Vertebral Position Research Articles

Evaluation of Water Retention in Lumbar Intervertebral Disks Before and After Exercise Stress With T2 Mapping.

T2 mapping was used to quantify moisture content of the lumbar spinal disk nucleus pulposus (NP) and annulus fibrosus before and after exercise stress, and after rest, to evaluate the intervertebral disk function. To clarify water retention in intervertebral disks of the lumbar vertebrae by performing magnetic resonance imaging before and after exercise stress and quantitatively measuring changes in moisture content of intervertebral disks with T2 mapping. To date, a few case studies describe functional evaluation of articular cartilage with T2 mapping; however, T2 mapping to the functional evaluation of intervertebral disks has rarely been applied. Using T2 mapping might help detect changes in the moisture content of intervertebral disks, including articular cartilage, before and after exercise stress, thus enabling the evaluation of changes in water retention shock absorber function. Subjects, comprising 40 healthy individuals (males: 26, females: 14), underwent magnetic resonance imaging T2 mapping before and after exercise stress and after rest. Image J image analysis software was then used to set regions of interest in the obtained images of the anterior annulus fibrosus, posterior annulus fibrosus, and NP. T2 values were measured and compared according to upper vertebrae position and degeneration grade. T2 values significantly decreased in the NP after exercise stress and significantly increased after rest. According to upper vertebrae position, in all of the upper vertebrae positions, T2 values for the NP significantly decreased after exercise stress and significantly increased after rest. According to the degeneration grade, in the NP of grade 1 and 2 cases, T2 values significantly decreased after exercise stress and significantly increased after rest. T2 mapping could be used to not only diagnose the degree of degeneration but also evaluate intervertebral disk function. 3.

Experimental validation of a patient-specific model of orthotic action in adolescent idiopathic scoliosis.

Personalized modeling of brace action has potential in improving brace efficacy in adolescent idiopathic scoliosis (AIS). Model validation and simulation uncertainty are rarely addressed, limiting the clinical implementation of personalized models. We hypothesized that a thorough validation of a personalized finite element model (FEM) of brace action would highlight potential means of improving the model. Forty-two AIS patients were included retrospectively and prospectively. Personalized FEMs of pelvis, spine and ribcage were built from stereoradiographies. Brace action was simulated through soft cylindrical pads acting on the ribcage and through displacements applied to key vertebrae. Simulation root mean squared errors (RMSEs) were calculated by comparison with the actual brace action (quantified through clinical indices, vertebral positions and orientations) observed in in-brace stereoradiographies. Simulation RMSEs of Cobb angle and vertebral apical axial rotation was lower than measurement uncertainty in 79% of the patients. Pooling all patients and clinical indices, 87% of the indices had lower RMSEs than the measurement uncertainty. In-depth analysis suggests that personalization of spinal functional units mechanical properties could improve the simulation's accuracy, but the model gave good results, thus justifying further research on its clinical application.

Dimensions of the cervical neural foramen in conditions of spinal deformity: an ex vivo biomechanical investigation using specimen-specific CT imaging.

Patients with cervical spondylosis commonly present with neck pain, radiculopathy or myelopathy. As degenerative changes progress, multiple factors including disc height loss, thoracic kyphosis, and facetogenic changes can increase the risk of neural structure compression. This study investigated the impact of cervical deformity including forward head posture (FHP) and upper thoracic kyphosis, on the anatomy of the cervical neural foramen. Postural changes of 13 human cervical spine specimens (Occiput-T1, age 50.6years; range 21-67) were assessed in response to prescribed cervical sagittal malalignments using a previously reported experimental model. Two characteristics of cervical sagittal deformities, C2-C7 sagittal vertical alignment (SVA) and sagittal angle of the T1 vertebra (T1 tilt), were varied to create various cervical malalignments. The postural changes were documented by measuring vertebral positions and orientations. The vertebral motion data were combined with specimen-specific CT-based anatomical models, which allowed assessments of foraminal areas of subaxial cervical segments as a function of increasing C2-C7 SVA and changing T1 tilt. Increasing C2-C7 SVA from neutral posture resulted in increased neural foraminal area in the lower cervical spine (largest increase at C4-C5: 13.8±15.7%, P<0.01). Increasing SVA from a hyperkyphotic posture (greater T1 tilt) also increased the neural foraminal area in the lower cervical segments (C5-C6 demonstrated the largest increase: 13.4±9.6%, P<0.01). The area of the cervical neural foramen decreased with increasing T1 tilt, with greater reduction occurring in the lower cervical spine, specifically at C5-C6 (-8.6±7.0%, P<0.01) and C6-C7 (-9.6±5.6%, P<0.01). An increase in thoracic kyphosis (T1 tilt) decreased cervical neural foraminal areas. In contrast, an increase in cervical SVA increased the lower cervical neural foraminal areas. Patients with increased upper thoracic kyphosis may respond with increased cervical SVA as a compensatory mechanism to increase their lower cervical neural foraminal area.

