There is evidence that various anatomical structures have altered morphology with ageing, and anecdotal evidence of changing lumbar spinous process (LSP) morphology with age. This study aims to clarify the influence of age on LSP morphology, and on lumbar spine alignment. 200 CT scans of the abdomen were reformatted with bone windows allowing precise measurement of LSP dimensions and lumbar lordosis. Observers were blinded to patient demographics. Inter-observer reliability was confirmed. The smallest LSP is at L5. The male LSP is on average 2-3mm higher and 1mm wider than the female LSP. LSP height increases significantly with age at every level in the lumbar spine (P<10. -5. at L2). The LSPs increase in height by 2-5mm between 20-85 years of age (P<10. -6. ), which was as much as 31% at L5 (P<10. -8. ). Width increases proportionally more, by 3-4mm or greater than 50% at each lumbar level (P<10. -11. ). Lumbar lordosis decreases in relation to increasing LSP height (P<10. -4. ) but is independent of increasing LSP width (P=0.2). The height and width of the spinous processes increases with age. Increases in spinous process height are related to a loss of lumbar lordosis and may contribute to sagittal plane imbalance

1. Fifteen patients with spina bifida occulta are described in whom the fifth lumbar spinous process was pressing on the fibrous membrane that closes the spina bifida, or on the bony stumps of the defective lamina. 2. That this is a cause of low back pain, with or without pain referred to the lower limbs, is supported by the findings at operation and the results of treatment. 3. Eleven patients were treated by operation; in each the spinous process of the fifth lumbar vertebra pressed against the spina bifida, either directly or through the vestigial remnant of the first sacral spinous process. 4. In eight cases the fibrous membrane was adherent to the dura mater; in one case the nerve roots were adherent. 5. Excision of the fifth lumbar spinous process and the membrane across the breach of the spina bifida was an effective method of treatment

Background: The Lumbar Spinous Processes (LSP) have an important anatomical and biomechanical function. They also influence access to the spinal canal for neural decompressive surgical procedures. There is evidence that various anatomical structures have altered morphology with ageing, and there is anecdotal evidence of changing LSP morphology with age. This study aims to clarify the influence of age on LSP morphology, and on lumbar spine alignment. Method: 200 CT scans of the abdomen were reformatted with bone windows allowing precise measurement of LSP dimensions, and Lumbar Lordosis. Observers were blinded to patient demographics. Inter-observer reliability was confirmed. Results: The smallest LSP is at L5. The male LSP is on average 2–3mm higher and 1mm wider than the female LSP. LSP height increases significantly with age at every level in the lumbar spine (P< 10-5 at L2). The LSPs increase in height by 2–5mm between 20–85 years of age (P< 10-6), which was as much as 31% at L5 (P< 10-8). Width increases proportionally more, by 3–4mm or greater than 50% at each lumbar level (P< 10-11). Lumbar lordosis decreases in relation to increasing LSP height (P< 10-4) but is independent of increasing LSP width (P=0.2). Conclusions: The height and width of the spinous processes increases with age. Increases in spinous process height are related to a loss of lumbar lordosis and may contribute to sagittal plane imbalance. Conflicts of Interest: None. Source of Funding: None

The study aim was to simulate oblique spinous process abutment (SPA) in cadaveric spines and determine how this affects coupled motion in the coronal plane. L4-S1 spinal segments from thirteen cadavers were loaded on a materials testing machine in pure compression at 1kN for 10 minutes. Reflective markers on the vertebral bodies were used to assess coronal motion using a motion analysis system. Oblique SPA was simulated by attaching moulded oblique aluminium strips to the L4 and L5 spinous processes. In each specimen, both a right- and left-sided SPA was simulated, in random order, and compression at 1kN was again applied. All tests were then repeated after endplate fracture. Coronal plane motion at baseline was compared with values following simulated SPA using Mann Whitney U-tests. Pre-fracture, SPA increased coronal motion by 0.28° and 0.34° on right and left sides respectively, compared to baseline, only the former was significant (P=0.03). Post-fracture, SPA decreased coronal motion by 0.36° and 0.46° on right and left sides respectively, only the latter was significant (P=0.03). Simulated oblique SPA in the intact spine initiated an increase in coronal motion during pure axial loading. These findings provide limited evidence that oblique SPA may be causative in DLS

