Sagittal Curvature Research Articles

Sagittal femoral condylar shape varies along a continuum from spherical to ovoid: a systematic review and meta-analysis.

Considerable anatomic variations of sagittal femoral condylar shape have been reported, with a continuum between spherical (or single-radius) and ovoid (or multi-radius) condyles. The purpose of this systematic review and meta-analysis was to critically appraise and synthesise the available literature on the sagittal femoral profile. The hypothesis was that studies would reveal considerable variability among individuals, but also in their methodology to quantify sagittal profiles. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. On 10 September 2021 two authors searched for Level I to IV studies that reported on the sagittal curvature of the medial and/or lateral femoral condyles using the MEDLINE®, EMBASE® and Cochrane Library. Results were summarised by tabulating means, standard deviations and/or ranges for the reported radii-of-curvature, or ellipsoidal semi-major and semi-minor lengths of the condyles. To quantify sagittal 'ovoidicity' and asymmetry, results were stratified according to coordinate reference frame (posterior condylar axis (PCA), clinical and surgical transepicondylar axis (cTEA and sTEA), unified sagittal plane (USP), or unclear) and summarised in forest plots as standardised mean differences (SMD). Thirty-eight articles wereeligible for full text extraction, quantifyingsagittal radii-of-curvature by best-fit circles (BFC), ellipsoids, polynomials, spherical or cylindrical fitting. Studies with clear definition of the measurement plane revealed that both condyles were generally ovoid, with considerably greater 'ovoidicity' at the medial condyle (SMD, 4.09) versus the lateral condyle (SMD, 3.33). In addition, distal condylar radii were greater medially when measured normal to the TEA (cTEA: SMD, 0.81; sTEA: SMD, 0.79), but greater laterally when measured in a USP (SMD, -0.83). Posterior condylar radii were greater laterally when measured in a USP (SMD, -0.60). Studies reported considerable variability of sagittal femoral condylar radii-of-curvature, which arenot incremental, but rathera continuum that ranges from spherical to ovoid. Although this variation could be accommodated by single-, dual- and multi-radii femoral components, a surgeon typically uses only one or two TKA designs. Hence, there is a risk of mismatch between the native and prosthetic sagittal profile that could result in mid-flexion ligament imbalance unless other parameters are changed. These findings support the drive towards patient-specific implants to potentially achieve accurate sagittal bone-implant fit through implant customisation. IV.

The cervical sagittal curvature change in patients with or without PCSM after laminoplasty.

ObjectiveAfter laminoplasty, the cervical sagittal curvature of some patients tend to be lordotic, this phenomenon cannot be explained by the theory of laminoplasty, and the reason remains unknown. We explored the possible role played by pinching cervical spondylotic myelopathy (PCSM) in the cervical sagittal curvature change in patients after laminoplasty.MethodsFrom April 2017 to May 2019, we studied 122 patients undergoing laminoplasty with cervical spondylotic myelopathy (CSM). All patients were divided into Group A (anterior compression only, without PCSM) and Group B (both anterior and posterior compression, with PCSM). The visual analogue scale (VAS) was used to measure pain, and modified Japanese Orthopedic Association (mJOA) score was derived. The cervical global angle (CGA) and the range of cervical motion (ROM) were compared. The clinical and imaging results were compared between Group A and Group B.ResultsAfter laminoplasty, both the mean VAS and mJOA scores improved significantly in Group A and Group B, the mJOA recovery rate of Group B was better than that of Group A (P < 0.05). The mean CGA and ROM decreased in Group A, but increased in Group B. MRI revealed that the ligamentum flavum of Group A was significantly thinner than that of Group B (P < 0.05).ConclusionsBecause of the hypertrophic and folded ligamentum flavum compressing the dorsal spinal cord, patients with PCSM may maintain a compulsive kyphotic posture. After laminoplasty, the cervical sagittal curvature of these patients tend to be lordotic due to the release of dorsal spinal cord compression.

Contraindications to magnetically controlled growing rods: consensus among experts in treating early onset scoliosis.