The Effect of the Lumbar Vertebral Malpositioning on Bone Mineral Density Measurements of the Lumbar Spine by Dual-Energy X-Ray Absorptiometry

A significant discrepancy between the results of previous human and phantoms studies is identified regarding the effects of vertebral positioning on bone mineral density (BMD) measurements. We aimed to evaluate the effects of lumbar vertebral positioning on BMD measurements by dual-energy X-ray absorptiometry in a human cadaveric spine phantom. A spine phantom was designed using L1–L4 vertebrae harvested from a 48-year-old male cadaver without coronal or sagittal deformity. The spine phantom was scanned by DEXXUM T bone densitometer in a constant scanning speed of 30 mm/s and resolution of 1.0 × 1.0 mm. BMD values were measured in a positive and negative lumbar lordosis and kyphosis tilt angles in the sagittal plane, from 0° to 35°, with 7° increments. Also BMD values were measured in axial and lateral rotations with 5° increments. Projectional dual-energy X-ray absorptiometry measurements are significantly affected by positioning of the lumbar spine, more severely affected by kyphotic curvature, but also by axial and lateral rotational scoliosis as well as lordotic curvature. Increasing the severity of lordosis and kyphosis curvatures leads to false reduction of BMD value up to 17.5% and 11.5%, respectively. Increasing the degree of lateral and axial rotational scolioses results in a false decrease in BMD measurements by up to 10.8% and 9.6%, respectively. To achieve the most accurate scanning results, error sources and abnormal positioning should be identified and minimized as much as possible. If not correctable, they should be taken into consideration while interpreting the results.

WE-AB-BRA-01: 3D-2D Image Registration for Target Localization in Spine Surgery: Comparison of Similarity Metrics Against Robustness to Content Mismatch

Purpose: In image-guided spine surgery, mapping 3D preoperative images to 2D intraoperative images via 3D-2D registration can provide valuable assistance in target localization. However, the presence of surgical instrumentation, hardware implants, and soft-tissue resection/displacement causes mismatches in image content, confounding existing registration methods. Manual/semi-automatic methods to mask such extraneous content is time consuming, user-dependent, error prone, and disruptive to clinical workflow. We developed and evaluated 2 novel similarity metrics within a robust registration framework to overcome such challenges in target localization. Methods: An IRB-approved retrospective study in 19 spine surgery patients included 19 preoperative 3D CT images and 50 intraoperative mobile radiographs in cervical, thoracic, and lumbar spine regions. A neuroradiologist provided truth definition of vertebral positions in CT and radiography. 3D-2D registration was performed using the CMA-ES optimizer with 4 gradient-based image similarity metrics: (1) gradient information (GI); (2) gradient correlation (GC); (3) a novel variant referred to as gradient orientation (GO); and (4) a second variant referred to as truncated gradient correlation (TGC). Registration accuracy was evaluated in terms of the projection distance error (PDE) of the vertebral levels. Results: Conventional similarity metrics were susceptible to gross registration error and failure modes associated with the presence of surgical instrumentation: for GI, the median PDE and interquartile range was 33.0±43.6 mm; similarly for GC, PDE = 23.0±92.6 mm respectively. The robust metrics GO and TGC, on the other hand, demonstrated major improvement in PDE (7.6 ±9.4 mm and 8.1± 18.1 mm, respectively) and elimination of gross failure modes. Conclusion: The proposed GO and TGC similarity measures improve registration accuracy and robustness to gross failure in the presence of strong image content mismatch. Such registration capability could offer valuable assistance in target localization without disruption of clinical workflow. G. Kleinszig and S. Vogt are employees of Siemens Healthcare.

