Novel Surface Topographic Assessment of Lung Volume and Pulmonary Function Tests in Idiopathic Scoliosis: A Preliminary Study.

OBJECTIVE: Severe spinal deformity results in restrictive pulmonary disease from thoracic distortions and lung-volume limitations. Though spirometry and body plethysmography are widely accepted tests for pulmonary function tests (PFTs), they are time-consuming and require patient compliance. This study investigates whether surface topographic [surface topography (ST)] measurements of body volume difference (BVD) and torso volume difference between maximum inhale and exhale correlate to values determined on PFTs. METHODS: This study included patients with idiopathic scoliosis and thoracic/thoracolumbar curves ≥40 degrees. Patients received ST scans, clinical examinations, and EOS biplanar radiographs on the same day. PFTs were performed within 3 months of ST/radiographic analysis. Univariate linear regression analysis was used to examine relationships between BVD, PFT values, and mean curves. RESULTS: Sixteen patients (14.6 ± 2.2 y, 69% females) with idiopathic scoliosis and mean thoracic/thoracolumbar curves of 62 degrees ± 15˚ degrees (45 degrees to 93 degrees) were assessed. BVD displayed statistically high-positive positive correlations with forced vital capacity ( R = 0.863, P < 0.0001), forced expiratory volume in 1 second ( R = 0.870, P < 0.001), vital capacity ( R = 0.802, P < 0.0001), and TLC ( R = 0.831, P < 0.0001. Torso volume difference showed similarly high positive correlations to forced vital capacity, forced expiratory volume in 1 second, vital capacity, and TLC, but not residual volume. No correlations emerged between the mean thoracic/thoracolumbar curve and BVD or PFT values. CONCLUSION: This study strongly endorses further investigation into ST scanning as an alternative to traditional PFTs for assessing pulmonary volumes. The noncontact and noninvasive nature of ST scanning presents a valuable alternative method for analyzing thoracic volume, particularly beneficial for patients unable to cooperate with standard PFTs. LEVEL OF EVIDENCE: Level II-prognostic.

Exploring Correlations Between Pain and Deformity in Idiopathic Scoliosis With Validated Self-reported Pain Scores, Radiographic Measurements, and Trunk Surface Topographic Measurements.

BACKGROUND: Up to 75% of patients with idiopathic scoliosis (IS) report back pain, but the exact contributors are unclear. This study seeks to assess how pain correlates with demographics, radiographic and surface topographic (ST) measurements, and patient-reported outcome measures (PROMs) in patients with IS. METHODS: Patient-Reported Outcome Measurement Information System (PROMIS) Pain Interference (PI) and Scoliosis Research Society revised (SRS-22r) pain domain from an IRB approved prospectively collected registry containing patients 11 to 21 years old with IS were correlated (Spearman coefficients) with measurements from whole-body EOS radiography and ST scanning, PROMIS 1.0 PROMs, Trunk Appearance Perception Scale (TAPS), and SRS-22r domains. SRS-22r and PROMIS-PI were also compared between different sex, scoliosis severities, and primary curve locations with Mann-Whitney U or Kruskal-Wallis tests, and if significant differences were found, included with the 5 highest univariate correlated variables into stepwise multivariate linear regression models ( P <0.05 to enter, P >0.1 to remove) predicting SRS-22r pain and PROMIS-PI. RESULTS: One hundred and forty-nine patients (14.5 ± 2.0 y, body mass index 20.6 ± 4.1 kg/m 2 , 96 (64%) female, mean major coronal curve 40 ± 19 deg, range: 10 deg, 83 deg) reported mean PROMIS-PI of 42.2 ± 10.0 and SRS-22r pain of 4.4 ± 0.6. SRS-22r self-image was the most correlated variable with both SRS-22r pain (rho=0.519) and PROMIS-PI (rho=-0.594). Five variables, none of which were ST or radiographic measures, strongly predicted SRS pain domain (R=0.711, R2=0.505, N=138). Two variables (SRS-22r self-image and SRS-22r function) were utilized by a model correlated with PROMIS-PI (R=0.687, R2=0.463, N=124). CONCLUSIONS: SRS-22r function and self-image domains were more strongly correlated with SRS-22r pain and PROMIS-PI than any radiographic or ST measurements. LEVEL OF EVIDENCE: Level II-retrospective study.

