Introduction

In the previous study regarding the relationship among maximum hip flexion, the pelvis, and the lumbar vertebrae on the sagittal plane, we have found in X-rays that the lumbo lordotic angle (LLA) and the sacral slope angle (SSA) have a large impact on hip flexion angle. We examined hip flexion angles to the various height of the objects (half round plastic tube) placed under the subject's lower back and compared the passive hip flexion angles in the supine position between younger and middle age groups.

7% of adolescent idiopathic scoliosis (AIS) patients also present with a pars defect. To date, there are no available data on the results of fusion ending proximal to a spondylolysis in the setting of AIS. The aim of this study was to analyze the outcomes of posterior spinal fusion (PSF) in this patient cohort, to investigate if maintaining the lytic segment unfused represents a safe option. Retrospective review of all patients who received PSF for AIS, presented with a spondylolysis or spondylolisthesis and had a min. 2-years follow-up. Demographic data, instrumented levels and preoperative radiographic data were collected. Mechanical complications, coronal or sagittal parameters, amount of slippage and pain levels were evaluated. Data from 22 patients were available (age 14.4 ± 2.5 years), 18 Lenke 1–2 and four Lenke 3–6. Five patients (24%) had an isthmic spondylolisthesis, all Meyerding I. The mean preoperative Cobb angle of the instrumented curves was 58 ± 13°. For 18 patients the lowest instrumented vertebra (LIV) was the last touched vertebra (LTV); for two LIV was distal to the LTV; for two, LIV was one level proximal to the LTV. The number of segments between the LIV and the lytic vertebra ranged from 1 to 6. At the last follow-up, no complications were observed. The residual curve below the instrumentation measured 8.5 ± 6.4°, the lordosis below the instrumented levels was 51.4 ± 13°. The magnitude of the isthmic spondylolisthesis remained constant for all included patients. Three patients reported minimal occasional low back pain. The LTV can be safely used as LIV when performing PSF for the management of AIS in patients with L5 spondylolysis

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Dysmorphic pelves are a known risk factor for malpositioned iliosacral screws. Improved understanding of pelvic morphology will minimise the risk of screw misplacement, neurovascular injuries and failed fixation. Existing classifications for sacral anatomy are complex and impractical for clinical use. We propose a CT-based classification using variations in pelvic anatomy to predict the availability of transosseous corridors across the sacrum. The classification aims to refine surgical planning which may reduce the risk of surgical complications. The authors postulated 4 types of pelves. The “superior most point of the sacroiliac joint” (sSIJ) typically corresponds with the mid-lower half of the L5 vertebral body. Hence, “the anterior cortex of L5” (L5. a. ) was divided to reference 3 distinct pelvic groups. A 4. th. group is required to represent pelves with a lumbosacral transitional vertebra. The proposed classification:. A – sSIJ is above the midpoint of L5. a. B – sSIJ is between the midpoint and the lowest point of L5. a. C – sSIJ is below the lowest point of L5. a. D – pelves with a lumbosacral transitional vertebra. Specific measures such as the width of the S1 and S2 axial and coronal corridors and the S1 lateral mass angles were used to differentiate between pelvic types. Three-hundred pelvic CT scans were classified into their respective types. Analysis of the specific measures mentioned above illustrated the significant difference between each pelvic type. Changes in the size of S1 and S2 axial corridors formed a pattern that was unique for each pelvic type. The intra- and inter-observer ratings were 0.97 and 0.95 respectively. Distinct relationships between the sizes of S1 and S2 axial corridors informed our recommendations on trans-sacral or iliosacral fixation, number and orientation of screws for each pelvic type. This classification utilises variations in the posterior pelvic ring to offer a planning guide for the insertion of iliosacral screws