Generation of a Patient-Specific Model of Normal Sagittal Alignment of the Spine

Study DesignMathematical modeling of normal sagittal spinal alignment. ObjectiveTo create a patient specific 3-dimensional (3D) model of normal adolescent spinal shape and alignment. Summary of Background DataRecreating normal sagittal balance is a key goal in spinal deformity surgery. Because of the variation in normal sagittal alignment based on inherent pelvic parameters, it is difficult to know what is normal for a given patient who presents with spinal deformity. MethodsSimultaneous biplanar 2-dimensional digital radiographs were taken for pediatric patients with no known spinal disease using the EOS system. Three-dimensional reconstructions were produced using sterEOS and imported into custom MATLAB software. The researchers defined relationships to approximate orientations and positions of the vertebral bodies from patients' pelvic incidence (PI). The predicted spinal contour was then calculated to optimize congruence to patients' sagittal T1–sacrum offset, sagittal curve inflection point location, and predicted vertebral body orientations and positions. ResultsA total of 75 patients (26 male and 49 female) were included, mean age 14.5 ± 2.6 years. Baseline measurements were PI 46.7° ± 10.2°, sacral lope 40.2° ± 8.9°, T1–T12 kyphosis 39.8° ± 8.8°, and L1–L5 lordosis −37.1° ± 11.2°. Average difference in vertebral position in the anteroposterior direction between actual spines and their predicted models was 1.2 ± 1.2 mm and varied from an absolute minimum of 0.2 mm (T3) to an absolute maximum of 3.7 mm (L2). ConclusionsThis model uses an adolescent patient's PI to predict the normal sagittal alignment that best matches that patient's native sagittal curve. The model was validated on patients with no spinal deformity; average difference between actual sagittal positions of each vertebra and those predicted by the model was less than 5 mm at each vertebral level. This model may be useful in adolescent scoliotic patients with altered sagittal alignment to determine the magnitude of 3D deformity (compared with predicted normal values) and the completeness of 3D correction.

Inter- and Intra-observer Agreement of the Motion Palpation Test for Lumbar Vertebral Rotational Asymmetry.

To investigate inter- and intra-observer agreement in the assessment of lumbar vertebral rotational (VR) asymmetry by a motion palpation test. For this prospective and descriptive test-retest study, 51 asymptomatic participants (40 women, 11 men; mean age 23.3 [SD 5.6] years) were recruited from the community. Each participant was assessed in two sessions by the same three observers, who assessed VR by means of a palpatory test for movement asymmetry. This test is performed by applying posteroanterior pressure in an alternating manner to the left and right transverse processes of a vertebra to determine motion asymmetry in the transverse plane and thus the vertebral position. Observers classified the vertebral position as neutral, rotation to the right, and rotation to the left; they were blinded to which participant was being assessed and to any previous results. Intra- and inter-observer agreement was verified by the kappa coefficient (κ) and the weighted kappa coefficient (κ w ). Values of κ and κ w varied from 0.07 (95% CI, -0.10 to 0.245) to 0.37 (95% CI, 0.11-0.63) for intra-observer agreement and from 0.12 (95% CI, -0.06 to 0.29) to 0.30 (95% CI, 0.08-0.52) for inter-observer agreement. The motion palpation test used to assess VR asymmetry has low agreement levels; therefore, its clinical significance for measuring vertebral position is questionable.

Is there any relationship between range of motion, strength and position with health related quality of life and depression among women with postural kyphosis?