A model microfluidics-based system for the human and mouse retina.

The application of microfluidics technologies to the study of retinal function and response holds great promise for development of new and improved treatments for patients with degenerative retinal diseases. Restoration of vision via retinal transplantation therapy has been severely limited by the low numbers of motile cells observed post transplantation. Using modern soft lithographic techniques, we have developed the µRetina, a novel and convenient biomimetic microfluidics device capable of examing the migratory behavior of retinal lineage cells within biomimetic geometries of the human and mouse retina. Coupled computer simulations and experimental validations were used to characterize and confirm the formation of chemical concentration gradients within the µRetina, while real-time images within the device captured radial and theta cell migration in response to concentration gradients of stromal derived factor (SDF-1), a known chemoattractant. Our data underscore how the µRetina can be used to examine the concentration-dependent migration of retinal progenitors in order to enhance current therapies, as well as develop novel migration-targeted treatments.

Fully automated determination of robotic pedicle screw accuracy and precision utilizing computer vision algorithms.

Historically, pedicle screw accuracy measurements have relied on CT and expert visual assessment of the position of pedicle screws relative to preoperative plans. Proper pedicle screw placement is necessary to avoid complications, cost and morbidity of revision procedures. The aim of this study was to determine accuracy and precision of pedicle screw insertion via a novel computer vision algorithm using preoperative and postoperative computed tomography (CT) scans. Three cadaveric specimens were utilized. Screw placement planning on preoperative CT was performed according to standard clinical practice. Two experienced surgeons performed bilateral T2-L4 instrumentation using robotic-assisted navigation. Postoperative CT scans of the instrumented levels were obtained. Automated segmentation and computer vision techniques were employed to align each preoperative vertebra with its postoperative counterpart and then compare screw positions along all three axes. Registration accuracy was assessed by preoperatively embedding spherical markers (tantalum beads) to measure discrepancies in landmark alignment. Eighty-eight pedicle screws were placed in 3 cadavers' spines. Automated registrations between pre- and postoperative CT achieved sub-voxel accuracy. For the screw tip and tail, the mean three-dimensional errors were 1.67 mm and 1.78 mm, respectively. Mean angular deviation of screw axes from plan was 1.58°. For screw mid-pedicular accuracy, mean absolute error in the medial-lateral and superior-inferior directions were 0.75 mm and 0.60 mm, respectively. This study introduces automated algorithms for determining accuracy and precision of planned pedicle screws. Our accuracy outcomes are comparable or superior to recent robotic-assisted in vivo and cadaver studies. This computerized workflow establishes a standardized protocol for assessing pedicle screw placement accuracy and precision and provides detailed 3D translational and angular accuracy and precision for baseline comparison.

The Longitudinal Effects of Posterior Spinal Fusion with Derotation on Axial Deformity in Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To characterize the change in angle of trunk rotation (ATR), axial vertebral rotation (AVR), and body surface rotation (BSR) in patients with adolescent idiopathic scoliosis (AIS) undergoing posterior spinal fusion (PSF) with en-bloc derotation across multiple postoperative visits. SUMMARY OF BACKGROUND DATA: Previous research has documented ATR, AVR, and BSR correction for AIS patients after surgery. However, there is a lack of evidence on the sustainability of this correction over time. METHODS: This was a retrospective study from a single-center prospective surface topographic registry of patients with AIS, age 11-20 at time of surgery, who underwent PSF with en-bloc derotation. Patients with previous spine surgery were excluded. ATR was measured with a scoliometer, AVR through EOS radiographic imaging, and BSR via surface topographic scanning, Data collection occurred at: preoperative, six-week, three-month, six-month, one-year, and two-year postoperative visits. BSR and AVR were tracked at the preoperative apical vertebral level, and the level with maximum deformity, at each respective timepoint. Generalized estimating equations models were used for statistical analysis. Covariates included age, sex, and body mass index. RESULTS: 49 patients (73.4% female, mean age 14.6±2.2 years, mean preoperative coronal curve angle 57.9°±8.5, and 67% major thoracic) were evaluated. ATR correction was significantly improved at all postoperative timepoints and there was no significant loss of correction. AVR Max and AVR Apex were significantly improved at all timepoints but there was a significant loss of correction for AVR Apex between the six-week and one-year visit (P=0.032). BSR Max achieved significant improvement at the three-month visit. BSR Apex was significantly improved at the three-month and one-year visit. CONCLUSION: ATR and AVR demonstrated significant axial plane correction at two-years postoperative in patients undergoing PSF for AIS. BSR did not maintain significant improvement by the two-year visit.