The purpose of this study was to establish the relationship between the anterior and posterior spinal elements and identify which morphological changes in the ageing spine has the greatest influence in determining the loss of lumbar lordosis. Method. 224 patients' (98 male, 126 female) erect plain lumbar radiographs were reviewed. Lateral plane projections were used to measure the lumbar angle (lordosis), spinous process (SP) height, the interspinous gap (ISG) height, the mid-vertebral body (MVB) height and the mid inter-vertebral disc (MIVD) height of vertebral bodies L1 to L5. The relationship between the heights of these structures and their relative influence and effect on the lumbar angle was investigated using a multiple linear regression model. Results. SP, ISG, MVB and MIVD heights all had a statistically significant influence on determining the lumbar angle (p < 10. −3. ). All heights decreased with age except for the SP height (Graph 1). Age was associated with a decreasing lumbar angle (p 0.134) – (Graph 2). Increasing SP height had an inverse relationship on the lumbar angle. The increase in the SP height had the greatest influence on the lumbar angle (Beta coefficient of -0.71), whilst the MVB and MIVD heights had a lesser influence on determining the lumbar angle (Beta coefficients 0.29 and 0.53 respectively). Conclusion. This study demonstrates that the changing morphology of the SP height in the ageing lumbar spine has the greatest influence on determining the lumbar angle of our measured variables. The relative cumulative effect of the increase in the height of the posterior spinal elements has a greater influence on the loss of the lumbar angle than the cumulative loss of height in the anterior spinal elements in the ageing lumbar spine

Auckland City Hospital, Auckland, New Zealand. To show that the spinous processes (SPs) increase in size with age. To investigate the incidence of SP abutment, relationship to disc degeneration and age related kyphosis. Describe patterns of SP neoarticulation in relation to back pain and intersegmental axial rotation and deformity. We reviewed 200 Abdominal CTs, CT myelograms and 100 standing x-rays (age 18-90 years). We measured SP size, interspinous gap, patterns of neoarticulation, disc height, lumbar lordosis and axial rotation. We compared symptomatic and asymptomatic groups. A 30-50% increase in SP size coupled combined with a loss of disc height leads to increasing rates of SP abutment after the age of 35 years. 30% of people over the age of 60 years have SP abutment. There is a 15 degree increase in standing lumbar kyphosis with age. Four patterns of SP neoarticulation are seen. Degenerative changes in the SP articulation increase by more than 80% in a symptomatic cohort. Oblique SP articulation is 2.5 times more likely in symptomatic individuals and associated with a rotational intersegmental deformity. Ageing is accompanied by SP enlargement and abutment, contributing to a loss of lumbar lordosis. Patterns of neoarticulation and degeneration appear associated with back pain and rotational deformity

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

The Lumbar Spinous Processes (LSP) have an important anatomical and biomechanical function protecting the neural structures in the spinal canal, and as an anchor for the inter and supraspinous ligaments, and the inter-segmental paraspinal muscles. They also influence access to the spinal canal for neural decompressive surgical procedures. More recently the LSPs have attracted increased interest as a site for surgical device attachment in an attempt to both decrease the symptoms of spinal stenosis, and as a site for intersegmental stabilization without formal fusion. There is evidence that various anatomical structures have altered morphology with ageing, and there is anecdotal evidence of changing LSP morphology with age. This study aims to clarify the influence of age on LSP morphology, and on lumbar spine alignment.

200 CT scans of the abdomen were reformatted with bone windows in sagittal and coronal planes allowing precise measurement of LSP dimensions, and Lumbar Lordosis. Observers were blinded to patient demographics. Inter-observer reliability was examined. Data was analysed by an independent statistician.

The smallest LSP is at L5. The male LSP is on average 2–3mm higher and 1mm wider than the female LSP. LSP height increases significantly with age at every level in the lumbar spine (p< 10-5 at L2). The LSPs increase in height by 2–5mm between 20–85 years of age (p< 10-6), which was as much as 31% at L5 (p< 10-8). Width increases proportionally more, by 3–4mm or greater than 50% at each lumbar level (p< 10–11). Lumbar lordosis decreases in relation to increasing LSP height (p< 10-4) but is independent of increasing LSP width (p=0.2).

This study demonstrates that the dimensions of the LSP change with age. Increases in LSP height occur with age. More impressive increases in LSP width occur with advancing age. This study suggests that loss of lumbar lordosis is correlated with changing LSP morphology.