The purpose of this study was to describe contraindications to the magnetically controlled growing rod (MCGR) in patients with early onset scoliosis (EOS) by establishing consensus amongst expert surgeons who treat these patients frequently. Nine pediatric spine surgeons from an international EOS study group participated in semi-structured interviews via email to identify factors that influence decision making in the use of MCGR. A 39-question survey was then developed to specify these factors as contraindications for MCGR-these included patient age and size, etiology, medical comorbidities, coronal and sagittal curve profiles, and skin and soft tissue characteristics. Pediatric spine surgeons from the EOS international study group were invited to complete the survey. A second 29-item survey was created to determine details and clarify results from the first survey. Responses were analyzed for consensus (> 70%), near consensus (60-69%), and no consensus/variability (< 60%) for MCGR contraindication. 56 surgeons of 173 invited (32%) completed the first survey, and 64 (37%) completed the second survey. Responders had a mean of over 15years in practice (range 1-45) with over 6years of experience with using MCGR (range 2-12). 71.4% of respondents agreed that patient size characteristics should be considered as contraindications, including BMI (81.3%) and spinal height (84.4%), although a specific BMI range or a specific minimum spinal height were not agreed upon. Among surgeons who agreed that skin and soft tissue problems were contraindications (78.6%), insufficient soft tissue (98%) and skin (89%) to cover MCGR were specified.Among surgeons who reported curve stiffness as a contraindication (85.9%), there was agreement that this curve stiffness should be defined by clinical evaluation (78.2%) and by traction films (72.3%). Among surgeons who reported sagittal curve characteristics as contraindications, hyperkyphosis (95.3%) and sagittal curve apex above T3 (70%) were specified. Surgeons who indicated the need for repetitive MRI as a contraindication (79.7%) agreed that image quality (72.9%) and not patient safety (13.6%) was the concern. In the entire cohort, consensus was not achieved on the following factors: patient age (57.4%),medical comorbidities (46.4%), etiology (53.6%),andcoronal curve characteristics (58.9%). Surgeon consensus suggests that MCGR should be avoided in patients who have insufficient spinal height to accommodate the MCGR, have potential skin and soft tissue inadequacy, have too stiff a spinal curve, have too much kyphosis, and require repetitive MRI, particularly of the spine. Future data-driven studies using this framework are warranted to generate more specific criteria (e.g. specific degrees of kyphosis) to facilitate clinical decision making for EOS patients. Level V-expert opinion.

Three-dimensional printing versus freehand surgical techniques in the surgical management of adolescent idiopathic spinal deformity.

Three-dimensional (3D) printed guides are finding increasing applications in the field of orthopaedic surgery and more recently spine surgery. This retrospective cohort study compares benefits and costs of 3D printed guides in surgical treatment of adolescent idiopathic scoliosis (AIS) compared to freehand techniques. Intraoperative screw placement was conducted either with 3D printed guides (3D cohort) or traditional freehand technique (freehand cohort) for AIS patients undergoing spinal fusion at a single institution. Patient and perioperative data include: screw placement time, length of surgery, blood loss, hospital stay, spinal curvature correction, total implant costs and training level of surgical assist. Multivariate analysis assessed for confounding and effect modification. P-values <0.05 were considered significant. There were 29 patients included in analyses, 18 in the 3D and 11 in the freehand (FH) cohort, for a total of 263 3D and 307 freehand screws. Between cohorts, there were no significant differences in patient age (P=0.93), gender (P=0.15), height (P=0.18) or weight (P=0.40). The 3D cohort (mean $26,215, SD =$6,374) had significantly higher implant costs than FH (mean $18,660, SD =$5,587, P=0.003) with significantly reduced intraoperative blood loss (mean 559 mL, SD =273 FH; vs. mean 357 mL, SD =123 3D; P=0.01). On multivariate analysis, surgical residents had significantly faster screw placement times when using 3D guides (P<0.001) than when placing screws freehand. There were no significant differences between cohorts in length of postoperative hospitalization, spinal levels fused, or coronal or sagittal curve correction. At significant cost, 3D printed guides reduce intraoperative blood loss compared to freehand pedicle screw placement and reduce screw placement time for surgical residents.