3D surface topographic measurements for idiopathic scoliosis are highly correlative to patient self-image questionnaires.

PURPOSE: Adolescent idiopathic scoliosis (AIS) is a deformity of the spine that results in external asymmetry of the torso in the shoulder, waist, and rib hump. Several patient reported outcome measures (PROMS) including the Trunk Appearance Perception Scale (TAPS) and SRS-22r self-image domain are used to measure the patient's self-perception. The purpose of this study is to investigate the relationship between objective surface topographic measurements of the torso to subjective patient self-perception. METHODS: 131 AIS subjects and 37 controls participated in this study. All subjects completed TAPS and SRS-22r PROMS followed by whole body 3d surface topographic scanning. An automated analysis pipeline was used to compute 57 measurements. Multivariate linear models were developed to predict TAPS and SRS-22r self-image using each unique combination of 3 parameters and leave one out validation where the best combinations were selected. RESULTS: Back surface rotation, waist crease vertical asymmetry and rib prominence volume were most predictive of TAPS. The final predicted TAPS values from leave one out cross validation was correlated to ground truth TAPS scores with an R value of 0.65. Back surface rotation, silhouette centroid deviation, and shoulder normal asymmetry were most predictive of SRS-22r self-image with a correlation of R = 0.48. CONCLUSION: Surface topographic measurements of the torso are correlated to TAPS and SRS-22r self-image scores in AIS patients and controls, with TAPS exhibiting a stronger relationship, better reflecting the patient's external asymmetries.

Reliability of automated topographic measurements for spine deformity.

PURPOSE: This study introduces a novel surface-topographic scanning system capable of automatically generating a suite of objective measurements to characterize torso shape. RESEARCH QUESTION: what is the reliability of the proposed system for measurement of trunk alignment parameters in patients with adolescent idiopathic scoliosis (AIS) and controls? METHODS: Forty-six adolescents (26 with AIS and 20 controls) were recruited for a prospective reliability study. A series of angular, volumetric, and area measures were computed from topographic scans in each of three clinically relevant poses using a fully automated processing pipeline. Intraclass correlation coefficients (ICC(2,1)) were computed within (intra-) and between (inter-) raters. Measurements were also performed on a torso phantom. RESULTS: Topographic measurements computed on a phantom were highly accurate (mean RMS error 1.7%) compared with CT. For human subjects, intra- and inter-rater reliability were both high (average ICC > 0.90) with intrinsic (pose-independent) measurements having near-perfect reliability (average ICC > 0.98). CONCLUSION: The proposed system is a suitable tool for topographic analysis of AIS; topographic measurements offer an objective description of torso shape that may complement other imaging modalities. Further research is needed to compare topographic findings with gold standard imaging of spinal alignment, e.g., standing radiography. CONCLUSION: clinical parameters can be reliably measured in a fully automated system, paving the way for objective analysis of symmetry, body shape pre/post-surgery, and tracking of pathology without ionizing radiation.

The Effects of Adolescent Idiopathic Scoliosis on Axial Rotation of the Spine: A Study of Twisting Using Surface Topography.

Axial twisting of the spine has been previously shown to be affected by scoliosis with decreased motion and asymmetric twisting. Existing methods for evaluating twisting may be cumbersome, unreliable, or require radiation exposure. In this study, we present an automated surface topographic measurement tool to evaluate global axial rotation of the spine, along with two measurements: twisting range of motion (TROM) and twisting asymmetry index (TASI). The aim of this study is to evaluate the impact of scoliosis on axial range of motion. Adolescent idiopathic scoliosis (AIS) patients and asymptomatic controls were scanned in a topographic scanner while twisting maximally to the left and right. TROM was significantly lower for AIS patients compared to control patients (69.1° vs. 78.5°, p = 0.020). TASI was significantly higher for AIS patients compared to control patients (29.6 vs. 19.8, p = 0.023). After stratifying by scoliosis severity, both TROM and TASI were significantly different only between control and severe scoliosis patients (Cobb angle > 40°). AIS patients were then divided by their major curve region (thoracic, thoracolumbar, or lumbar). ANOVA and post hoc tests showed that only TROM is significantly different between thoracic AIS patients and control patients. Thus, we demonstrate that surface topographic scanning can be used to evaluate twisting in AIS patients.