Purpose: The prevalence of osteoarthritis is higher among women. In post menopausal period both reduction in bone mineral density and osteoarthritis spesific symptoms may begin to appear. The breast size of the women is one of the major factor for kyphotic position. Reduction in bone mineral density and trunk misaligment, primarily affect thoracal vertebra position. Vertebral bone degeneration, depending on age, may make the deteriorated position permanent. This process not only affects muscular strength and range of motion but also affects daily life activities and quality of life. This study is conducted to investigate whether there is a relationship between flexibility, muscle strength, shoulder range of motion and quality of life with perception of depression. Methods: 19 women were recruited in the present study. The exclusion criteria included any psychiatric, neurological or musculoskeletal disorders except neck and upper back pain. At the begining, the volunteers were subjected to the assessment protocol which included demographic data (age, weight in kilograms and height in meters). Manuel muscle test was applied bilatteraly to the rhomboid muscle, trapez muscle, pectoral muscles, upper back erector spinae muscles by the same clinician. Range of motions of upper back and neck were assessed by using standard goniometer. In both, assessment measurements were done 3 times and medium values used. The Scapular symmetry and shoulder protraction was evaluated with measurement of acromion-wall distance, occiput-wall distance, T3-Spina Scapulae, T7- Inferior Angle of Scapulae. Patiens’s quality of life measured with SF-36 and depression with Beck Depression Inventory. After the data were collected analyzed with SPSS 21. Pearson’s correlation analysses test was used to investigate of correlations between the parameters were measured. The level of significance was set at p < 0.05. Results: The mean values of age and body mass index of the subjects were 32.16±8.09 years and 23.23±3.20 kg/m2, respectively. There was moderate correlation between right shoulder flexion and Social Function (SF) which is a subscale of SF-36 (r:0.500, p:0.029), left shoulder flexion and Social Function (SF) (r:0.600, p:0.007). There was moderate correlation between left shoulder flexion and Role Physical (RP) (r:0.523, p:0.022), Role Emotional (RE) (r:0.609, p:0.006) and Mental Component Summary (r:0.573, p:0.01), respectively. While there was significant correlation between left shoulder abduction and SF-36 General Health (GH) (r:0.614, p:0.05) and Social Function (SF) (r:0.584, p: 0.009), there was moderate correlation between right and left shoulder rotation and SF-36 Role Physical (RP) (r:0.456, p:0.049). There was moderately negative correlation between neck rightand left rotation and Beck Depression Inventory (r:-0.622, p:0.004) and significant correlation with SF-36 General Health (GH) (r:0.495, p: 0.031). The moderate and strong correlation between muscle strength and subscales of SF-36 with their correlation coefficient and p values were given in the table. The measurements that were conducted to determine the position and flexibility, there was moderately negative correlation between Acromion Wall Distance, SF-36 Role Physical (RP) (r:-0.616, p:0.005), Role Emotional (RE) (r:-0.622, p:0.004) and Mental Component Summary (r:-0.603, p:0.006). There was no correlation between other parameters of the study (p>0.005). Conclusions: According to the results of the present study, there was moderate towards strong correlation between anthropometric measurements, muscle strength and health related quality of life among women with postural kyphosis. The effects of the non-dominance extremity values on their quality of life of the subjects was one of the remarkable results of the present study. Subsequent to maintaining postural integrity by increasing muscular strength and range of motion, may bring about increase in health related quality of life among women suffering from postural kyphosis.Tabled 1Muscle StrengthM. RhomboideusM. TrapeziusM. PectoralisM. Erector SpinaeRLRLRLPhysical Function---r:0.466 p:0.044--r:0.461 p:0.047General Healthr:0.650 p:0.003r:0.650 p:0.003r:0.647 p:0.003r:0.711 p:0.001r:0.468 p:0.044r:0.468 p:0.044r:0.706 p:0.001Social Functionr:0.515 p:0.024r:0.515 p:0.024r:0.492 p:0.032r:0.631 p:0.004r:0.518 p:0.023r:0.518 p:0.023r:0.724 p:0.000Vitalityr:0.463 p:0.046r:0.463 p:0.046-r:0.409 p:0.004--r:0.507 p:0.027Physical Component Summaryr:0.519 p:0.023r:0.519 p:0.023-r:0.582 p:0.009--r:0.580 p:0.009 Open table in a new tab

Five- to eight-year course and prognosis of patellofemoral pain

Five- to eight-year course and prognosis of patellofemoral pain

Neural responses to the mechanical characteristics of high velocity, low amplitude spinal manipulation: Effect of specific contact site

BackgroundSystematic investigations are needed identifying how variability in the biomechanical characteristics of spinal manipulation affects physiological responses. Such knowledge may inform future clinical practice and research study design. ObjectiveTo determine how contact site for high velocity, low amplitude spinal manipulation (HVLA-SM) affects sensory input to the central nervous system. DesignHVLA-SM was applied to 4 specific anatomic locations using a no-HVLA-SM control at each location randomized in an 8×8 Latin square design in an animal model. MethodsNeural activity from muscle spindles in the multifidus and longissimus muscles were recorded from L6 dorsal rootlets in 16 anesthetized cats. A posterior to anterior HVLA-SM was applied through the intact skin overlying the L6 spinous process, lamina, inferior articular process and L7 spinous process. HVLA-SMs were preceded and followed by simulated spinal movement applied to the L6 vertebra. Change in mean instantaneous discharge frequency (ΔMIF) was determined during the thrust and the simulated spinal movement. ResultsAll contact sites increased L6 muscle spindle discharge during the thrust. Contact at all L6 sites significantly increased spindle discharge more than at the L7 site when recording at L6. There were no differences between L6 contact sites. For simulated movement, the L6 contact sites but not the L7 contact site significantly decreased L6 spindle responses to a change in vertebral position but not to movement to that position. ConclusionsThis animal study showed that contact site for an HVLA-SM can have a significant effect on the magnitude of sensory input arising from muscle spindles in the back.