Local curvatures and its measurements of an optical surface or a wavefront: a review

The mathematical tools to calculate surface and wavefront local curvatures have been growing in importance because, when studying and evaluating some optical systems, the local curvature becomes extremely important. Many practical methods have been created to measure the wavefront shape and local curvatures as well as many mathematical tools to describe them. These methods are very useful in ophthalmology mainly for corneal evaluation, but the methods are now being used in other fields of optical metrology, especially in optical testing, interferometric wavefront description, and others. In some instruments and optical devices, mainly ophthalmic and optometric instruments, the local curvatures distribution over the pupil of an optical system is more important than the wavefront topography. A typical example is a human eye, in which corneal topographers, eye aberrometers, and several other instruments are used to measure the local curvatures. In particular, the main aspects of the curvature calculation at a given point for different slopes in any direction are introduced. The principal curvatures, mean, Gaussian, cylindrical, tangential, and sagittal curvatures are described. In the second part of this review, we describe the main methods and devices for wavefront sensing, measuring elevations, slopes, or curvatures. We conclude with a description of some methods to measure and calculate local curvatures from wavefront sensors by measuring the wavefront elevations, the transverse aberrations (slopes), or directly the curvatures.

Higher femoral anteversion restoration accuracy after total hip arthroplasty with a proximally fixed anatomic stem than with a generic straight double-tapered stem.

Femoral antetorsion in uncemented hip replacement hardly can be modified and the restoration of the anatomic anteversion might be difficult with standard stems. We compared femoral anteversion restoration of a generic straight stem with a proximally fixed anatomic stem that included a dual sagittal curvature and a proximal torsion. It was hypothesised that the restoration of the anteversion was more accurate with the anatomic stem. In this comparative study data were collected prospectively of 80 consecutive patients with total hip arthroplasty for primary osteoarthritis. In the first 40 patients (Group I) a cementless proximally fixed anatomic stem with 15° antetorsion of the shaft and a dual sagittal curvature was used. Its design was based on a database of 3D CT images of 600 hips. For comparison a cementless generic straight double-tapered stem was implanted in the next 40 patients (Group II). All operations were performed by one experienced surgeon. All patients had a preoperative 3D planning. A low-dose CT scan was performed at 3 months postoperatively to determine the postoperative stem anteversion. The demographics were similar in both groups. In group I the mean postoperative femoral anteversion was similar to the preoperative one (22.1° ± 10.2° vs. 20.4° ± 9°; p = 0.2). In Group II, the mean postoperative femoral anteversion was lower (12.9° ± 10.8°, vs. 18.3° ± 12°; p = 0.02). Uncemented standard femoral stems tend to reduce femoral anteversion. The used anatomic stem restored femoral anteversion better. The clinical impact of this finding has to be proven.

Mechanical Analysis of Posterior Pedicle Screw System Placement and Internal Fixation in the Treatment of Lumbar Fractures.

Objective Image segmentation technology is applied to separate a single vertebra from the three-dimensional model of the spine, so as to separate a single vertebra image with smaller error, higher degree of automation, and better results. The objectives are to study the biomechanical characteristics of posterior short-segment pedicle screw fixation by three-dimensional finite element method, analyze the mechanical characteristics of posterior pedicle screw rod fixation system under different factors, and demonstrate the feasibility of its application in the treatment of lumbar fracture. Methods The authors searched the database for articles about the treatment of lumbar spine fracture, screw rod internal fixation system, and its mechanical parameters. The threshold segmentation method based on region segmentation method was used to segment the image, and the three-dimensional finite element model was used to analyze the biomechanical characteristics of different posterior internal fixation for lumbar spine fracture. Results The posterior pedicle internal fixation system for the treatment of multilevel spinal fractures is a mature surgical technique and has fewer postoperative complications. Transpedicle fixation is effective and reliable. It can effectively restore the coronal and sagittal curvature of the vertebral body and restore the stability of the spine better. But the choice of internal fixation method should be individualized based on fracture type, identification of critical and secondary injury sites, and stability assessment. Only after mastering the biomechanical characteristics of the posterior screw rod system for the treatment of lumbar fracture, selecting the appropriate method, and fixing the appropriate movement unit can the best fixation be achieved. Conclusion Threshold method is the most direct and simple image segmentation method. The core technology of thresholding is the selection of threshold, which will affect the final segmentation effect. The most common segmentation method is to calculate the segmentation threshold by histogram. The threshold method has less computation and good segmentation effect for the image with large contrast between background and target. Posterior pedicle screw rod system internal fixation has the advantages of less trauma, good reduction, reliable fixation, and less complications. The design, placement angle and depth of various internal fixation systems, and the number of fixed segments all show different mechanical characteristics. As long as we master the above characteristics, choose the appropriate method and fix the appropriate motor unit, and we can get the best fixation; it can be used as an effective treatment for lumbar fracture.