3D Surface Topographic Optical Scans Yield Highly Reliable Global Spine Range of Motion Measurements in Scoliotic and Non-Scoliotic Adolescents.

Background: Adolescent idiopathic scoliosis results in three dimensional changes to a patient's body, which may change a patient's range of motion. Surface topography is an emerging technology to evaluate three dimensional parameters in patients with scoliosis. The goal of this paper is to introduce novel and reliable surface topographic measurements for the assessment of global coronal and sagittal range of motion of the spine in adolescents, and to determine if these measurements can distinguish between adolescents with lumbar scoliosis and those without scoliosis. Methods: This study is a retrospective cohort study of a prospectively collected registry. Using a surface topographic scanner, a finger to floor and lateral bending scans were performed on each subject. Inter- and intra-rater reliabilities were assessed for each measurement. ANOVA analysis was used to test comparative hypotheses. Results: Inter-rater reliability for lateral bending fingertip asymmetry (LBFA) and lateral bending acromia asymmetry (LBAA) displayed poor reliability, while the coronal angle asymmetry (CAA), coronal angle range of motion (CAR), forward bending finger to floor (FBFF), forward bending acromia to floor (FBAF), sagittal angle (SA), and sagittal angle normalized (SAN) demonstrated good to excellent reliability. There was a significant difference between controls and lumbar scoliosis patients for LBFA, LBAA, CAA and FBAF (p-values < 0.01). Conclusion: Surface topography yields a reliable and rapid process for measuring global spine range of motion in the coronal and sagittal planes. Using these tools, there was a significant difference in measurements between patients with lumbar scoliosis and controls. In the future, we hope to be able to assess and predict perioperative spinal mobility changes.

Collective adhesion and displacement of retinal progenitor cells upon extracellular matrix substrates of transplantable biomaterials.

Strategies to replace retinal photoreceptors lost to damage or disease rely upon the migration of replacement cells transplanted into sub-retinal spaces. A significant obstacle to the advancement of cell transplantation for retinal repair is the limited migration of transplanted cells into host retina. In this work, we examine the adhesion and displacement responses of retinal progenitor cells on extracellular matrix substrates found in retina as well as widely used in the design and preparation of transplantable scaffolds. The data illustrate that retinal progenitor cells exhibit unique adhesive and displacement dynamics in response to poly-l-lysine, fibronectin, laminin, hyaluronic acid, and Matrigel. These findings suggest that transplantable biomaterials can be designed to improve cell integration by incorporating extracellular matrix substrates that affect the migratory behaviors of replacement cells.

In vitro formation of neuroclusters in microfluidic devices and cell migration as a function of stromal-derived growth factor 1 gradients.

Central nervous system (CNS) cells cultured in vitro as neuroclusters are useful models of tissue regeneration and disease progression. However, the role of cluster formation and collective migration of these neuroclusters to external stimuli has been largely unstudied in vitro. Here, 3 distinct CNS cell types, medulloblastoma (MB), medulloblastoma-derived glial progenitor cells (MGPC), and retinal progenitor cells (RPC), were examined with respect to cluster formation and migration in response to Stromal-Derived Growth Factor (SDF-1). A microfluidic platform was used to distinguish collective migration of neuroclusters from that of individual cells in response to controlled concentration profiles of SDF-1. Cell lines were also compared with respect to expression of CXCR4, the receptor for SDF-1, and the gap junction protein Connexin 43 (Cx43). All cell types spontaneously formed clusters and expressed both CXCR4 and Cx43. RPC clusters exhibited collective chemotactic migration (i.e. movement as clusters) along SDF-1 concentration gradients. MGPCs clusters did not exhibit adhesion-based migration, and migration of MB clusters was inconsistent. This study demonstrates how controlled microenvironments can be used to examine the formation and collective migration of CNS-derived neuroclusters in varied cell populations.