The purpose of this study is to evaluate risk factors for distal construct failure (DCF) in posterior spinal instrumented fusion (PSIF) in adolescent idiopathic scoliosis (AIS). We observed an increased rate of DCF when the pedicle screw in the lowest instrumented vertebra (LIV) was not parallel to the superior endplate of the LIV, however this has not been well studied in the literature. We hypothesise a more inferiorly angled LIV screw predisposes to failure and aim to find the critical angle that predisposes to failure. A retrospective cohort study was performed on all patients who underwent PSIF for AIS at the Starship Hospital spine unit from 2010 to 2020. On a lateral radiograph, the angle between the superior endplate of the LIV was measured against its pedicle screw trajectory. Data on demographics, Cobb angle, Lenke classification, instrumentation density, rod protrusion from the most inferior screw, implants and reasons for revision were collected. Of 256 patients, 10.9% (28) required at least one revision. The rate of DCF was 4.6% of all cases (12 of 260) and 25.7% of revisions were due to DCF. The mean trajectory angle of DCF patients compared to all others was 13.3° (95%CI 9.2° to 17.4°) vs 7.6° (7° to 8.2°), p=0.0002. The critical angle established is 11°, p=0.0076. Lenke 5 and C curves, lower preoperative Cobb angle, titanium only rod constructs and one surgeon had higher failure rates than their counterparts. 9.6% of rods protruding less than 3mm from its distal screw disengaged. We conclude excessive inferior trajectory of the LIV screw increases the rate of DCF and a screw trajectory greater than 11° predisposes to failure. This is one factor that can be controlled by the surgeon intraoperatively and by avoiding malposition of the LIV screw, a quarter of revisions can potentially be eliminated

Quantitative assessment of metastatic involvement of the bony spine is important for assessing disease progression and treatment response. Quantification of metastatic involvement is challenging as tumours may appear as osteolytic (bone resorbing), osteoblastic (bone forming) or mixed. This investigation aimed to develop an automated method to accurately segment osteoblastic lesions in a animal model of metastatically involved vertebrae, imaged with micro computed tomography (μCT). Radiomics seeks to apply standardized features extracted from medical images for the purpose of decision-support as well as diagnosis and treatment planning. Here we investigate the application of radiomic-based features for the delineation of osteoblastic vertebral metastases. Osteoblastic lesions affect bone deposition and bone quality, resulting in a change in the texture of bony material physically seen through μCT imaging. We hypothesize that radiomics based features will be sensitive to changes in osteoblastic lesion bone texture and that these changes will be useful for automating segmentation. Osteoblastic metastases were generated via intracardiac injection of human ZR-75-1 breast cancer cells into a preclinical athymic rat model (n=3). Four months post inoculation, ex-vivo μCT images (µCT100, Scanco) were acquired of each rodent spine focused on the metastatically involved third lumbar vertebra (L3) at 7µm/voxel and resampled to 34µm/voxel. The trabecular bone within each vertebra was isolated using an atlas and level-set based segmentation approach previously developed by our group. Pyradiomics, an open source Radiomics library written in python, was used to calculate 3D image features at each voxel location within the vertebral bone. Thresholding of each radiomic feature map was used to isolate the osteoblastic lesions. The utility of radiomic feature-based segmentation of osteoblastic bone tissue was evaluated on randomly selected 2D sagittal and axial slices of the μCT volume. Feature segmentations were compared to ground truth osteoblastic lesion segmentations by calculating the Dice Similarity Coefficient (DSC). Manually defined ground truth osteoblastic tumor segmentations on the μCT slices were informed by histological confirmation of the lesions. The radiomic based features that best segmented osteoblastic tissue while optimizing computational time were derived from the Neighbouring Gray Tone Difference Matrix (NGTDM). Measures of coarseness yielded the best agreement with the manual segmentations (DSC=707%) followed by contrast, strength and complexity (DSC=6513%, 5428%, and 4826%, respectively). This pilot study using a radiomic based approach demonstrates the utility of the NGTDM features for segmentation of vertebral osteoblastic lesions. This investigation looked at the utility of isolated features to segment osteoblastic lesions and found modest performance in isolation. In future work we will explore combining these features using machine learning based classifiers (i.e. decision forests, support vector machines, etc.) to improve segmentation performance

