Introduction and Objective. Pectus carinatum is a common congenital anterior chest wall deformity, characterized by outward protrusion of sternum and ribcage resulted from rib cartilage overgrowth. The protrusion may be symmetrical or asymmetrical. Pectus carinatum association with mitral valve diseases, Marfan's syndrome, and scoliosis enforces that poor connective tissue development as possible etiological factor. Despite the coexistence of pectus carinatum and scoliosis has attracted the attention of some researchers, the association between pectus carinatum and the other spinal deformities has not been studied comprehensively. The frequency of spinal deformity in patients with pectus carinatum and the mutual relationships of their subtypes are needed to be studied to determine the epidemiological character of the combined deformity and to plan patient evaluation and management. Our study aimed to investigate the association, define the incidence and evaluate the characteristics between different types of spinal deformities and Pectus carinatum. Materials and Methods. Radiological and physical examinations were performed for 117 pectus carinatum patients in Marmara university hospital/Turkey in the years between 2006 and 2013. The incidence of spinal deformity was calculated. Spinal deformities were classified as scoliosis, kyphosis, kyphoscoliosis, and spinal asymmetry, whereas pectus carinatum were subdivided into symmetric and asymmetric subgroups. The relationship between spinal deformities and the symmetrical-asymmetric subtype of pectus excavatum was statistically analyzed, Pearson chi-square test was used to compare the association of qualitative data. The significance level was accepted as p <0.05. Lastly, the angular values of the deformities of scoliosis and kyphosis patients were measured using the Cobb method. In this way, the magnitude of the deformity was given as a numerical value. Results. Spinal deformity was detected in 23 (17 symmetrical PE and 6 asymmetrical PE) of 117 pectus excavatum patients. Scoliosis and kyphosis were seen equally in symmetrical pectus carinatum, whereas scoliosis was seen in 33.3% and kyphosis in 50% in asymmetric pectus carinatum patients, respectively. However, there were no statistically significant differences in the distribution of scoliosis and kyphosis in patients with symmetrical and asymmetrical PE. Idiopathic scoliosis constituted the most common scoliosis group. Congenital kyphosis was not found in any kyphosis patient. The average Cobb angle of scoliosis patients was 32°, and the mean T2-T12 kyphosis angle of these patients was 55.5°, while the average kyphosis angle of those with kyphosis deformity was 71°. Conclusions. Patients with Pectus carinatum have a higher incidence of spinal deformities than the normal population. Such high concomitant incidence should be taken under consideration in evaluating and treating patients presenting with either deformity

The Cochrane Collaboration has produced five new reviews relevant to bone and joint surgery since the publication of the last Cochrane Corner These reviews are relevant to a wide range of musculoskeletal specialists, and include reviews in Morton’s neuroma, scoliosis, vertebral fractures, carpal tunnel syndrome, and lower limb arthroplasty

Anterior vertebral body tethering (AVBT) is a growth modulating procedure used to manage idiopathic scoliosis by applying a flexible tether to the convex surface of the spine in skeletally immature patients. The purpose of this study is to determine the preliminary clinical outcomes for an adolescent patient cohort. 18 patients with scoliosis were selected using a narrow selection criteria to undergo AVBT. Of this cohort, 11 had reached a minimum follow up of 2 years, 4 had reached 18 months, and 3 had reached 6 months. These patients all demonstrated a primary thoracic deformity that was too severe for bracing, were skeletally immature, and were analysed in this preliminary study of coronal plane deformity correction. Using open-source image analysis software (ImageJ, NIH) PA radiographs taken pre-operatively and at regular follow-up visits post-operatively were used to measure the coronal plane deformity of the major and compensatory curves. Pre-operatively, the mean age was 12.0 years (S.D. 10.7 – 13.3), mean Sanders score 2.6 (S.D. 1.8-3.4), all Risser 0 and pre-menarchal, with mean main thoracic Cobb angle of 52° (S.D. 44.2-59.8°). Post-operatively the mean angle decreased to 26.4° (S.D. 18.4-32°) at 1 week, 30.4° (S.D. 21.3-39.6°) at 2 months, 25.7° (S.D. 18.7-32.8°) at 6 months, 27.9° (S.D. 16.2-39.6°) at 12 months, and 36.8° (S.D. 22.6– 51.0°) at 18 months and 38.2° (S.D. 27.6-48.7°) at 2 years. The change in curve at 2 years post-operative was statistically significant (P=0.004). There were 4 tether breakages identified that did not require return to theatre as yet, one patient underwent a posterior spinal instrumented fusion due to curve progression. AVBT is a promising new growth modulation technique for skeletally immature patients with progressive idiopathic scoliosis. This study has demonstrated a reduction in scoliosis severity