Regional diaphragm motion analysis via dynamic MRI.

Breathing-related movement analysis is important in the study of many disease processes. The analysis of diaphragmatic motion via thoracic imaging in particular is important in a variety of disorders. Compared to computed tomography (CT) and fluoroscopy, dynamic magnetic resonance imaging (dMRI) has several advantages, such as better soft tissue contrast, no ionizing radiation, and greater flexibility in selecting scanning planes. In this paper, we propose a novel method for full diaphragmatic motion analysis via free-breathing dMRI. Firstly, after 4D dMRI image construction in a cohort of 51 normal children, we manually delineated the diaphragm on sagittal plane dMRI images at end-inspiration and end-expiration. Then, 25 points were selected uniformly and homologously on each hemi-diaphragm surface. Based on the inferior-superior displacements of these 25 points between end-expiration (EE) and end-inspiration (EI) time points, we obtained their velocities. We then summarized 13 parameters from these velocities for each hemi-diaphragm to provide a quantitative regional analysis of diaphragmatic motion. We observed that the regional velocities of the right hemi-diaphragm were almost always statistically significantly greater than those of the left hemi-diaphragm in homologous locations. There was a significant difference for sagittal curvatures but not for coronal curvatures between the two hemi-diaphragms. Using this methodology, future larger scale prospective studies may be considered to confirm our findings in the normal state and to quantitatively assess regional diaphragmatic dysfunction when various disease conditions are present.

Automatic recognition of whole-spine sagittal alignment and curvature analysis through a deep learning technique

PurposeArtificial intelligence based on deep learning (DL) approaches enables the automatic recognition of anatomic landmarks and subsequent estimation of various spinopelvic parameters. The locations of inflection points (IPs) and apices (APs) in whole-spine lateral radiographs could be mathematically determined by a fully automatic spinal sagittal curvature analysis system.MethodsWe developed a DL model for automatic spinal curvature analysis of whole-spine lateral plain radiographs by using 1800 annotated images of various spinal disease etiologies. The DL model comprised a landmark localizer to detect 25 vertebral landmarks and a numerical algorithm for the generation of an individualized spinal sagittal curvature. The characteristics of the spinal curvature, including the IPs, APs, and curvature angle, could thus be analyzed using mathematical definitions. The localization error of each landmark was calculated from the predictions of 300 test images to evaluate the performance of the landmark localizer. The interrater reliability among a senior orthopedic surgeon, a radiologist, and the DL model was assessed using the intraclass correlation coefficient (ICC).ResultsThe accuracy of the landmark localizer was within an acceptable range (median error: 1.7–4.1 mm), and the interrater reliabilities between the proposed DL model and each expert were good to excellent (all ICCs > 0.85) for the measurement of spinal curvature characteristics.ConclusionThe interrater reliability between the proposed DL model and human experts was good to excellent in predicting the locations of IPs, APs, and curvature angles. Future applications should be explored to validate this system and improve its clinical efficiency.

Surgical outcomes of severe spinal deformities exceeding 100° or treated by vertebral column resection (VCR). Does implant density matter?: an observational study of deformity groupings.