Image-Guided Cryoablation of the Spine in a Swine Model: Clinical, Radiological, and Pathological Findings with Light and Electron Microscopy.

This study was designed to present the feasibility of an in vivo image-guided percutaneous cryoablation of the porcine vertebral body. The institutional animal care committee approved this study. Cone-beam computed tomography (CBCT)-guided vertebral cryoablations (n = 22) were performed in eight pigs with short, 2-min, single or double-freezing protocols. Protective measures to nerves included dioxide carbon (CO2) epidural injections and spinal canal temperature monitoring. Clinical, radiological, and pathological data with light (n = 20) or transmission electron (n = 2) microscopic analyses were evaluated after 6 days of clinical follow-up and euthanasia. CBCT/fluoroscopic-guided transpedicular vertebral body cryoprobe positioning and CO2 epidural injection were successful in all procedures. No major complications were observed in seven animals (87.5 %, n = 8). A minor complication was observed in one pig (12.5 %, n = 1). Logistic regression model analysis showed the cryoprobe-spinal canal (Cp-Sc) distance as the most efficient parameter to categorize spinal canal temperatures lower than 19 °C (p < 0.004), with a significant Pearson's correlation test (p < 0.041) between the Cp-Sc distance and the lowest spinal canal temperatures. Ablation zones encompassed pedicles and the posterior wall of the vertebral bodies with an inflammatory rim, although no inflammatory infiltrate was depicted in the surrounding neural structures at light microscopy. Ultrastructural analyses evidenced myelin sheath disruption in some large nerve fibers, although neurological deficits were not observed. CBCT-guided vertebral cryoablation of the porcine spine is feasible under a combination of a short freezing protocol and protective measures to the surrounding nerves. Ultrastructural analyses may be helpful assess the early modifications of the nerve fibers.

Evaluation of a Patient-Specific Finite-Element Model to Simulate Conservative Treatment in Adolescent Idiopathic Scoliosis

Study designRetrospective validation study. ObjectivesTo propose a method to evaluate, from a clinical standpoint, the ability of a finite-element model (FEM) of the trunk to simulate orthotic correction of spinal deformity and to apply it to validate a previously described FEM. Summary of background dataSeveral FEMs of the scoliotic spine have been described in the literature. These models can prove useful in understanding the mechanisms of scoliosis progression and in optimizing its treatment, but their validation has often been lacking or incomplete. MethodsThree-dimensional (3D) geometries of 10 patients before and during conservative treatment were reconstructed from biplanar radiographs. The effect of bracing was simulated by modeling displacements induced by the brace pads. Simulated clinical indices (Cobb angle, T1–T12 and T4–T12 kyphosis, L1–L5 lordosis, apical vertebral rotation, torsion, rib hump) and vertebral orientations and positions were compared to those measured in the patients' 3D geometries. ResultsErrors in clinical indices were of the same order of magnitude as the uncertainties due to 3D reconstruction; for instance, Cobb angle was simulated with a root mean square error of 5.7°, and rib hump error was 5.6°. Vertebral orientation was simulated with a root mean square error of 4.8° and vertebral position with an error of 2.5 mm. ConclusionsThe methodology proposed here allowed in-depth evaluation of subject-specific simulations, confirming that FEMs of the trunk have the potential to accurately simulate brace action. These promising results provide a basis for ongoing 3D model development, toward the design of more efficient orthoses.

Dynamic motion characteristics of the lower lumbar spine: implication to lumbar pathology and surgical treatment.