Complex spinal deformities can cause pain, neurological symptoms and imbalance (sagittal and/or coronal), severely impairing patients’ quality of life and causing disability. Their treatment has always represented a tough challenge: prior to the introduction of modern internal fixation systems, the only option was an arthrodesis to prevent worsening of the deformity. Then, the introduction of pedicle screws allowed the surgeons to perform powerful corrective manoeuvres, distributing forces over multiple levels, to which eventually associate osteotomies. In treating flexible coronal deformities, in-ternal fixation and corrective manoeuvres may be sufficient: the combination of high density pedicle screws and direct vertebral rotation revolutionized surgical treatment of scoliosis. However, spinal osteotomies are needed for correcting complex rigid deformities; the type of osteot-omy must be chosen according to the aetiology, type and apex of the deformity. When dealing with large radius deformities, spread over multiple levels and without fusion, multiple posterior column os-teotomies such as Smith-Petersen and Ponte (asymmetric, when treating scoliosis) can be performed, dissipating the correction over many levels. Conversely, the management of a sharp, angulated de-formity that involves a few vertebral levels and/or with bony fusion, requires more aggressive 3 col-umn osteotomies such as Pedicle Subtraction Osteotomies (PSO), Bone Disc Bone Osteotomies (BDBO) or Vertebral Column Resection (VCR). Sometimes the deformity is so severe that cannot be corrected with only one osteotomy: in this scenario, multilevel osteotomies can be performed

Background The internet is an increasingly utilised resource for accessing information regarding a variety of heath conditions. YouTube is a popular video sharing platform used to both seek and distribute information online. Materials & Methods. A search for ‘scoliosis’ was carried out using YouTube's search engine and data was collected on the first fifty videos returned. A JAMA score (to determine currency, authorship, source and disclosure) and scoliosis specific score (that measures the amount of information on the diagnosis and treatment options as devised by Mathur et al in 2005; scored 0–32) was recorded for each video to measure quality objectively. Additionally the number of views, number of comments and feedback positivity was documented for each. Data analysis was conducted using R 3.1.4/R Studio 0.98 with control for the age of each video in analysis models. Results. The average number of views per video was 71,152 with an average length of 7 minutes 32 seconds. Thirty six percent of the videos fell under the authorship category of personal experience. The average JAMA score was 1.32/4 and average scoliosis specific score was 5.38/32. There was a positive correlation between JAMA score and number of views P=0.003. However in contrast there was a negative correlation between scoliosis specific score and number of views P=0.01. Conclusions. Online health information has historically been poor and our study shows that in an environment like YouTube which lacks a peer review process, the quality of scoliosis information is low. Further work is needed to determine whether accessing information on YouTube can play a role in patient care other than simple education pertaining to the disease and its management. Level of Evidence. Health Services Study Level 3

Background. Using flexible tethering techniques, porcine models of scoliosis have been previously described. These scoliotic curves showed vertebral wedging but very limited axial rotation. In some of these techniques, a persistent scoliotic deformity was found after tether release. The possibility to create severe progressive true scoliosis in a big animal model would be very useful for research purposes, including corrective therapies. Methods. The experimental ethics committee of the main institution provide the approval to conduct the study. Experimental study using a growing porcine model. Unilateral spinal bent rigid tether anchored to two ipsilateral pedicle screws was used to induce scoliosis on eight pigs. Five spinal segments were left between the instrumented pedicles. The spinal tether was removed after 8 weeks. Ten weeks later the animals were sacrificed. Conventional radiographs and 3D CT-scans of the specimens were taken to evaluate changes in the coronal and sagittal alignment of the thoracic spine. Fine-cut CT-scans were used to evaluate vertebral and disc wedging and axial rotation. Results. After 8 weeks of rigid tethering, the mean Cobb angle of the curves was 24.3 ± 13.8 degrees. Once the interpedicular tether was removed, the scoliotic curves progressed in all animals until sacrifice. During these 10 weeks without spinal tethering the mean Cobb angle reached 50.1 ± 27.1 degrees. The sagittal alignment of the thoracic spine showed loss of physiologic kyphosis. Axial rotation ranges from 10 to 35 degrees. There was no auto-correction of the curve in any animal. A further pathologic analysis of the vertebral segments revealed that animals with greater progression had more damage of the neurocentral cartilages and epiphyseal plates at the sites of pedicle screw insertion. Interestingly, in these animals with more severe curves, compensatory curves were found proximal and distal to the tethered segments. Conclusions. Temporary interpedicular tethering at the thoracic spine induces severe scoliotic curves in pigs, with significant wedging and rotation of the vertebral bodies. As detailed by CT morphometric analysis, release of the spinal tether systematically results in progression of the deformity with development of compensatory curves outside the tethered segment. The clinical relevance of this work is that this tether release model will be very useful to evaluate both fusion and non-fusion corrective technologies in future research. Level of Evidence. Not apply for experimental studies