Purpose. Degenerative changes of the lumbar motion segment often lead to stenosis of the spinal canal or neuroforamen. Axial lumbar interbody fusion (AxiaLIF) is intended to indirectly increase and stabilize foraminal dimensions by restoring disc height in patients with degenerative disc disease, thereby relieving axial and radicular pain. Therefore, this study investigated the effects of AxiaLIF on anterior disc height, posterior disc height, foraminal height and foraminal width as well as to determine the effectiveness of this minimally-invasive technique for indirect decompression and restoration of disc height. Method. Eighty-one patients who underwent a 360 degree lumbar interbody fusion at L4-S1 and L5-S1 with AxiaLIF between November 2008 and May 2010 and satisfied all inclusion criteria were included. The preoperative and three-month postoperative digital radiographs were reviewed and analyzed. Disc heights were measured in the planes of the anterior and posterior surfaces of the adjacent vertebral bodies. Foraminal height was measured as the maximum distance between the inferior margin of the pedicle of the superior vertebra and the superior margin of the pedicle of the inferior vertebra. Foraminal width was measured as the shortest distance between the edge of the superior facet of the caudal vertebra and the posterior edge of inferior endplate of the cranial vertebra. Potential magnification error between pre- and post-operative radiographs was corrected using the anterior vertebral height of L5 vertebra. Results. Our study shows that there is a mean increase of 42.0% in posterior disc height (PDH) at L4-5 and 21.5% in anterior disc height (ADH) at L4-5 and PDH mean increase of 33.6% and 16.3% in ADH at L5-S1 in two-level AxiaLIF cases. Similarly the mean change in foraminal height (FH) was 12.6% at L4-5 and 10.8% at L5-S1 in 2-levels AxiaLIF. The mean change in foraminal width (FW) at L4-L5 was 19.9% and 29.1% at L5-S1 in 2-levels AxiaLIF. In the single level AxiaLIF group, the mean change in PDH was 43.1%, the ADH change was 17.5%, the average change in FH was 14.4%, and mean change in FW was 25.3%. The change is reflected as a percentage of the preoperative value. All changes from preoperative to postoperative values were statistically significant. Conclusion. AxiaLIF appears to be an effective minimally invasive device to increase disc height and neuroforaminal area. Our findings appear equivalent to anterior lumbar interbody fusion and transforaminal lumbar interbody fusion in terms of indirect decompression and increase in disc height. This, in combination with the added benefit of preserving the annulus, anterior longitudinal ligament, and posterior longitudinal ligament, suggests the AxiaLIF is an excellent alternative for this patient population. However, additional follow-up studies are necessary to confirm the long-term ability of the implant to maintain fusion and preserve the improvements in disc and foraminal area

The anatomy of the prevertebral region of the neck is of vital importance to orthopaedic surgeons when managing cervical spine trauma. Lateral radiographs are used in the acute assessment of this area as they are readily available and cost effectiveness. Thickening of the retropharyngeal space on a radiograph may be highly suggestive of serious and life-threatening pathologies. Accurate interpretation of radiological evidence is essential to assist the clinician in diagnosis. Current guidelines for radiological measurement state that these prevertebral soft tissues should not exceed 5mm at the midvertebral level of C3 and 20mm at C7. A ratio between soft tissue measurements and the width of the corresponding vertebra has also been championed as this takes into account magnification errors and variation in patient body habitus. Soft tissue measurements greater than 30% of the upper cervical vertebral bodies and greater than 100% of the lower cervical vertebral bodies are considered to be abnormal. The aim of this study was to assess reliability of current radiological guidelines on soft tissue measurement. A review of 200 consecutive normal lateral soft tissue cervical spine radiographs was undertaken. Patients were included if they were immobilised for blunt trauma and were aged 18 or older. Each patient included had cervical pathology excluded by a combination of clinical examination, flexion-extension views, CT and or MRI. Exclusion criteria included those patients with pre-existing cervical or retropharyngeal pathology, those who had been intubated or had a nasogastric tube passed. Two reviewers independently assessed soft tissue and bony widths at C3 and C7 using the PACs Software. All measurements were taken at the mid vertebral level, not at the end plates to ensure any anterior osteophytes did not create a falsely wide measurement. Plane film radiographs of 107 males and 93 females were included with an average age of 53. At the C3 level, mean soft tissue widths were 4.7mm ± 0.84mm SD and ranged from 2.7 to 7.4mm. The mean soft tissue width at C7 was 14.4mm ± 2.8mm SD with a range of 7.1 to 21.0 mm. Our results show 21.5% (43/200) of the patients exceeded the 5mm upper limit and 20% (40/200) exceeded the soft tissue to vertebra ratio at C3. Only 1% (2/200) of patients exceeded the upper limit of 20mm at C7 and only 2% (4/200) exceeded the soft tissue to vertebra ratio. The C3 guideline for maximum soft tissue widths has a poor specificity (78.5%) and the soft tissue to vertebral ratio at this level may also lead to further unnecessary investigation, as it too has a specificity of only 80%. However, the guidelines for PVST measurements at C7 are much more reliable with a specificity of 99.5% for the absolute measurement and 99% for the soft tissue to vertebra ratio. The ratio measurement has not conferred any significant diagnostic benefit over the static measurement. Current guidelines overestimate injuries at the C3 level but seem appropriate at the C7 level. There is no major benefit to using a ratio measurement over an absolute value