The increased width of the LSP with age influences access to the spinal canal, particularly if midline-preserving approaches are attempted in the ageing population. There is increased bone volume for bone grafting procedures with increasing age. The reduced distance between LSPs with age may influence design of implants that stabilize this region of the spine, and occur not only as a result of disc space narrowing, but also as a consequence of increased LSP dimensions.

Purpose

To observe the safety and efficacy of a minimally destructive decompressive technique without fusion in patients with lumbar stenosis secondary to degenerative spondylolisthesis.

Posterior lumbar interbody fusion (PLIF) is indicated for many patients with pain and/or instability of the lumbar spine. We performed 36 PLIF procedures using the patient’s lumbar spinous process and laminae, which were inserted as a bone graft between two vertebral bodies without using a cage. The mean lumbar lordosis and mean disc height to vertebral body ratio were restored and preserved after surgery. There were no serious complications.

These results suggest that this procedure is safe and effective.

Introduction Central placement of a total disc arthroplasty (TDA) in the coronal plane will result in equivalent facet joint loading, less tendency for lateral core migration, optimum kinematics, and better outcomes. This study was performed to determine which of the radiographic markers – the vertebral body, the pedicles, or the spinous process – provides the most accurate guide to the coronal midline, so to optimise coronal TDA. The coronal midline was defined as the perpendicular bisector of a line drawn between the midpoints of the two facet joints. Methods Axial CT images were reconstructed from 35 abdominal CT’s to show the relevant anatomy at L4, L5, and S1. Measurements were taken comparing the consistency of the midpoints of the vertebral body, the pedicles, and the spinous processes, in relation to the coronal midline. Results The mean distance from the coronal midline to the vertebral body midpoint was 0.55mm (SD 0.45), to the interpedicular midpoint was 0.19mm (SD 0.40), and to the spinous process midpoint was and 1.30mm (SD 1.30). 16% of the distances from the coronal midline to the spinous process midpoint were greater than or equal to 3mm, compared with 0% of the distances to the interpedicular midpoint or the vertebral body midpoint. The interpedicular midpoint was significantly closer to the coronal midline than the spinous process midpoint or the vertebral body midpoint at all levels (p< 0.001). Discussion The interpedicular midpoint is the most accurate guide to the coronal midline. We recommend this landmark be used in preference to the spinous processes or the vertebral body midpoint when placing the implant in TDA. The close location of the interpedicular midpoint to the implant, compared with the more posteriorly located spinous process, means the likelihood of parallax error, by rotation of the patient or the C arm, is reduced using the interpedicular midpoint

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

Purpose: Rogers’ wiring is the most generally used method as stabilization of the cervical distractive-flexion injuries. When there is fracture of the spinous process on the cranial side, it may be easily cut out during tightening of a wire or in the course of rehabilitation. Comparing to Rogers’ wiring, sublaminar-wiring methods reported by Watts in 1993 is useful for the cases of fracture of the spinous process. However, the method is not generally used. The purpose of this paper is to examine an usefulness of the sublaminar-wiring method and our modified technique. Materials: Ten patients with cervical distractive-flexion injury were operated on using the modified Watts’ methods. Operative techniques: We modified as follows. Firstly, we changed a wire system to a cable one. Secondly we make sublaminar wiring easier with a looped silk thread. Namely, the thread was passed under the cranial lamina using an aneurysm-needle. The looped portion of the thread was pulled out from the cranial interlaminar space. A looped cable was passed under the lamina using this loop. The loop of the cable was placed around the spinous process. After one side of the cable was caught again on the spinous process , both ends are bounded and tightened . Result: A reduction of the dislocated cervical spine was well maintained at the follow-up in all cases. Conclusion: Sublaminar wiring method for distractiveflexion injuries of the cervical spine is effective and useful. Our modified technique makes sublaminar wiring safer and easier