Prospective multicenter international observational study. To investigate the effect of implant density on clinical outcomes in complex pediatric spine reconstruction. Implant density in spine deformity surgery has been a subject of much debate with some authors advocating higher density for better correction. Few studies have looked at the effect of implant density on severe curves > 100 deg or treated with vertebral column resection (VCR). 250/311 pts with 2-year f/u enrolled in the FOX pediatric database from 17 international sites were queried for the impact of implant density and surgical outcomes. Patients were grouped into three implant density categories for comparative analysis Group 1 (density ≤ 1), Group 2 (1 < density < 1.5) and Group 3 (density; 1.5-2). 250 pts: 47 (Grp1)/99 (Grp2) /104 (Grp3); Pre-op age and etiology and curve types were similar in all groups, but body mass index (BMI) was higher in Grp3. Grps 1 and 2 had significantly higher sagittal deformity angular ratio (S-DAR) compared to Grp 3 (p < 0.001). Pre-op Halo Gravity Traction (HGT) was used in 55.3%/44.4%/31.7%, p = 0.017; Grp1/Grp2/Grp3, respectively. Average duration of surgery (min) was higher in Grp3 relative to Grp1 only: 352.5/456.5/515.0, p = 0.0029. Blood loss was similar in all Grps. Rate of VCR, PSO and SPO was similar in all Grps. Pre-op Coronal Cobb avg 96.1/83.6/88.6, p = 0.2342, attained similar correction after HGT (24.6%/27.2%/23.2%, p = 0.4864. Coronal Cobb corrections at 2-year follow-up (FU) were (37.1%/40.3%/53.5%, p = 0.0004). Pre-op sagittal Cobb was (105.4/101.9/75.9, p < 0.01.), achieved similar %correction in HGT (19.1%/22.3%/22.5%, p = 0.6851) and at 2-year FU (39.6%/41.4%/29.8%, p = 0.1916). After adjusting for C-DAR, S-DAR, pre-op coronal and sagittal Cobb, etiology, curve types, age, BMI and number of rods in multivariate analysis, the odds of developing post-operative implant complication was 11 times greater in group 1 compared to group 3 (OR = 11.17,95% CI 2.34-53.32). There was significant improvement in SRS scores in all Grps at 2-year FU. Although higher implant density was observed to be associated with greater curve correction and lower rates of post-operative implant-related complication and revision in heterogeneous case groups, the results may not imply causality of implant density on the outcomes in severe pediatric spine reconstruction.

Corneal Strain Induced by Intracorneal Ring Segment Implantation Visualized With Optical Coherence Elastography.

To record the axial strain field in the cornea directly after creating a stromal tunnel and implanting an intracorneal ring segment (ICRS). Freshly enucleated porcine eyes were obtained and assigned to either ICRS implantation, tunnel creation only, or virgin control groups. Immediately after manual tunnel creation and ICRS positioning, the entire eye globe was mounted on a customized holder and intraocular pressure (IOP) was adjusted to 15 mm Hg. Then, IOP was inreased to 20 mm Hg, in steps of 1 mm Hg. At each step, an optical coherence tomography volume scan was recorded. Displacements between subsequent scans were retrieved using a vector-based phase difference method. The induced corneal strain direction was determined by taking the axial gradient. In addition, corneal surface was detected and sagittal curvature maps computed. Corneal tissue presented a localized compressive strain in the direct vicinity of the stromal tunnel, which was independent of IOP change. The central and peripheral (exterior to the ICRS) cornea demonstrated compressive strains on IOP increase, and tensile strains on IOP decrease. ICRS implantation induced an annular-shaped tensile strain at its inner border, particularly during IOP increase. The compressive strains close to the tunnel remained after ICRS implantation. Corneal curvature changes were concentrated on regions where strain was induced. ICRS implantation induces localized strains in the regions subjected to refractive changes, suggesting that corneal strain and curvature are directly related. Studying corneal strain in response to surgical intervention may provide new insights on underlying working principles. [J Refract Surg. 2022;38(3):210-216.].

Do sagittal spinal curvature and back extensor endurance correlate with gait and balance measures in people with degenerative spinal conditions?

Do sagittal spinal curvature and back extensor endurance correlate with gait and balance measures in people with degenerative spinal conditions?

Sagittal imbalance of the spine is associated with poor sitting posture among primary and secondary school students in China: a cross-sectional study

BackgroundLong-term poor posture may affect the morphological development of the spine. However, there is no definite answer as to how writing posture affects students’ spine. This study attempted to compare the sagittal curvature of the spine between sitting and standing postures in adolescents to reveal the variation rule of spinal sagittal curvature of students with learning posture, and to discover the key factors that may affect students’ spinal health.Methods1138 participants (male, 604; female, 534; age range, 6–18 years) from three schools in Tianjin, China, including 570 primary school students and 568 secondary school students. This study used SpineScan and PA200 Station Posture Assessment System to assess the sagittal curvature of the spine for three postures: sitting on a chair in upright position, seated at a desk while reading/writing, and standing in natural relaxed position. Analyze the difference between spine angle of the three postures and the correlation between the sagittal plane angle of the spine and body posture.ResultsThe mean sagittal angle of the spine changed when the participants were in reading/writing position compared to standing position, with the lumbar lordosis angle significantly decreased (p < 0.05) and the thoracic kyphosis angle significantly increased (p < 0.05). The TKA and LLA angles were abnormal in 33 and 52% of students in reading/writing posture respectively. There was a significant correlation between sitting posture and standing spinal Angle and were positively correlated with the height of the teenager (p < 0.05). By contrast, a higher percentage of TKA and LLA subjects in the standard reading/writing posture reference range maintained normal spinal shape while standing.ConclusionsThe angle of thoracic kyphosis significantly increased from standing posture to upright sitting, reading/writing posture, while lumbar lordosis significantly decreased or even disappeared. There was a significant correlation between sagittal angle of spine in different postures. The poor sitting posture associated with sagittal angle abnormalities impact the shape of the spine such that sagittal imbalance was also observed when students in natural standing posture. Height is an important factor affecting the sitting spine shape of students.