Our prospective observational study of patients treated for Thoracolumbar Adolescent Idiopathic Scoliosis (AIS) by anterior instrumentation aimed at investigating the correlation between the radiographic outcome and the recently-developed scoliosis research society self-reported outcomes instrument (SRS-22) which has been validated as a tool for self-assessment in scoliosis patients. Previous patient based questionnaires demonstrated poor correlation with the radiological parameters. Materials and Methods. Pre-operative, post-operative and two years follow-up radiographs of 30 patients were assessed. Thirteen radiographic parameters including Cobb angles and balance were recorded. The percentage improvements for each were noted. The SRS-22 questionnaire was completed by all patients at final follow-up. Correlation was sought between each radiographic parameter, total SRS score and each of the five domains by quantifying Pearson's Correlation Coefficient (r). Results. Percentage improvement in primary Cobb angle (r = 0.052), secondary Cobb angle (r = 0.165), apical vertebra translation of the primary curve (r = -0.353), thoracic kyphosis (r = 0.043) and lumbar lordosis (r = 0.147) showed little or no correlation with the SRS-22 total score and its five individual domains. Significant inverse correlation was found between the upper instrumented vertebra angle and at follow-up and SRS-22 (r = -0.516). The same was true for Sagittal plumb line shift at final follow up (r = -0.447). Conclusion. SRS-22 is a validated tool for the self-assessment of health status in spinal deformity patients; however, it does not seem to correlate with most of the radiographic parameters commonly used by clinicians to assess patient outcome with the exception of upper instrumented vertebra angle and sagittal plumb line which do correlate significantly with the SRS-22 outcomes instrument. A comprehensive system of assessing the success of surgery both from the patient and clinicians perspective is required in the spinal deformity patient

Pedicle screws fixation to stabilise lumbar spinal fusion is the gold standard for posterior stabilisation. Pedicle screws are today positioned in free hand or under fluoroscopic guidance with an error from 20% up to 40–50%, which can determine the inefficacy of treatment or severe damages to close neurologic structures. Surgical navigation drastically increases screws placement accuracy. However its clinical application is limited due to cost reasons and troubles related to the presence of a localiser in the OR and the need to perform a registration procedure before surgery. An alternative image guided approach is the use of patient specific templates similar to the ones used for dental implants or knee prosthesis. Until now, the proposed solutions allow to guide the drill, and in some cases, as templates fit completely around vertebra, they require the complete removal of soft tissues on a large portion of the spine, so increasing intervention invasiveness. To reduce the soft tissue demolition, some authors proposed a fitting based on small “V shape” contact points, but these solutions can determine instability of the template and the reacting of wrong stable positions. In our solution, after spine CT acquisition, each vertebra is segmented using a modified version of ITK-SNAP software, on which the surgeon plans screws positioning and finally the template is designed around the chosen trajectories, using a tool which allows to insert cylinders (full or empty) in the segmented images. Each template, printed in ABS, contains two hollow cylinders, to guide the screws, and multiple contact points on the bone surface, for template stabilisation. We made an in-vitro evaluation on synthetic spine models (by Sawbones) to study different template designs. During this first step an ongoing redesign allowed to obtain an optimal template stability and an easy template positioning to minimise the intervention invasiveness. A first contact point, which fits on the sides of the spinous process, is used to simplify template alignment. The other 4 contact points, which consists of cylinders (diameter 5 mm), fit exactly on spine surface in correspondence to the vertebra's lamina and articular processes to stabilise the template in an unique position. Templates can be used to guide not only the drill, but also Kirschner wires, to guide cannulated screws. After the Kirschner wires insertion the template can be dismounted for its removal (the direction of the kirschner wires are not parallel). After the definitive template design an ex-vivo animal test on 2 porcine specimens has been conducted to evaluate template performance in presence of soft-tissue in place. The specimens have been scanned with CT, we realised a total of 14 templates and we performed the insertion of 28 Kirschner wires. We evaluated that after the soft tissue dissection and the bone exposure, the template can be easily positioned in the right unique position, with no additional tissue removal compared to the traditional approach, requiring just removal of the soft tissue under the small contact points using an electric cutter. The surgeon evaluated (and corrected) some wrong stable template positions when not all the contact points were in contact with the bone surface. The post-op evaluation was made with a CT scan that showed 1 cortical pedicle violation (3.5%) (grade II according to the FU classification)