Background. Finite element (FE) models have become a standard pre-clinical tool to study biomechanics of spine and are used to simulate and evaluate different strategies in scoliosis treatment: examine their efficacy as well as the effect of different implant design parameters. The goal of this study is to investigate, in a system of rods and laminar wires, the effect of the number of wires and their pre-stress on whole spine stiffness. Methods. A generic FE model was developed to represent a full human spine, including vertebrae, intervertebral discs, ligaments, facet and costovertebral joints, and ribcage. Intervertebral discs were modeled with 3D rebar elements with linear elastic material properties. Vertebrae, ribs, sternum, facet joints, cartilage and endplates were modeled with brick elements, and costal muscles with shell elements with linear elastic properties. Furthermore, ligaments were modeled with truss elements with nonlinear hypo-elastic properties. The spine model was instrumented from T7 to T12 with rods and wires modeled as titanium. Nonlinear contact properties were defined for rib neck-vertebra, transverse processes-rib and facet joint sets. The FE model was loaded in flexion and the whole spine instantaneous stiffness was calculated for different wire pre-stressing levels (0.1 to 2 MPa). Similar analyses were performed with changed numbers of wires and whole spine stiffness was calculated. Results. The results show that with increasing the pre-stress level the whole spine instantaneous stiffness increases by up to 6%. Reducing the number of wires decreases the whole spine stiffness almost linearly by 5%. These changes also alter center of rotation of the spine. The results suggest that pre-stressing and number of wires have an effect on whole spine stiffness. Conclusions. In summary, the develop FE model can be used to simulate different treatment strategies and to improve implant designs used in surgical treatment of scoliosis. Level of evidence. FEA study

Introduction Leg length inequalities (LLIs) are a common finding in every orthopaedic practice. They can be classified into anatomical and functional LLIs. LLIs can e.g. cause gait and balance disabilities, low back pain and functional scoliosis of the spine. In patients with a total hip replacement a higher rate of aseptic loosening of the prosthesis was found when LLIs were present (Gurney 2002). Until today LLIs are treated statically by wooden blocs, which are placed under the shorter extremity, until the pelvis is levelled. However, the correction of LLIs should also be evaluated dynamically to examine the influence of correction onto the spine and pelvis during gait. Therefore, we seek to evaluate in this pilot study the influence of simulated LLIs on spine and pelvis during gait. Methods A total of 30 healthy subjects (17 females & 13 males) with an average age of 24.4 years were measured in this study. First, LLIs (1 to 4 cm) were simulated with the subjects standing on a simulation platform, which height could be controlled, as previously described (Betsch 2012). In addition, a specially designed sandal with different insole heights (1 to 4 cm) was used to simulate LLIs under dynamic condition while subjects were walking on a treadmill. Changes in pelvic position and spinal posture caused by the LLIS were measured using a rasterstereographic system (Formetric 4D motion, Diers International GmbH, Germany). All data were checked for Gaussian distribution by the Chi square test. Student t-tests were used to check for differences between the LLIs. The level of significance was set at p