Effects of plate contouring quality on the biomechanical performance of high tibial osteotomy fixation: A parametric finite element study.

Locking plates have threaded holes, in which threaded-head screws are affixed. Hence, they do not need to be in intimate contact with underlying bone to provide fixation. There are, however, reports that a large distance between the plate and the bone might cause clinical complications such as delayed union or nonunion, screw pull out, and screw and plate breakage. Considering the diversity in the capabilities and costs of different plate customization techniques, the purpose of this study was to investigate the effect of the plate contouring quality on the biomechanical performance of high tibial osteotomy (HTO) fixation. A finite element model of proximal tibia was developed in Abaqus, using the QCT data of a cadaver. The model was then subjected to open-wedge HTO (correction angle 12°) with TomoFix plate fixation. The sagittal curvature of the plate was changed parametrically to provide certain levels of geometrical fit, and the biomechanical performance parameters of fixation were assessed. Results indicated 5%, 9% and 38% increase in the stiffness of the construct, and the von Mises stress in the plate and locking screw just above the osteotomy site, respectively, when the level of fit of plate changed from 0% (initial non-contoured initial shape) to 100% (fully adapted shape). The same change decreased the pressure at the lateral hinge of the osteotomy by 61%, and the mean of the tensile stress on the screw shaft by 12%. It was concluded that the level of fit has conflicting effects on the biomechanical parameters of the HTO fixation system, that is, the structural stiffness, the pressure at the lateral hinge, the stresses in the plate and screws, and the pull out resistance of the screws. In particular, for HTO patients with high quality bone, the optimal level of fit should provide a tradeoff between these parameters.

Early Clinical Improvement of the Axial Pain after Sagittal Curve Restoration in Patients Who Underwent a Multiple Level Microdiscectomy with Fusion of the Cervical Spine Using Zero Profile Cages

A common pathology that causes axial and/or radicular pain is cervical degenerative spine. It has the potential to cause myelopathy. The majority of cases necessitate surgical decompression and sagittal balance correction; surgery may be performed at multiple levels of the cervical spine. Typically, during decompression, the degenerated discs are replaced and the spine is fused, and it has been recommended to restore the lordotic curve during the procedure to avoid any axial pain post-operatively. We followed our patients who had multiple level cervical spine decompression with fusion and monitored their axial pain after correction or in the absence of correction of the normal lordosis in the early post-operative period. When various levels of degenerative cervical spine are treated, it appears that axial pain does not improve in the immediate or early postoperative term.

Four-Dimensional Anatomical Spinal Reconstruction in Thoracic Adolescent Idiopathic Scoliosis.