Many studies have reported on the segmental motion range of the lumbar spine using various in vitro and in vivo experimental designs. However, the in vivo weightbearing dynamic motion characteristics of the L4-5 and L5-S1 motion segments are still not clearly described in literature. This study investigated in vivo motion of the lumbar spine during a weight-lifting activity. Ten asymptomatic subjects (M/F: 5/5; age: 40-60 years) were recruited. The lumbar segment of each subject was MRI-scanned to construct 3D models of the L2-S1 vertebrae. The lumbar spine was then imaged using a dual fluoroscopic imaging system as the subject performed a weight-lifting activity from a lumbar flexion position (45°) to maximal extension position. The 3D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral positions along the motion path. The relative translations and rotations of each motion segment were analyzed. All vertebral motion segments, L2-3, L3-4, L4-5 and L5-S1, rotated similarly during the lifting motion. L4-5 showed the largest anterior-posterior (AP) translation with 2.9 ± 1.5 mm and was significantly larger than L5-S1 (p < 0.05). L5-S1 showed the largest proximal-distal (PD) translation with 2.8 ± 0.9 mm and was significantly larger than all other motion segments (p < 0.05). The lower lumbar motion segments L4-5 and L5-S1 showed larger AP and PD translations, respectively, than the higher vertebral motion segments during the weight-lifting motion. The data provide insight into the physiological motion characteristics of the lumbar spine and potential mechanical mechanisms of lumbar disease development.

In Vivo Cervical Facet Joint Capsule Deformation During Flexion–Extension

Nonrandomized controlled cohort. To characterize subaxial cervical facet joint kinematics and facet joint capsule (FJC) deformation during in vivo, dynamic flexion-extension. To assess the effect of single-level anterior arthrodesis on adjacent segment FJC deformation. The cervical facet joint has been identified as the most common source of neck pain, and it is thought to play a role in chronic neck pain related to whiplash injury. Our current knowledge of cervical facet joint kinematics is based on cadaveric mechanical testing. Fourteen asymptomatic controls and 9 C5-C6 arthrodesis patients performed full range of motion flexion-extension while biplane radiographs were collected at 30 Hz. A volumetric model-based tracking process determined 3-dimensional vertebral position with submillimeter accuracy. FJC fibers were modeled and grouped into anterior, lateral, posterior-lateral, posterior, and posterior-medial regions. FJC fiber deformations (total, shear, and compression-distraction) relative to the static position were determined for each cervical motion segment (C2-C3 through C6-C7) during flexion-extension. No significant differences in the rate of fiber deformation in flexion were identified among motion segments (P = 0.159); however, significant differences were observed among fiber regions (P < 0.001). Significant differences in the rate of fiber deformation in extension were identified among motion segments (P < 0.001) and among fiber regions (P = 0.001). The rate of FJC deformation in extension adjacent to the arthrodesis was 45% less than that in corresponding motion segments in control subjects (P = 0.001). In control subjects, FJC deformations are significantly different among vertebral levels and capsule regions when vertebrae are in an extended orientation. In a flexed orientation, FJC deformations are different only among capsule regions. Single-level anterior arthrodesis is associated with significantly less FJC deformation adjacent to the arthrodesis when the spine is in an extended orientation. 4.

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

BackgroundTo analyze the feasibility of active breath control (ABC), the lung tumor reproducibility and the rationale for single-breath-hold cone beam CT (CBCT)-guided hypofraction radiotherapy.MethodsSingle-breath-hold CBCT images were acquired using ABC in a cohort of 83 lung cancer patients (95 tumors) treated with hypofraction radiotherapy. For all alignments between the reference CT and CBCT images (including the pre-correction, post-correction and post-treatment CBCT images), the tumor reproducibility was evaluated via online manual alignment of the tumors, and the vertebral bone uncertainties were evaluated via offline manual alignment of the vertebral bones. The difference between the tumor reproducibility and the vertebral bone uncertainty represents the change in the tumor position relative to the vertebral bone. The relative tumor positions along the coronal, sagittal and transverse axes were measured based on the reference CT image. The correlations between the vertebral bone uncertainty, the relative tumor position, the total treatment time and the tumor reproducibility were evaluated using the Pearson correlations.ResultsPre-correction, the systematic/random errors of tumor reproducibility were 4.5/2.6 (medial-lateral, ML), 5.1/4.8 (cranial-caudal, CC) and 4.0/3.6 mm (anterior-posterior, AP). These errors were significantly decreased to within 3 mm, both post-correction and post-treatment. The corresponding PTV margins were 4.7 (ML), 7.4 (CC) and 5.4 (AP) mm. The changes in the tumor position relative to the vertebral bone displayed systematic/random errors of 2.2/2.0 (ML), 4.1/4.4 (CC) and 3.1/3.3 (AP) mm. The uncertainty of the vertebral bone significantly correlated to the reproducibility of the tumor position (P < 0.05), except in the CC direction post-treatment. However, no significant correlation was detected between the relative tumor position, the total treatment time and the tumor reproducibility (P > 0.05).ConclusionsUsing ABC for single-breath-hold CBCT guidance is an effective method to reduce the PTV margin of hypofraction radiotherapy for lung cancer. Using ABC, the tumor position was significantly altered relative to the vertebral position. The reproducibility of the tumor position was affected by the vertebral bone but not by the relative tumor position or the total treatment time.