Image guided surgery (IGS), or “Navigation,” is now widely used in many areas of surgery including arthroplasty. However, the options for establishing, in real time, the veracity of the navigation information are limited. Manufacturers recommend registering with a “prominent anatomical feature” to confirm accurate navigation is being presented. In their fine print, they warrant the accuracy proximate to the navigation array attached to the body. In multi-level spine surgery where it is most sorely needed, this limits the warrants to the vertebra of reference array attachment. In arthroplasty surgery, the accuracy of the system can be erroneous through technical errors and a delay may occur prior to verification of such innacuracy. In response to this situation surgeons have taken to using K-wires, FaxMax screws and a variety of other “Fiducial Markers”, but these were not specifically designed for this purpose and in many ways are inadequate for the task of verification of navigation accuracy. We have developed a fiducial marker that is designed to address these unmet needs. The Precision Screw is clearly visible on imaging modalities and the central registration point is identifiable at any angle of viewing, with accuracy of fractions of a millimeter. It does not interfere with surgery, being low profile and securely fixed to bone. Finally, in use, it is secure in capturing the navigation probe so that the surgeon does not need to focus on keeping the probe located while reviewing the navigation data. We believe these features make this a useful and worthwhile addition to IGS

Introduction. Kinematics analyses of the spine have been recognized as an effective method for functional analysis of the spine. CT is suitable for obtaining bony geometry of the vertebrae but radiation is a clinical concern. MRI is noninvasive but it is difficult to detect bone edges especially at endplates and processes where soft tissues attach. Kinematics analyses require tracking of solid bodies; therefore, bony geometry is not always necessary for kinematics analysis of the spine. This study aimed to develop a reliable and robust method for kinematics analysis of the spine using an innovative MRI-based 3D bone-marrow model. Materials and Methods. This IRB-approved study recruited 17 patients undergoing lumbar decompression surgery to treat a single-level symptomatic herniation as part of a clinical trial for a new dynamic stabilization device. T1 & T2 sagittal MRI scans were acquired as part of the pre-operative evaluation in three positions: supine and with the shoulders rotated 45° to the left and right to induce torsion of the lumbar spine. 3D bone-marrow models of L5 and S1 at the neutral and rotated positions were created by selecting a threshold level of the bone-marrow intensity at bone-marrow/bone interface. Validated 3D-3D registration techniques were used to track movements of L5 and S1. Segmental movements at L5/S1 during torsion were calculated. Results. Bone-marrow models were created not only in the vertebral body but also in superior/inferior, transverse and spinous processes, pedicles and laminae. Segmental rotation (mean±SD) at L5/S1 was shown to be symmetric for both left and right motions (p=0.149; Left: 1.04°±0.93° and Right: 1.33°±0.80°). The range of motion recorded was: left [0.05°-3.70°] and right [0.35°-3.25°]. These values were equivalent to previously reported values of axial lumbar rotation measured by 3D CT lumbar models. Conclusions. This study demonstrated feasibility of kinematic analyses using the 3D bone-marrow model created with clinical MRI. The bone-marrow model shows the bone-marrow/bone interface geometry –the internal structure of the vertebra rather than outside geometry usually used for kinematic analyses– that is easily and consistently detected due to its high-contrast interface MRI intensity, which does not require lengthy manual tracing of the bony contour. The bone-marrow model includes key elements of the vertebra including posterior elements and the 3D-3D registration technique used for 3D-CT model can be applied (Fig.1). This type of methodology can be used in the clinic to evaluate with sufficient accuracy subject-specific spinal kinematics without exposure to additional radiation. The MRI-based 3D bone-marrow model may also be useful for kinematic analyses of other major joints such as hip, knee, ankle and shoulder joints