TGF-beta signaling has a well established role not only in adult organ homeostasis but also in skeletal development. Follistatin-like 3 (FSTL3), related to follistatin, is an inhibitor of TGF-beta ligands, with an established role in glucose and fat metabolism. However it has not previously been studied in skeletal development. Using a FSTL3 knock-out (KO) mouse model we have studied both embryonic skeletal development and adult bone phenotypes. Staining for skeletal and cartilage markers during development shows acceleration of skeletal tissue differentiation, with an eventual normalization at E18.5 (which is just prior to birth). Acceleration of bone mineralization occurs during both endochondral and intramembranous ossification. Use of micro-CT imaging highlighted the development of a scoliosis in the KO animals, along with abnormal shape of cranium and cranial sutures. Further investigation of the cranial phenotype in adult KO mice reveals craniosynastosis, with atypical fusion of the frontal suture. These mice have a change in overall cranial shape with shortening of the anterior head and a compensatory expansion of the posterior cranial bones, in a similar fashion to brachyencephaly. Our study therefore highlights a significant role of FSTL3 in skeletal tissue development and mineralization, as well as the development of clinically significant skeletal developmental disorders such as scoliosis, craniosynastosis and brachyencephaly

Summary Statement. Novel radiopaque UHMWPE sublaminar cables may be a promising alternative to gliding pedicle screws or titanium sublaminar cables within a growth-guidance system for the surgical treatment of early onset scoliosis. Introduction. Growth-guidance or self-lengthening rod systems are an alternative to subcutaneous growing rods and the vertical expandable prosthetic titanium rib for the treatment of early onset scoliosis. Their main perceived advantage over growing rods is the marked decrease in subsequent operative procedures. The Shilla growth-guidance system and a modern Luque trolley are examples of such systems; both depend on gliding pedicle screws and/or sliding titanium sublaminar wires. However, the unknown consequences of metal-on-metal wear debris are reason for concern especially in young patients. In this study, instrumentation stability, residual growth in the operated segment after surgery and biocompatibility of the novel radiopaque UHMWPE cables as an alternative to gliding pedicles screws or titanium sublaminar wires were assessed in an immature sheep model. Materials and methods. Twelve immature sheep were treated with segmental sublaminar spinal instrumentation: dual CoCr rods were held in place by pedicle screws at the most caudal instrumented level (L5) and novel radiopaque UHMWPE (Bi. 2. O. 3. additive) woven cables were placed at 5 thoracolumbar levels. Lateral radiographs were taken at 4-week intervals to evaluate growth of the instrumented segment. Four age-matched, unoperated animals served as radiographic control. After 24 weeks follow-up, the animals were sacrificed and the spines were harvested for histological evaluation and CT analysis. Results. No neurological deficits and no complications occurred during the initial postoperative period. One animal died during follow-up due to unknown cause. At sacrifice, none of the cables had loosened and the instrumentation remained stable. Substantial growth occurred in the instrumented segment (L5-T13) in the intervention group. No significant difference in growth of the operated segment was found between the intervention and control groups. Histological analysis showed fibrous encapsulation of the novel radiopaque UHMWPE sublaminar cable in the epidural space, with no evidence of chronic inflammation. Discussion. Novel radiopaque UHMWPE cables may be a promising alternative to gliding pedicle screws or titanium sublaminar cables within a growth-guidance system. UHMWPE cables may improve growth results due to the smooth surface properties of the UHMWPE cable and address concerns regarding the consequences of metal-on-metal wear debris

Background. Proteoglycans (PGs) have long been known to be important to the functioning of the intervertebral disc. The most common PG is aggrecan, but there are also small leucine-rich proteoglycans (SLRPs) which constitute only a small percentage of the total PGs. However, they have many important functions, including organising the collagen, protecting it from degradation and attracting growth factors to the disc. We have examined how the core proteins of these molecules vary in intervertebral discs from patients with different pathologies. Methods. Discs were obtained from patients with scoliosis (n=7, 19–53y), degenerative disc disease (DDD) (n=6, 35–51y) and herniations (n=5, 33–58y). Proteoglycans were extracted and the SLRPs (biglycan, decorin, fibromodulin, keratocan and lumican) were characterised via Western blotting following enzymatic digestion with chondroitinase ABC and keratanase. Results. At least some SLRPs were present in all the discs studied. In addition to the presence of intact SLRP core proteins there was evidence of fragmentation of all the core proteins but especially of biglycan, fibromodulin and keratocan. Biglycan and keratocan were present in the majority of samples with biglycan being highly fragmented in the majority and keratocan usually present as 2 molecular weight bands. Fibromodulin was present in all samples except for 1 scoliotic disc and usually showed a high degree of fragmentation. The intact core protein of lumican was detected in all samples and was only present as a fragment in one of the older scoliosis samples. Decorin was present in a few samples of which half showed fragmentation. Conclusion. Although the number of samples investigated so far is low, fragmentation of these SLRP molecules appears common in the pathological intervertebral disc. These findings are useful not only in helping unravel pathways of disc degeneration, but may also provide early biomarkers of the different pathologies. Conflicts of Interest. None. Source of Funding. None. Acknowledgements: MRC and AR UK for financial support of SR & SO

