were female. The youngest patient was 20 and the oldest 101 years. The incidence of degenerative lumbar scoliosis, lateral listhesis and osteoarthritis increased with age. In all age groups curves were more frequent and had greater average Cobb angles in female patients except in the 30–39 year olds–where the males equalled females in frequency and had the greatest Cobb angles. Conclusions: Degenerative lumbar scoliosis starts to appear in the third decade of life and increases in frequency every decade thereafter, affecting almost a third of patients in the ninth decade. It is more common in female patients and has a greater magnitude. Deformity may be even greater on standing views and is important to recognise in all patients that are undergoing lumbar spinal decompressive surgery. A failure to do so may lead to inferior results or the need for further surgery

Introduction: This study investigates the effect of somatisation on results of lumbar surgery. Methods: Pre- and postoperative data of all primary discectomies and posterior lumbar decompressions was prospectively collected. Pain using the Visual Analogue Score (VAS) and disability using the Oswestry Disability Index (ODI) were measured. Psychological assessment used the Distress Risk Assessment Method (DRAM). Follow-up was at 1 year. Results: There were a total of 320 patients (average age 49.7 years). Preoperatively there were 61 Somatising and 75 psychologically Normal patients. 47 of the pre-operative Somatisers were available for follow-up. All pre-operative parameters were significantly higher compared with the Normal group (back pain VAS 6.3 and 3.8; leg pain VAS 7 and 4.7; ODI 61 and 34.4 respectively). At 1 year follow-up, 23% of the somatising patients became psychologically Normal; 36% became At Risk; 11% became Distressed Depressed; and 30% remained Distressed Somatisers. The postoperative VAS for back and leg pain of the 11 patients who had become psychologically Normal was 3.4 (pre-op 6.8) and 3.2 (pre-op 6.6) respectively. In the 14 patients who remained Distressed Somatisers the corresponding figures were 5.6 (pre-op 7.8) and 6.7 (pre-op 7.0). The postoperative ODI of the 11 patients who had become psychologically Normal was 26.4 (pre-op 55.5). In the 14 patients who remained Distressed Somatisers the corresponding figures were 56.7 (pre-op 61.7). These differences are statistically significant. Discussion: Patients with features of somatisation are severely functionally impaired preoperatively. One year following lumbar spine surgery, 60%(28) had improved psychologically, 23%(11) were defined as psychologically normal. This was associated with a significant improvement in function and back and leg pain. The 14(30%) patients who did not improve psychologically and remained somatisers had a poor functional outcome. Our results demonstrate that psychological distress is not an absolute contraindication to lumbar spinal decompressive surgery

Introduction: This study investigates the effect of soma-tisation on results of lumbar surgery. Methods: Pre- and postoperative data of all primary discectomies and posterior lumbar decompressions was prospectively collected. Pain using the Visual Analogue Score (VAS) and disability using the Oswestry Disability Index (ODI) were measured. Psychological assessment used the Distress Risk Assessment Method (DRAM). Follow-up was at 1 year. Results: There were a total of 320 patients (average age 49.7 years). Preoperatively there were 61 Somatising and 75 psychologically Normal patients. 47 of the pre-operative Somatisers were available for follow-up. All pre-operative parameters were significantly higher compared with the Normal group (back pain VAS 6.3 and 3.8; leg pain VAS 7 and 4.7; ODI 61 and 34.4 respectively). At 1 year follow-up, 23% of the somatising patients became psychologically Normal; 36% became At Risk; 11% became Distressed Depressed; and 30% remained Distressed Somatisers. The postoperative VAS for back and leg pain of the 11 patients who had become psychologically Normal was 3.4 (pre-op 6.8) and 3.2 (pre-op 6.6) respectively. In the 14 patients who remained Distressed Somatisers the corresponding figures were 5.6 (pre-op 7.8) and 6.7 (pre-op 7.0). The postoperative ODI of the 11 patients who had become psychologically Normal was 26.4 (pre-op 55.5). In the 14 patients who remained Distressed Somatisers the corresponding figures were 56.7 (pre-op 61.7). These differences are statistically significant. Discussion: Patients with features of somatisation are severely functionally impaired preoperatively. One year following lumbar spine surgery, 60%(28) had improved psychologically, 23%(11) were defined as psychologically normal. This was associated with a significant improvement in function and back and leg pain. The 14(30%) patients who did not improve psychologically and remained somatisers had a poor functional outcome. Our results demonstrate that psychological distress is not an absolute contraindication to lumbar spinal decompressive surgery

Although many authors have emphasised the importance of lumbar spinal decompression surgery for “leg dominant pain”, there is little objective evidence on the outcomes of surgery for varying degrees of back pain compared to leg pain. Moreover, it is unclear whether patients with radicular or claudication type leg pain, presenting with significant back pain as well, would benefit from surgical decompression. This study evaluated the outcomes of patients with. (i.) leg dominant pain compared to patients with. (ii.) leg pain along with significant back pain. A prospective cohort of consenting adult patients, who have consecutively undergone elective primary posterior lumbar decompression surgery at a single academic institution by sub-specialty spinal surgeons were evaluated with longitudinal follow-up using standardised outcomes instruments. The cohort was analyzed into those with. (i.) leg dominant pain and those with. (ii.) significant back pain relative to their leg pain based on pre-operative VAS scores. Univariate and multivariate analyses were used to adjust for potential confounding effects of demographic, surgical, waiting list and psychosocial factors. Of the eighty-five eligible patients, sixty-nine (81.3%) had at least one year follow-up with a mean follow-up time of seventeen months. Baseline factors were similar between the two groups except for back and leg pain and wait times for consultation after referral. Patients with significant back pain waited significantly longer (p = 0.04) for consultation after referral than those with leg dominant pain. Significantly (p = 0.002) more patients (93%) in the leg dominant pain group reported clinically significant improvement in the Oswestry than the significant back pain group (59%). This effect remained after multivariate adjustments for other baseline factors. This study is one of the first to provide objective evidence to support the notion that the primary indication and best predictor of outcome for lumbar decompression surgery is leg dominant pain. Presence of significant back pain, despite presence of leg pain, is a strong predictor of poorer post-operative results. Further research is required to determine if the current long waiting lists are a causative factor for development of significant back pain in surgical candidates