Background:Recent surgical techniques involve 3-dimensional (3D) deformity correction of adolescent idiopathic scoliosis (AIS)1-4. However, next-generation surgical strategies should ensure that the final corrected spine is not only “non-scoliotic,” but has an anatomically correct shape. We developed a 4D anatomical spinal reconstruction technique that involves the use of spatiotemporal deformity prediction to preoperatively calculate the postoperative apex of thoracic kyphosis in order to achieve an anatomically correct spinal curvature5-7.Description:During the technique, facetectomies are performed at all levels except the lowest instrumented level in order to avoid pseudarthrosis at that site. Two rods are identically bent according to the desired postoperative anatomical thoracic kyphosis, with the apex often anticipated to be between T6 and T85-7. Two different categories of spinal rod shapes have been created to cover all presenting anatomies. The single-curve rod is utilized when the lowest instrumented vertebra is L1 or above and the thoracolumbar region remains straight. The double-curve rod is utilized when the lowest instrumented vertebra is L2 or L3. With both rod types, the cranial apex is created. There are 11 shapes of pre-bent, notch-free, cobalt-chromium alloy rods available in Japan7-9. Once the 2 spinal rods are connected to all polyaxial screw heads, the rods are simultaneously rotated1,2,5,7.Alternatives:Typical thoracic AIS exhibits thoracic hypokyphosis. Therefore, correction of the thoracic kyphosis and adjustment of the main thoracic curve are the 2 most important surgical goals for achieving an anatomically correct spine. Furthermore, hypokyphosis of the thoracic spine secondary to pedicle screw instrumentations can be reduced or prevented by utilizing the posterior-approach surgical strategies that we have previously described1-4.Rationale:In a healthy human population, the apex of the thoracic kyphosis is normally located at T6 to T8 as viewed on viewing standing sagittal radiographs10. However, for some patients with AIS, the postoperative apex of the thoracic kyphosis is almost identical to the apex of the preoperative thoracic scoliosis5, which is not anatomically correct. This insufficient correction is often a result of the spinal rods being bent to match the curvature of the scoliosis5. In addition, about 70% of cases of thoracic AIS do not have identical preoperative apices of the main thoracic scoliosis and thoracic kyphosis, and about 33% of cases have the apex of the scoliosis at the lower thoracic spine (i.e., T10 and T11)5. Performing sufficient multilevel facetectomies and utilizing the proper spinal rod curvature have been reported to greatly improve postoperative sagittal curve correction11-13. This proposed technique could be especially helpful in cases in which the apex of scoliosis is located in the lower thoracic spine, which is often seen in patients with Lenke 1AR scoliosis14.Expected Outcomes:When performed with proper shaping of the spinal rods and multilevel facetectomies, the present technique is expected to result in an anatomically correct thoracic spine. The use of this technique has been reported to increase the proportion of patients with a thoracic kyphosis apex at T6 to T8, from 51.3% preoperatively to 87.2% postoperatively5. Furthermore, patients who underwent this procedure with notch-free, pre-bent rods had a significantly higher postoperative thoracic kyphosis than patients who underwent the procedure with conventional, manually bent rods7.Important Tips: Mobilization of the spine by releasing the facet joints is more important than using a rigid implant.Two rods are bent identically to the desired postoperative anatomical thoracic kyphosis; the bending is not based on the preoperative scoliosis spinal curvature.This technique is applicable for Lenke 1, 1AR, and 2 through 6 curves except for Lenke 5 curves. However, the technique for producing pre-bent rods can also be utilized for Lenke 5 curves because the initial configuration leads to sagittal alignment of the spine. Acronyms & Abbreviations: TL/L = thoracolumbar/lumbarUIV = upper instrumented vertebraUEV = upper end vertebraSD = standard deviation

A Hybrid Deep Learning Construct for Detecting Keratoconus From Corneal Maps.

PurposeTo develop and assess the accuracy of a hybrid deep learning construct for detecting keratoconus (KCN) based on corneal topographic maps.MethodsWe collected 3794 corneal images from 542 eyes of 280 subjects and developed seven deep learning models based on anterior and posterior eccentricity, anterior and posterior elevation, anterior and posterior sagittal curvature, and corneal thickness maps to extract deep corneal features. An independent subset with 1050 images collected from 150 eyes of 85 subjects from a separate center was used to validate models. We developed a hybrid deep learning model to detect KCN. We visualized deep features of corneal parameters to assess the quality of learning subjectively and computed area under the receiver operating characteristic curve (AUC), confusion matrices, accuracy, and F1 score to evaluate models objectively.ResultsIn the development dataset, 204 eyes were normal, 123 eyes were suspected KCN, and 215 eyes had KCN. In the independent validation dataset, 50 eyes were normal, 50 eyes were suspected KCN, and 50 eyes were KCN. Images were annotated by three corneal specialists. The AUC of the models for the two-class and three-class problems based on the development set were 0.99 and 0.93, respectively.ConclusionsThe hybrid deep learning model achieved high accuracy in identifying KCN based on corneal maps and provided a time-efficient framework with low computational complexity.Translational RelevanceDeep learning can detect KCN from non-invasive corneal images with high accuracy, suggesting potential application in research and clinical practice to identify KCN.

The Sagittal Integral Morphotype in Male and Female Rowers.