Objective: Infants introduced to indoor heated swimming pools in the first year of life show an association with progressive adolescent idiopathic scoliosis (AIS). Similarly control children exposed in this way show an association with vertical spinous process asymmetry. A new method of assessment was used on these controls who were standing in an upright position. Overall, our evidence suggests that indoor heated swimming pools contain a risk factor that predisposes some infants to develop spinal asymmetries years later – progressive AIS in a few and off-vertical spinous process asymmetry in the many. What the risk factor may be and its possible portal of entry into the infant’s body are unknown and possibilities are examined. A subsequent new group of control children confirms the association of indoor heated swimming pools and vertical spinal asymmetry. Risk factors: An irritant gas trichloramine (nitrogen trichloride) has been found to contaminate the air of indoor-chlorinated pools which Bernard et al link to asthma and chronic airway inflammation. Besides the lungs the skin in infants may provide another portal of entry of any chemical risk factors for spinal asymmetries. In connection with a chemical risk factor Nachemson anecdotally noted the development of scoliosis in salmon fry at a fish farm who were exposed to water contaminated after the re-painting of a water regulating dam. Environmental epigenomics and disease susceptibility: Barker and his colleagues and others have shown that the origins of important chronic diseases of adult life may lie in foetal responses to the intrauterine environment and in infants to early postnatal life. Currently, there are British and US medical research projects to gather information on how human genes and environment interact over the years to cause disease; the British project is called Biobank. Another aspect concerns disease susceptibility by spotting gene variants in people who already have specific diseases. Do the suspected risk factors of indoor-chlorinated pools for spinal asymmetries need to be included in such studies? Is there potential for prevention?. In our earlier study we found 61% of the controls taken swimming in the first year of life had vertical spinous process asymmetry. In the subsequent smaller study the incidence even higher (83%). Conclusions:. The evidence reported in our earlier paper suggests that infants introduced to indoor heated swimming pools in the first year of life show an association with spinal asymmetries including progressive AIS and in controls vertical spinous process asymmetry. Subject to confirmation of our observations consideration should be given to chemical risk factors, possible portals of entry, environmental epigenomics and disease susceptibility to altered spinal development. Subsequent controls confirm that the introduction to indoor heated swimming pools in the first year of life is associated with the development of spinal asymmetries

Posterior cervical wiring is commonly performed for patients with spinal instability, but has inherent risks. We report eight patients who had neurological deterioration after sublaminar or spinous process wiring of the cervical spine; four had complete injuries of the spinal cord, one had residual leg spasticity and three recovered after transient injuries. We found no relation between the degree of spinal canal encroachment and the severity of the spinal-cord injury, but in all cases neurological worsening appeared to have been caused by either sublaminar wiring or spinous process wiring which had been placed too far anteriorly. Sublaminar wiring has substantial risks and should be used only at atlantoaxial level, and then only after adequate reduction. Fluoroscopic guidance should be used when placing spinous process wires especially when the posterior spinal anatomy is abnormal

Dimensions of the 60 male human lumbar vertebrae were quantified on their digitalised lateral images, and related to them across the five vertebral levels (range of 20–40 years). Vertebra dimensions’ were defined and referred to the upper endplate. Linear dimensions (mm) were: the length of the whole vertebra and of the spinous process; the anterior/posterior body heights, and the upper/lower endplate lengths. For each of the measurements L3/L1, L3/l2, L3/L4, L3/L5 ratios were calculated. The inclination angle (°) of the lower-end-plate was further calculated. Significant differences were shown by a randomized complete blocks design, post-hoc test (Student-Newman-Keuls), (α< .05). Anterior bodies’ heights ratios progressively decreased from L1 to L5 level, which means a relative increase of the anterior bodies’ heights. Posterior bodies’ heights ratios progressively increased from L1 to L5 level, which means a relative decrease of the posterior bodies’ heights. Lower-endplates inclination angle significantly and progressively increased from L1 to L5 vertebral level. For L1 and L2 (𝛉< 0°), it means that vertebrae are ventrally wedged, whereas L3, L4, L5 vertebrae are dorsally wedged (𝛉< 0°). It could be suggested that individual vertebra morphology contributes to shape the anterior convexity of the lumbar curvature along with the intervertebral discs. Spinous process and vertebral lengths ratios significantly decreased from L1 to L2, and significantly increased from L4 to L5, but no differences between L1vs. L5 neither for L2 vs. L4. It shows that lengths of the spinous process and vertebrae define two segments with same trends at the lumbar spine, the upper L1 and L2 segment; and the lower L4 and L5, which join together at L3 vertebra. This design allows to drawn the concavity of the lower back while standing upright and its convexity while flexing forward