Ontogenetic allometry in the thoracolumbar spine of mammal species with differing gait use

Vertebrae are serially homologous structures with tight integration through their evolution and development. However, in mammals, the thoracic and lumbar regions are morphologically and functionally differentiated. We test the hypothesis that locomotor specialization is associated with altered post-natal growth patterns in vertebrae from different vertebral regions. We use longitudinal data to examine thoracolumbar growth in two specialized half-bounding (Oryctolagus cuniculus and Chinchilla lanigera) and two non-specialized (Cavia porcellus and Monodelphis domestica) species with similar body sizes. Lateral X-rays of 38 individuals were the source of centrum length, centrum height and intervertebral space length measures for 19-20 thoracolumbar vertebrae. The repeated measurements design included the same individuals soon after birth and again at adult size. Data from columns with different vertebral counts were compared by either summing (length) or averaging (height) within regions, and individual vertebrae were directly compared at the first and last five vertebral positions. Specialized half-bounders had longer lumbar regions than generalists, which was attributable to positively allometric growth of the lumbar centra. Lumbar centrum length was more variable both ontogenetically and interspecifically than the other variables, suggesting heterochrony may be generating lumbar variation. Craniocaudal patterns of centrum growth correlate with expression of regionalizing genes (i.e., Hox).

X-Stop® Implantation Effectively Limits Segmental Lumbar Extension in-vivo without Altering the Kinematics of the Adjacent Levels.

To evaluate the in-vivo three-dimensional (3D) vertebral kinematics of the implanted and adjacent segments after implantation of the interspinous process distracting (ISP) device during various functional activities. Eight patients with lumbar spinal stenosis (LSS) scheduled for X-Stop® surgery were recruited. Prior to surgery, patients were scanned with computed tomography/ magnetic resonance imaging (CT/MRI) in order to construct 3D L2 to S1 vertebral models. The lumbar spines of the patients were then imaged using two fluoroscopes while they performed seven functional activities before and after X-Stop® surgeries. The in-vivo 3D vertebral positions were determined in the dual fluoroscopic images using an established 2D-3D matching method. The vertebral 3D ranges of motion (ROM) of the implanted and cranial-caudal adjacent levels were then measured. Primary ROMs of the implanted segments were significantly decreased (p < 0.05) by 50.2% only at torso extension, from preoperative 2.5 ± 1.4° to postoperative 1.1 ± 0.5°, but not significantly (p > 0.05) at flexion, twisting and lateral bending. Primary ROM and the coupled translations and rotations of the implanted and the adjacent levels were not significantly changed during each posture. X-Stop® implantation reduced the in-vivo range of extension by 50.2% at the implanted segment without disturbing 3D kinematics at the adjacent segments.