In recent years internal fixation of the spine by using posterior approach with minimally invasive and percutaneous technique were increasingly used in trauma. The percutaneous surgery lose information and navigation is supposed to provide better data because the lost information is found again. We hypothesise that a percutaneous minimal invasive dorsal procedure by using 3D intra-operative imaging for vertebral fractures allows short operating times with correct screw positioning and does not increase radiation exposure. 59 patients were included in this prospective, monocentric and randomised study. 29 patients (108 implants) were operated on by using conventional surgical procedure (CP) and 30 patients (72 implants) were operated on by using a 3D fluoroscopy-based navigation system (3D fluo). In the two groups, a percutaneous approach was performed for transpedicular vertebroplasty or percutaneous pedicle screws insertion. In the two groups surgery was done from T4 level to L5 levels. Patients (54 years old on average) suffered trauma fractures, fragility fractures or degenerative instabilities. Evaluation of screw placement was done by using post-operative CT with two independent radiologists that used Youkilis criteria. Operative and radiation running time were also evaluated. With percutaneous surgery, the 3D fluo technique was less accurate with 13.88% of misplaced pedicle screws (10/72) compared with 11.11% (12/108) observed with CP. The radiation running time for each vertebra level (two screws) reached on average 0.56 mSv with 3D fluo group compared to 1.57 mSv with the CP group. The time required for instrumentation (one vertebra, two screws) with 3D fluo was 19.75 minutes compared with CP group 9.19 minutes. The results were statistically significant in terms of radiation dose and operative running time (p < 0.05), but not in terms of accuracy (p= 0.24). With percutaneous procedures, 3D fluoroscopy-based navigation (3D fluo) system has no superiority in terms of operative running time and to a lesser degree in terms of accuracy, as compared to 2D conventional procedure (CP), but the benefit in terms of radiation dose is important. Other advantages of the 3D fluo system are twofold: up-to-date image data of patient anatomy and immediate availability to assess the anatomical position of the implanted screws

We present a case series of patients who underwent 3 or 4 part proximal humerus fracture fixation using an intra-osseous suture technique. 18 patients are included in the study with follow up data obtained ranging from 1 to 4 years. Oxford Shoulder Scores (OSS) and range of movement measurements were taken for all patients. The mean OSS for the group was 50/60 with a mean forward flexion of 140°, abduction of 132°, external rotation of 48° and internal rotation to the level 10. th. thoracic vertebra. Three patients developed adhesive capsulitis, 2 requiring subsequent arthroscopic release. This data compares favourably to outcomes reported in the literature with hemiarthroplasty or locking plate fixation. An activity based costing analysis estimated that the treatment costs for proximal humerus fractures was approximately £2,055 when performing a soft tissue reconstruction, £3,114 when using a locking plate and £4,679 when performing a hemiarthroplasty. This demonstrates a significant financial saving when using intra-osseous fixation compared to other fixation techniques. We advocate the use of the intra-osseous suture fixation technique for certain 3 and 4 part fractures. It gives good functional outcomes, significant cost savings and potentially makes revision procedures easier when compared to other fixation techniques