Hip instability is one of the most common causes for total hip arthroplasty (THA) revision surgery. Studies have indicated that lumbar fusion (LF) surgery is a risk factor for hip dislocation. Instrumented spine fusion surgery decreases pelvic tilt, which might lead to an increase in hip motion to accommodate this postural change. To the best of our knowledge, spine-pelvis-hip kinematics during a dynamic activity in patients that previously had both a THA and LF have not been investigated. Furthermore, patients with a combined THA and LF tend to have greater disability. The purpose was to examine spine-pelvis-hip kinematics during a sit to stand task in patients that have had both THA and LF surgeries and compare it to a group of patients that had a THA with no history of spine surgery. The secondary purpose was to compare pain, physical function, and disability between these patients. This cross-sectional study recruited participants that had a combined THA and LF (n=10; 6 females, mean age 73 y) or had a THA only (n=11; 6 females, mean age 72 y). Spine, pelvis, and hip angles were measured using a TrakSTAR motion capture system sampled at 200 Hz. Sensors were mounted over the lateral thighs, base of the sacrum, and the spinous process of the third lumbar,12th thoracic, and ninth thoracic vertebrae. Participants completed 10 trials of a standardized sit-to-stand-to-sit task. Hip, pelvis, lower lumbar, upper lumbar, and lower thoracic sagittal joint angle range of motion (ROM) were calculated over the entire task. In addition, pain, physical function, and disability were measured with clinical outcomes: Hip Disability Osteoarthritis Outcome Score (pain and physical function), Oswestry Low Back Disability Questionnaire (disability), and Harris Hip Score (pain, physical function, motion). Physical function performance was measured using 6-Minute Walk Test, Stair Climb Test, and 30s Chair Test. Angle ROMs during the sit-to-stand-to-sit task and clinical outcomes were compared between THA+LF and THA groups using independent t-tests and effect sizes (d). The difference in hip ROM was approaching statistical significance (p=0.07). Specifically, the THA+LF group had less hip ROM during the sit-to-stand-to-sit task than the THA only group (mean difference=11.17, 95% confidence interval=-1.13 to 23.47), which represented a large effect size (d=0.83). There were no differences in ROM for pelvis (p=0.54, d=0.28) or spinal (p=0.14 to 0.97; d=0.02 to 0.65) angles between groups. The THA+LF group had worse clinical outcomes for all measures of pain, physical function, and disability (p=0.01 to 0.06), representing large effect sizes (d=0.89 to 2.70). Hip ROM was not greater in the THA+LF group, and thus this is unlikely a risk factor for hip dislocation during this specific sit-to-stand-to-sit task. Other functional tasks that demand greater excursions in the joints should be investigated. Furthermore, the lack of differences in spinal and pelvis ROM were likely due to the task and the THA+LF group had spinal fusions at different levels. Combined THA+LF results in worse clinical outcomes and additional rehabilitation is required for these patients

Introduction: Little is known about how the cervical spine resists the high complex loading to which it is often subjected in life. In this study, such loading was applied to cadaveric cervical motion segments in order to a) measure their strength in forward and backwards bending, b) indicate which structures resist bending most strongly, and c) indicate how compressive injury influences the bending properties. Methods: Ten human cervical spines aged 65–88yrs were obtained post-mortem, dissected into 14 motion segments, and stored at −20°C. Subsequently, motion segments were defrosted and secured in dental plaster for testing on a hydraulic materials testing machine. An optical motion capture system recorded specimen movement simultaneously. Specimens were loaded in 2.5sec in combined bending and compression to reach their elastic limit in flexion, and then extension. Experiments were repeated following creep loading, removal of spinous processes, removal of apophyseal joints, and vertebral body compressive damage. Results: On average, full flexion was reached at an angle of 7.2° and a bending moment of 6.8Nm. Full extension occurred at 9.2° and 9.0Nm. Creep loading reduced specimen height by 0.37mm, increased flexion by 1.5° (P< 0.01) but had little effect on extension. After creep, resistance to flexion came from the spinous processes and related ligaments (46%), apophyseal joints (30%), and disc (24%). Resistance to extension came from spinous processes (23%), apophyseal joints (45%), and disc (32%). The compressive strength of discvertebral body specimens was 1.87kN (STD 0.63kN). Compressive damage reduced specimen height by 0.83mm (STD 0.29mm). This reduced the disc’s resistance to flexion by 44% and extension by 18%. Conclusion: Cervical motion segments have approximately 20% of the bending strength, and 45% of the compressive strength, of lumbar specimens of similar age. The relative weakness of the cervical spine in bending may influence the patterns of injury seen in “whiplash”