INTRODUCTION. Growth-guidance constructs are an alternative to growing rods for the surgical treatment of early onset scoliosis (EOS). In growth-guidance systems, free-sliding anchors preserve longitudinal spinal growth, thereby eliminating the need for surgical lengthening procedures. Non-segmental constructs containing ultra-high molecular weight polyethylene (UHMWPE) sublaminar wires have been proposed as an improvement to the traditional Luque trolley. In such a construct, UHMWPE sublaminar wires, secured by means of a knot, serve as sliding anchors at the proximal and distal ends of a construct, while pedicle screws at the apex prevent rod migration and enable curve derotation. Ideally, a construct with the optimal UHMWPE sublaminar wire density, offering the best balance between providing adequate spinal fixation and minimizing surgical exposure, is designed preoperatively for each individual patient. In a previous study, we developed a parametric finite element (FE) model that potentially enables preoperative patient-specific planning of this type of spinal surgery. The objective of this study is to investigate if this model can capture the decrease in range of motion (ROM) after spinal fixation as measured in an experimental study. MATERIALS AND METHODS. In a previous in vitro study, the ROM of an 8-segment porcine spine was measured before and after instrumentation, using different instrumentation constructs with a sequentally decreasing number of wire fixation points. In the current study, the parametric FE model of the thoracolumbar spine was first validated relative to ROM values reported in the literature. The rods, screws, and sublaminar wires were implemented, and the model was subsequently used to replicate the in vitro tests. The experimental and simulated ROM”s for the different instrumentation conditions were compared. RESULTS. Good agreement between in vitro biomechanical tests and FE simulations was observed in terms of the decrease in ROM for the complete construct with wires at each level. The stepwise increase in total ROM with decreasing number of wires at the construct ends was less prominent in silico in comparison to in vitro. CONCLUSION. Important first steps in the implementation and validation of a growth-guidance construct for EOS patients in a patient-specific FE model of the spine have been made in this study. The parametric nature of the FE model allows for rapid personalization. Although further improvements to the model will be necessary to better distinguish between different spinal instrumentation constructs, we conclude that the model can well capture essential aspects of spinal motion and the overall effect of instrumentation

Background. After surgical correction of thoracic scoliosis, an improvement in the cardio-respiratory adaptation to exercise would be expected because of the correction of the rib cage associated with the spinal deformity. This work intended to evaluate the physiologic responses to incremental exercise in patients undergoing surgical correction of adolescent idiopathic scoliosis (AIS). The hypothesis of this study was that the exercise limitations described in patients with AIS could be related with the physical deconditioning instead of being linked to the severity of the vertebral deformity. Methods. Cross-sectional study of the exercise tolerance in a series of patients with AIS type Lenke 1A, before and 2 years after surgical correction. Twenty patients with AIS and 10 healthy adolescents aged between 12 and 17 years old were evaluated. The average magnitude of the curves was 60.3±12.9 Cobb. Cardio-respiratory function was assessed before surgery and at 2-year follow-up by maximal exercise tolerance test on treadmill following a Bruce standard protocol. Maximal oxygen uptake (VO2), VCO2, expiratory volume (VE), and VE/VO2 ratio were registered. Results. Before surgery, AIS patients showed lower values than healthy controls in all cardio-respiratory parameters. The most important restrictions were the VO2max in ml/kg/min. (30.3±5.4 vs 49.9±7.5), VE (43.2±10.3 vs 82.3±10.7) and VE/CO2 ratio (25.0±3.9 vs 29.6±4.2). Contrary to expectations, two years after surgery most of these parameters decreased but differences with preoperative data were no statistically significant. Besides the great correction of the deformity (coronal plane, 71.5%; axial rotation, 49.3%), the cardio-respiratory tolerance to the exercise was not modified by surgery. Conclusions. Patients with moderate-severe AIS showed a limited tolerance to maximal exercise that does not change 2 years after surgery. This findings suggests that the reduced cardio-pulmonary function during exercise is not strictly associated to the spinal deformity, since great corrections of the spinal curves does not improve functional ventilatory parameters. In addition, the results point out a severe exercise deconditioning in AIS patients. Level of evidence. Level IV