The goal of this study was to describe the integrated spinal assessment of the sagittal morphotype in rowers to determine whether the intense practice of rowing causes a modification of the sagittal curvatures of the spine, its relationship with the rowing technique, and training background. The second goal was to analyse how the dorsal and lumbar curves behave in the three phases of the rowing gesture, and to determine which phases can be detrimental to the correct development of the spine during growth. We analysed the spine curvatures in the sagittal plane of 29 females and 82 males, which were measured with an inclinometer in standing, slump sitting, maximal trunk flexion and during rowing performance. The average value of thoracic kyphosis in the rowers was 30° (mean, 30 + 8.27°). Thoracic hyperkyphosis was found in only two rowers (1.8%). Lumbar lordosis was within normal range in 84.1% of the males (mean, 27 + 9.57°) and 75.9% of female rowers (mean, 33°). Functional thoracic hyperkyphosis was observed in 57.4% of the males and 17.1% of the females. Functional lumbar hyperkyphosis was observed in 28 of the 69 males (40.5%) and five of 22 females (17.2%). Rowing seems to provide adequate spine alignment in the sagittal plane on standing. The integrated spinal assessment of the sagittal morphotype showed that half or our rowers presented with functional thoracic hyperkyphosis, and 43.2% presented with functional lumbar hyperkyphosis. Spine behaviour during the rowing technique shows that the thoracic kyphosis (98.2%) and lumbar spine (91%) perform within normative ranges and could explain the adequate positioning of the spine in the sagittal plane on standing. Years of rowing training tend to reduce thoracic kyphosis in males.

Assessment of Pelvic Incidence Angle in Normal Indian Population and Spondylolisthesis

There is increasing emphasis on the sagittal spino-pelvic alignment and its interpretation is of critical importance in the management of spinal disorders. The vertebral column shows a vital role in the funding and locomotion of the human body. The judgment of normality can be made possible by analyzing the normal patterns of sagittal curvature and characteristics of each pattern of sagittal curvatures. In our study the control group which comprised of 50 healthy volunteers exhibited a minimum pelvic incidence of 33° and a maximum of 60° with an average of 50.12°. The minimum pelvic incidence in the study group was 42° and the maximum was 75°.The average pelvic incidence in the low grade listhesis group was 57.78° and in the high grade listhesis group it was 64.75°.The combined average of pelvic incidence angle in the study group was 58.34°and only one patient had a Pelvic incidence Angle of 75 degrees and the remaining three were only one patient had a Pelvic incidence Angle of 75 degrees and the remaining three were below 65 degrees. The objective of this study is to observe the parameters of sagittal and spino-pelvic balance in a sample of the Indian population consisting of volunteer asymptomatic individuals.

The utility of measures of anterior segment parameters of a Pentacam Scheimpflug tomographer in discriminating high myopic astigmatism from keratoconus.

The study aimed to evaluate and compare anterior segment parameters between keratoconic eyes and eyes with high myopic astigmatism using Pentacam Scheimpflug tomography. This was a retrospective cross-sectional study that included sixty keratoconic eyes (thirty-two persons) and seventy-three eyes (forty-six persons) with high myopic astigmatism with mean ages 24.72 ± 11.65years and 26.60 ± 10.69years, respectively. Twenty-three parameters from the topographic map and fifteen parameters from the Belin-Ambrosió enhanced ectasia display map of the printouts of a Scheimpflug principle-based Pentacam tomographer were evaluated for their diagnostic accuracy using Receiver Operating Characteristic (ROC) curve. All parameters except cornea volume, anterior chamber volume, and anterior chamber angle indicated a significant difference between high myopic astigmatism and keratoconic eyes. The area under the receiver operating characteristic (AUROC) of eighteen Pentacam parameters was excellent (0.9-1.0) in discriminating keratoconus from high myopic astigmatism, out of which four {anterior minimum sagittal curvature (ant. Rmin), posterior minimum sagittal curvature (post. Rmin), maximum Ambrosió relational thickness (ART max) and total deviation value (D)} indicated excellent (>90%) sensitivity and specificity in addition to the excellent AUROC values. Topographic and Belin-Ambrosió enhanced ectasia display (BAD) maps of a Scheimpflug principle-based Pentacam tomographer are useful in enhancing the diagnosis of keratoconus and may also provide valuable information in effectively screening for keratoconus cases among refractive surgery candidates with high myopic astigmatism.