Introduction: Neck hyperextension (NH) is defined as a progressive increase of lordosis associated with a limitation in flexion of the cervical spine, which ultimately results in an inability to approximate the chin to the sternum. NH may occur in relation to several myopathies. It is characterized by a general weakness and contractures of the axial muscles which produces a progressive increase of lordosis associated with a limitation in flexion of the cervical spine, that forces the patient to assume awkward compensatory postures to maintain balance and level vision. This study reports on operative complications, the degree of correction, the achievement of a solid arthrodesis, the maintenance of the correction and the clinical assessment of 7 patients. Material and methods: Seven patients affected by various myophaties and NH were included. The mean age was 16.5 years (10–28 years). All underwent surgery, in which the paravertebral muscles were detached from the spinous processes and then transversally sectioned in order to bilaterally expose the laminas of vertebrae C2 to C7. The space between C1–C2 appeared mobile, while the spinous processes from C2 to C7 were close together and thus allowed only a very limited motion in between them. Ligamenti interspinosus and nuchae were detached and the facet joints from C2 to C7 were enlarged by capsulotomy. With a spreader rongeur, the interspinous spaces at each level were gently opened. Cortical cancellous autologue graft were shaped into wedges. After careful opening of each interspinous space, the bone wedges were driven between the spinous processes to maintain the achieved correction. The average follow-up time was 10.4 years (2.4–16.5 years). Results: No major surgical complications occurred. At follow-up, the average angle between C2–C7 in neutral position had decreased (p = 0.016) from 50.7 (40–70) to 21.4 (2–50). The range of motion in the C1–C2 joint remained unaffected, while it decreased in C2–C7 (p = 0.016) from 33.5 (15–64) to 1.8 (0–8). In all cases, a solid arthrodesis was achieved. Discussion and conclusion: The follow-up showed significant clinical improvement of posture in all patients. Our study has shown surgical treatment of NH to be an effective method within the whole series of seven patients, achieving both good immediate and good long-term results

Pedicle screws fixation to stabilize lumbar spinal fusion has become the gold standard for posterior stabilization. However their positioning remain difficult due to variation in anatomical shape, dimensions and orientation, which can determine the inefficacy of treatment or severe damages to close neurologic structures. Image guided navigation allows to drastically decrease errors in screw placement but it is used only by few surgeons due to its cost and troubles related to its using, like the need of a localizer in the surgical scenario and the need of a registration procedure. An alternative image guided approach, less expensive and less complex, is the using of patient specific templates similar to the ones used for dental implants or knee prosthesis. Like proposed by other authors we decided to design the templates using CT scans. (slice thickness of 2.0 mm). Template developing is done, for each vertebra, using a modified version of ITK-SNAP 1.5 segmentation software, which allow to insert cylinders (full or empty) in the segmented images. At first we segment the spine bone and then the surgeon chose screw axes using the same software. We design each template with two hollow cylinders aligned with the axes, to guide the insertion in the pedicle, adding contact points that fit on the vertebra, to obtain a template right positioning. Finally we realize the templates in ABS using rapid prototyping. After same in-vitro tests, using a synthetic spine (by Sawbones), we studied a solution to guarantee template stability with simple positioning and minimizing intervention invasiveness. Preliminary ex-vivo animal testing on porcine specimens has been conducted to evaluate template performance in presence of soft-tissue in place, simulating dissection and vertebra exposure. For verification, the surgeon examined post-operative CT-scans to evaluate Kirschner wires positioning. During the ex-vivo animal test sessions, template alignment resulted easy thanks to the spinous process contact point. Their insertion required no additional tissue removal respect to the traditional approach. The positioning of contact points on vertebra's lamina and articular processes required just to shift the soft tissue under the cylinders bases. The surgeon in some cases evaluated false stable template positions since not each of the 4 contact points were actually in contact with the bone surface and tried the right position. CT evaluation demonstrate a positive results in 96.5% of the Kirschner wires implanted. Our approach allows to obtain patient specific templates that does not require the complete removal of soft tissue around vertebra. Guide positioning is facilitated thanks to the using of the spinous processes contact point, while false stable positions can be avoided using four redundant contact points. The templates can be used to guide the drill, the insertion of Kirschner in case of use of cannulated screws or to guide directly the screw. After these preliminary ex-vivo animal tests we obtained the authorization of the Italian Health Ministry to start the human study