The spinal motion segment relies critically on there being a mechanically robust integration between the compliant disc tissues and the rigid vertebral bone. Achieving such integration represents a major structural challenge. This study explores in detail the microstructural mechanisms involved in both the nucleus-endplate and annulus-endplate regions. Vertebra-nucleus-vertebra samples were obtained from mature ovine lumbar motion segments and subjected to a novel ring-severing technique designed to eliminate the strain-limiting influence of any remaining annular elements. These samples were loaded in tension and then chemically fixed in order to preserve the stretched fibre arrangement, and then decalcified. Annulus-vertebra samples were similarly treated but without any loading prior to fixation. Differential interference contrast optical microscopy was then used to image at high resolution cryosectioned slices of the still integrated disc-vertebral endplate regions while maintained in their fully hydrated state. Structural continuity across the nucleus-endplate junction was sufficient for the samples to support, on average, 20 N before tensile failure occurred. Microscopic examination revealed fibres inserting into the endplates and extending continuously from vertebra to vertebra in the central nuclear region. While the fibres in the nucleus possess a significant level of structural integration with the endplates their role is not primarily a tensile one: rather, in combination with their convoluted geometry, they confer on the nucleus a form of ‘tethered’ mobility. This permits a high degree of shape change in the nucleus during normal disc function in which hydrostatic loading plays an essential role. The annular fibre bundles on entering the endplate are shown to subdivide into sub-bundles to form a 3-D multi-leaf morphology with each leaf separated by cartilaginous endplate matrix. This branched morphology increases the interface area between bundle and matrix in proportion to the number of sub-bundles formed. Our study challenges previously published views on nucleus-endplate relationships. We also show that the robust integration of the annular fibres in the endplate is achieved via a branched morphology exploiting a mechanism of shear-stress transfer, with the anchorage strength optimised over a relatively short endplate insertion depth

Purpopse. Few Cervical Total Disc Replacement (TDR) devices are engineered to address both the Center of Balance (COB) and the Center of Rotation (COR) of the cervical motion segments. The COB is the axis in the intervertebral disc through which the axial compressive load is transmitted. TDRs placed posterior of this point tend to fall into kyphosis while devices placed anterior of this point tend to fall into lordosis. Thus from a “balancing” point of view the ideal placement would be at the COB. However, the COR position has been shown to be posterior and inferior to the disc space. It has also been shown that constrained devices tend to lose motion when there is a mismatch between device and anatomic centers. Mobile core devices may be placed at the COB since their unconstrained rotations and translations allow for the device COR to follow the anatomic COR, but they rely heavily on the facet joints and other anatomic features to resist the paradoxiacal motion. The TriLobe cervical TDR (Figure 2) was engineered for both the COB and COR. The purpose of this study was to compare the 3D kinematic and biomechanical performance of the TriLobe to a ball and trough(BT) cervical TDR in an augmented pure moment cadaveric study to find the ideal AP implant placement. Materials and methods. Specimen were CT imaged for three-dimensional reconstruction. Visual, CT, and DEXA screening was utilized to verify that specimens are free from any defects. Specimens were prepared by resecting all nonligamentous soft tissue leaving the facet joint capsules and spinal ligaments intact. C2 and T1 were potted to facilitate mounting in the testing apparatus (7-axis Spine Tester, Univ. of Utah, Salt Lake City, UT). OptoTRAK motion tracking flags were attached to each vertebra including C2/C3 and T1 to track the 3D motion of each vertebra. •. Specimens C2–T1. •. Treatment Level C5–C6. •. Insertion of fixture pins under fluoro. •. Load Control Testing to 2.5Nm in FE, LB, AR at 0.5Hz. •. 15 Pre-cycles in load control in FE / LB / AR (2.5Nm). •. Test implants in load control in FE / LB / AR to 2.5Nm for 4 cycles with data recorded for all cycles. Results. [Results Table - Figure 1]. Discussion. This study showed that the TriLobe had better control of motion compared to the ball and trough both in ROM and varibility for FE, LB, and AR. The TriLobe had better control of limiting kyphosis over the ball and trough by 41% of the flexion motion. The neutral zone slope, an measure for device stability, showed that the TriLobe was 51% more stable than the BT. AP placement of devices showed there was a general trend of decreasing stability from anterior to posterior placement; however, statistical significance was not established