Continuous cervical spine kinematics during in vivo dynamic flexion-extension

Background contextA precise and comprehensive definition of “normal” in vivo cervical kinematics does not exist due to high intersubject variability and the absence of midrange kinematic data. In vitro test protocols and finite element models that are validated using only end range of motion data may not accurately reproduce continuous in vivo motion. PurposeThe primary objective of this study was to precisely quantify cervical spine intervertebral kinematics during continuous, functional flexion-extension in asymptomatic subjects. The advantages of assessing continuous intervertebral kinematics were demonstrated by comparing asymptomatic controls with patients with single-level anterior arthrodesis. Study designCervical spine kinematics were determined during continuous in vivo flexion-extension in a clinically relevant age group of asymptomatic controls and a group of patients with C5–C6 arthrodesis. Patient sampleThe patient sample consisted of 6 patients with single-level (C5–C6) anterior arthrodesis (average age: 48.8±6.9 years; 1 male, 5 female; 7.6±1.2 months postsurgery) and 18 asymptomatic control subjects of similar age (average age: 45.6±5.8 years; 5 male, 13 female). Outcome measuresOutcome measures included the physiologic measure of continuous kinematic motion paths at each cervical motion segment (C2–C7) during flexion-extension. MethodsParticipants performed flexion-extension while biplane radiographs were collected at 30 images per second. A previously validated tracking process determined three-dimensional vertebral positions with submillimeter accuracy. Continuous flexion-extension rotation and anterior-posterior translation motion paths were adjusted for disc height and static orientation of each corresponding motion segment. ResultsIntersubject variability in flexion-extension angle was decreased 15% to 46% and intersubject variability in anterior-posterior translation was reduced 14% to 33% after adjusting for disc height and static orientation angle. Average intersubject variability in continuous motion paths was 1.9° in flexion-extension and 0.6 mm in translation. Third-order polynomial equations were determined to precisely describe the continuous flexion-extension and anterior-posterior translation motion path at each motion segment (all R2>0.99). ConclusionsA significant portion of the intersubject variability in cervical kinematics can be explained by the disc height and the static orientation of each motion segment. Clinically relevant information may be gained by assessing intervertebral kinematics during continuous functional movement rather than at static, end range of motion positions. The fidelity of in vitro cervical spine mechanical testing protocols may be evaluated by comparing in vitro kinematics to the continuous motion paths presented.

Cambios en la posición de las estructuras esqueléticas del complejo cráneo-cervical posterior a una cirugía ortognática

The aim of the present study was to conduct research on presence of changes in skeletal structures’ position of the cervical-cranial complex after treatment involving orthognatic surgery. 30 patient files were reviewed. Patients were afflicted with initial class I, II and III malocclusions which had been treated with orthognathic surgery. With the help of lateral skull X-rays, measurements were taken of pre- and post-surgical positions of vertebrae, hyoid bone, as well as skull rotation. It was found that patients subjected to combined surgery presented greater range of skull rotation changes in a posterior direction (p = 0.006). Female patients presented tendency to posterior skull rotation, and exhibited distance decrease from atlas to skull base (p = 0.23). In surgical patients, it is important to timely identify these skull rotation changes since they might elicit relapse of performed orthognathic surgery and/or occipital headache.

Three-Dimensional Vertebral Wedging in Mild and Moderate Adolescent Idiopathic Scoliosis

BackgroundVertebral wedging is associated with spinal deformity progression in adolescent idiopathic scoliosis. Reporting frontal and sagittal wedging separately could be misleading since these are projected values of a single three-dimensional deformation of the vertebral body. The objectives of this study were to determine if three-dimensional vertebral body wedging is present in mild scoliosis and if there are a preferential vertebral level, position and plane of deformation with increasing scoliotic severity.MethodologyTwenty-seven adolescent idiopathic scoliotic girls with mild to moderate Cobb angles (10° to 50°) participated in this study. All subjects had at least one set of bi-planar radiographs taken with the EOS® X-ray imaging system prior to any treatment. Subjects were divided into two groups, separating the mild (under 20°) from the moderate (20° and over) spinal scoliotic deformities. Wedging was calculated in three different geometric planes with respect to the smallest edge of the vertebral body.ResultsFactorial analyses of variance revealed a main effect for the scoliosis severity but no main effect of vertebral Levels (apex and each of the three vertebrae above and below it) (F = 1.78, p = 0.101). Main effects of vertebral Positions (apex and above or below it) (F = 4.20, p = 0.015) and wedging Planes (F = 34.36, p<0.001) were also noted. Post-hoc analysis demonstrated a greater wedging in the inferior group of vertebrae (3.6°) than the superior group (2.9°, p = 0.019) and a significantly greater wedging (p≤0.03) along the sagittal plane (4.3°).ConclusionsVertebral wedging was present in mild scoliosis and increased as the scoliosis progressed. The greater wedging of the inferior group of vertebrae could be important in estimating the most distal vertebral segment to be restrained by bracing or to be fused in surgery. Largest vertebral body wedging values obtained in the sagittal plane support the claim that scoliosis could be initiated through a hypokyphosis.