Introduction. Discogenic pain is associated with ingrowth of blood vessels and nerves, but uncertainty over the extent of ingrowth is hindering development of appropriate treatments. We hypothesise that adult human annulus fibrosus is such a dense crosslinked tissue that ingrowth via the annulus is confined to a) peripheral regions, and b) fissures extending into the annulus. Methods. Disc tissue was examined from 61 patients (aged 37–75 yrs) undergoing surgery for disc herniation, degeneration or scoliosis. 5 µm sections were stained with H&E to identify structures and tissue types. 30 µm frozen sections were examined using confocal microscopy, following immunostaining for CD31 (an endothelial cell marker), PGP 9.5 and Substance P (general and nociceptive nerve markers, respectively). Fluorescent tags were attached to the antibodies. ‘Volocity’ software was used to calculate numbers and total cross-sectional area of labelled structures, and to measure their distance from the nearest free surface (disc periphery, or annulus fissure). Results. Maximum penetration of blood vessels and nerves from the peripheral annulus was 4,800 µm and 2,200 µm respectively. Maximum distance of nerves and vessels from the nearest free surface was 236 µm and 888 µm. Substance P (but not PGP 9.5) was co-localised with blood vessels, and both number and area of Substance P-stained structures were inversely correlated with grade of disc degeneration. Interpretation. Thick sections and fluorescent markers can show reliably where labelled structures are not present. Results therefore support our hypothesis: deep penetration of nerves into the human annulus occurs only if fissures are present. No conflicts of interest. No funding obtained. This abstract has not been previously published in whole or in part; nor has it been presented previously at a national meeting

Summary Statement. Incorrect pedicle screw placement can lead to neurological complications. Practice outside the operating room on realistic bone models, with force feedback, could improve safety. Pedicle forces in cadaveric specimens are reported, to support development of a training tool for residents. Introduction. Inserting screws into the vertebral pedicles is a challenging step in spinal fusion and scoliosis surgeries. Errors in placement can lead to neurological complications and poor mechanical fixation. The more experienced the surgeon, the better the accuracy of the screw placement. A physical training system would provide orthopaedic residents with the feel of performing pedicle cannulation before operating on a patient. The proposed system consists of realistic bone models mimicking the geometry and material properties of typical patients, coupled with a force feedback probe. The purpose of the present study was to determine the forces encountered during pedicle probing to aid in the development of this training system. Methods. We performed two separate investigations. In the first study, 15 participants (9 expert surgeons, 3 fellows, 3 residents) were asked to press a standard pedicle awl three times onto a mechanical scale, blinded to the force, demonstrating what force they would apply during safe pedicle cannulation and during unsafe cortical breach. In the second study, three experienced surgeons used a standard pedicle awl fitted with a one-degree of freedom load cell to probe selected thoracolumbar vertebrae of eight cadaveric specimens to measure the forces required during pedicle cannulation and deliberate breaching, in randomised order. A total of 42 pedicles were tested. Results. Both studies had wide variations in the results, but were in general agreement. Cannulation (safe) forces averaged approximately 90 N (20 lb) whereas breach (unsafe) forces averaged approximately 135–155 N (30–35 lb). The lowest average forces in the cadaveric study were for pedicle cannulation, averaging 86 N (range, 23–125 N), which was significantly lower (p<0.001) than for anterior breach (135 N; range, 80–195 N); medial breach (149 N; range, 98–186 N) and lateral breach (157 N; range, 114–228 N). There were no significant differences among the breach forces (p>0.1). Cannulation forces were on average 59% of the breach forces (range, 19–84%) or conversely, breach forces were 70% higher than cannulation forces. Discussion. To our knowledge, axial force data have not previously been reported for pedicle cannulation and breaching. A large range of forces was measured, as is experienced clinically. Additional testing is planned with a six-degree-of-freedom load cell to determine all of the forces and moments involved in cannulation and breaching throughout the thoracolumbar spine. These results will inform the development of a realistic bone model as well as a breach prediction algorithm for a physical training system for spine surgery. The opportunity to learn and practice outside of the operating room, including learning from deliberate mistakes, should increase the confidence and comprehension of residents performing the procedure, enhance patient safety, reduce surgical time, and allow faster progression of learning inside the operating room