The aim of our study was to assess the outcome of caudal epidural injection for patients with low back pain in relation to fatty infiltration of spinal muscle. This is a prospective study. The spinal muscles were graded on sagittal section T1 MRI at the lower border of lumber 4 vertebra from 3 to 12 depending on the severity of fatty infiltration. The outcome of the intervention was assessed by improvement in pre and post intervention oswestry disability index score as well as visual analog pain score. Patients with significant fatty changes don't respond well to the caudal epidural injection

This study examines the case of a spondylodiscitis in the thoracic spine caused by MRSA which led to two orthopaedic surgeries followed by rehabilitation. A 72.6 year old woman suffered a cutaneous infection with herpes zoster on the right dorsal thorax – 2 weeks later she presented a sepsis by MSSA. 2 month later she lamented sever pain in the thoracic column. She were hospitalized presenting a sepsis by MRSA. One month later it was found an infectious spondylodiscitis from thoracic vertebra T 8 to T 11 with destruction of the intervertebral spaces. To eliminate the infection and stabilize the dorsal column she was undertaken an first orthopaedic surgery by dorsal decompression and dorsal spondylodesis from T 6 – L 2; intraoperative microbiology: MRSA. 3 month later she was undertaken a second surgery by a lateral transthoracic decompression and intervertebral stabilization from T 9 – T 10 with tricortical bone chips and inlay of sponge with Calcibon and Gentamycin. The following rehabilitation took her to a reasonable result. The cost of the first treatment with dorsal stabilization was € 17.694,24, the second surgery was € 13.678,88; the cost of both rehabilitations was € 4.160,00. The finally costs for the whole treatment for the insurance was € 47,442,62. This retrospective case report shows the high costs for a treatment of spondylodiscitis caused by MRSA, not taking in consideration the harm and prolonged pain of the patient

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

Strain is a robust indicator of bone failure initiation. Previous work has demonstrated the measurement of vertebral trabecular bone strain by Digital Volume Correlation (DVC) of µCT scan in both a loaded and an unloaded configuration. This project aims to improve previous strain measurement methods relying on image registration, improving resolution to resolve trabecula level strain and to improve accuracy by applying feature based registration algorithms to µCT images of vertebral trabecular bone to quantify strain. It is hypothesised that extracting reliable corresponding feature points from loaded and unloaded µCT scans can be used to produce higher resolution strain fields compared to DVC techniques. The feature based strain calculation algorithm has two steps: 1) a displacement field is calculated by finding corresponding feature points identified in both the loaded and unloaded µCT scans 2) strain fields are calculated from the displacement fields. Two methods of feature point extraction, Scale Invariant Feature Transform (SIFT) and Skeletonisation, were applied to unloaded (fixed) and loaded (moving) µCT images of a rat tail vertebra. Spatially non-uniform displacement fields were generated by automatically matching corresponding feature points in the unloaded and loaded scans. The Thin Plate Spline method and a Moving Least Squares Meshless Method were both tested for calculating strain from the displacement fields. Verification of the algorithms was performed by testing against known artificial strain/displacement fields. A uniform and a linearly varying 2% compressive strain field were applied separately to an unloaded 2D sagittal µCT slice to simulate the moving image. SIFT was unable to reliably match identified feature points leading to large errors in displacement. Skeletonisation generated a more accurate and precise displacement field. TPS was not tolerant to small displacement field errors, which resulted in inaccurate strain fields. The Meshless Methods proved much more resilient to displacement field errors. The combination of Skeletonisation with the Meshless Method resulted in best performance with an accuracy of −405µstrain and a detection limit of 1210µstrain at a strain resolution of 221.5µm. The DVC algorithm verified using the same validation test yielded a similar detection limit (1190µstrain), but with a lower accuracy for the same test (2370µstrain) for a lower resolution strain field (770µm) (Hardisty, 2009). The Skeletonisation algorithm combined with the Meshless Method calculated strain at a higher resolution, but with a similar detection limit, to that of traditional DVC methods. Future improvements to this method include the implementation of subpixel feature point identification and adapting this method of strain measurement into a 3D domain. Ultimately, a hybrid DVC/feature registration algorithm may further improve the ability to measure trabecular bone strain using µCT based image registration