Introduction. Severe ‘discogenic’ back pain may be related to the ingrowth of nerves and blood vessels, although this is controversial. We hypothesise that ingrowth is greater in painful discs, and is facilitated in the region of annulus fissures. Methods. We compared tissue removed at surgery from 22 patients with discogenic back pain and/or sciatica, and from 16 young patients with scoliosis who served as controls. Wax-embedded specimens were sectioned at 7μm. Nerves and blood vessels were identified using histological stains, and antibodies to PGP 9.5 and CD31 respectively. Results. Blood vessels were identified in 77% of ‘painful’ discs compared to 44% of scoliotic discs (p=0.013), and they were more common in the anterior anulus compared to the posterior (p=0.026). Maximum penetration of blood vessels from the peripheral anulus was 4.7 mm (in ‘painful’ discs) and 2.0 mm (in control discs), and penetration increased with histological grade of disc degeneration in the ‘painful’ discs (p=0.002). In 16/17 ‘painful’ discs, blood vessels were within 1 mm of an anulus fissure, or the disc periphery. Nerves were found in 36% of ‘painful’ discs (all with blood vessels) and 25% of control discs. Nerve ingrowth was always less than or equal to blood vessel ingrowth, with a maximum observed penetration of 1.5 mm from the annulus periphery. Discussion. In degenerated and painful discs, the ingrowth of nerves appears to follow that of blood vessels, and is facilitated in the region of annulus fissures. No nerves were seen >2mm from the annulus periphery, suggesting that previous reports of nerves in the disc nucleus may refer to vertical growth from a vertebral endplate rather than radial growth through the annulus. Results support the view that discogenic back pain is associated with pain-sensitisation events in the disc periphery. Acknowledgements. Research funded by BackCare. M Stefanakis would like to thank the Greek Institute of Scholarships (I.K.Y) for financial support

Growth rods are currently used in young children to hold a scoliosis until the spine has reached a mature length. Only partial deformity correction is achieved upon implantation, and secondary surgeries are required at 6-12 month intervals to lengthen the holding rod as the child grows. This process contains, rather than corrects, the deformity and spinal fusion is required at maturity. This treatment has a significant negative impact on the bio-psychosocial development of the child. Aim. To design a device that would provide a single minimally invasive, non-fusion, surgical solution that permits controlled spinal movement and delivers three dimensional spinal correction. Method. Physical and CAD implant models were developed to predict curve and rotational correction during growth. This allowed use of static structural finite element analysis to identify magnitudes and areas of maximum stress to direct the design of prototype implants. These were mechanically tested for strength, fatigue and wear to meet current Industrial standards. Results. A dynamic hinged construct, was produced. This consisted of carbon nitride coated CoCrMo components assembled in a modular fashion. Five implants were tested under static load to simulate spinal flexion establishing a mean average yield point at a bending moment of 20.8 Nm (SD 2.5 Nm). Six samples were tested for fatigue endurance to 10 million cycles. Two implants were loaded with a 10 Nm maximum bending moment without fracture. Two samples were loaded at 14 Nm with one surviving and one fracturing at 569,048 cycles. Samples loaded at 16 Nm and 17 Nm both fractured at 3,460,359 and 237,613 cycles respectively. Two implants were tested for wear, the first fractured after 290,000 cycles. A second modified implant was tested to ten million cycles and a mean wear rate of 2.03 mg per million cycles was determined during this period. Exposure of the CoCrMo implant substrate was first observed at two million cycles. Conclusion. The device met all mechanical test criteria necessary for CE marking and allowed progression to implant testing in an ovine model

Objectives

To determine the pattern of mutations of the WISP3 gene in clinically identified progressive pseudorheumatoid dysplasia (PPD) in an Indian population.