Global Sagittal Angle and T9-tilt seem to be the most clinically and functionally relevant global alignment parameters in patients with Adult Spinal Deformity.

Introduction: Radiographic analysis is necessary for the assessment and the surgical planning in adults with spinal deformity (ASD). Restoration of global alignment is key to improving patient's quality of life. However, the large number of existing global alignment parameters can be confusing for surgeons. Research question: To determine the most clinically and functionally relevant global alignment parameters in ASD. Material and methods: ASD and controls underwent full body biplanar X-ray to calculate global alignment parameters: odontoid to hip axis angle (OD-HA), global sagittal angle (GSA), global tilt (GT), SVA, center of auditory meatus to hip axis (CAM-HA), SSA, T1-tilt and T9-tilt. All subjects filled HRQoL questionnaires: ODI, SF-36, VAS for pain and BDI (Beck's Depression Inventory). 3D gait analysis was performed to calculate kinematic and spatio-temporal parameters. A machine learning model predicted gait parameters and HRQoL scores from global alignment parameters. Results: 124 primary ASD and 47 controls were enrolled. T9 tilt predicted the most BDI (31%), hip flexion/extension during gait (36%), and double support time (39%). GSA predicted the most ODI (26%), thorax flexion/extension during gait (33%), and cadence (36%). Discussion and conclusion: Among all global alignment parameters, GSA, evaluating both trunk shift and knee flexion, and T9 tilt, evaluating the shift of the center of mass, were the best predictors for most of HRQoL scores and gait kinematics. Therefore, we recommend using GSA and T9 tilt in clinical practice when evaluating ASD because they represent the most quality of life and functional kinematic of these patients.

Kinematic adaptations from self-selected to fast speed walking in patients with adult spinal deformity.

PURPOSE: To investigate kinematic adaptations from self-selected to fast speed walking in ASD patients. METHODS: 115 primary ASD and 66 controls underwent biplanar radiographic X-rays and 3D gait analysis to calculate trunk, segmental spine and lower limb kinematics during self-selected and fast speed walking. Kinematic adaptation was calculated as the difference (Δ) between fast and self-selected speed walking. ASD with 7 or more limited kinematic adaptation parameters were classified as ASD-limited-KA, while those with less than 7 limited kinematic adaptation parameters were classified as ASD-mild-KA. RESULTS: 25 patients were classified as ASD-limited-KA and 90 as ASD-mild-KA. ASD-limited-KA patients walked with a lesser increase of pelvic rotation (Δ = 1.7 vs 5.5°), sagittal hip movement (Δ = 3.1 vs 7.4°) and shoulder-pelvis axial rotation (Δ = 3.4 vs 6.4°) compared to controls (all p < 0.05). ASD-limited-KA had an increased SVA (60.6 vs - 5.7 mm), PT (23.7 vs 11.9°), PI-LL (9.7 vs - 11.7°), knee flexion (9.2 vs - 0.4°) and a decreased LL (44.0 vs 61.4°) compared to controls (all p < 0.05). Kinematic and radiographic alterations were less pronounced in ASD-mild-KA. The limited increase of walking speed was correlated to the deteriorated physical component summary score of SF-36 (r = 0.37). DISCUSSION: Kinematic limitations during adaptation from self-selected to fast speed walking highlight an alteration of a daily life activity in ASD patients. ASD with limited kinematic adaptations showed more severe sagittal malalignment with an increased SVA, PT, PI-LL, and knee flexion, a decreased LL and the most deteriorated quality of life. This highlights the importance of 3D movement analysis in the evaluation of ASD.

Role of bilateral staged hip arthroplasty in Hip-spine syndrome: A case report.

RATIONALE: Hip-spine syndrome is a frequent finding in patients presenting with symptoms both at the level of the hip and spine. PATIENT CONCERNS: Patient previously operated of lumbar laminectomy for supposed spinal stenosis presenting with persistent pain and disability. DIAGNOSES: Clinical examination and imaging showed severe bilateral hip osteoarthritis. Full body standing and sitting biplanar radiographs showed an associated severe sagittal malalignment. 3D motion analysis and health-related quality of life (HRQOL) questionnaires showed a severe functional impact. INTERVENTIONS: He was operated of a staged bilateral total hip arthroplasty using the direct anterior approach. OUTCOMES: Spinopelvic and sagittal alignment parameters, as well as 3D motion analysis and HRQOL scores showed significant improvement after the first, then the second total hip arthroplasty. LESSONS: Comprehensive functional diagnostic testing, including full body standing and seated radiographs, 3D gait analysis and HRQOL questionnaires may provide important information for future management.

MRI quantitative muscle characterization in children with X-linked hypophosphatemia.

INTRODUCTION: Children with X Linked Hypophosphatemia (XLH) suffer from carential ricket, bone deformities and lameness. No previous study demonstrated a morphological distinction in muscles in these patients. The aim of this prospective study was to characterize, using Magnetic Resonance Imaging (MRI), the muscle morphology of pelvis, thigh and leg in children with XLH and to compare it with typically developed (TD) children. HYPOTHESIS: We hypothesized that lower limbs muscles in children with XLH are different from TD children and could explain limp walking. MATERIAL AND METHODS: Three-dimensional reconstructions of the muscles were performed in 11 patients with XLH and 15 TD children. Muscle lengths, sections and volumes were calculated and normalized with height and weight. Mean age was 10. RESULTS: Lengths were all smaller in children with XLH except for the Medius/minimus gluteus muscles (p=0.64). The difference seemed higher in muscles with a long tendinous part as semitendinosus (0.139 vs 0,164; p<0.01). All volumes were significantly inferior in children with XLH. This preliminary study showed significant differences in muscle structures between patients with XLH and TD children. DISCUSSION: Medius/minimus gluteus seemed to be particularly developed in children with XLH. Nevertheless it is not possible to conclude if it is related to XLH or a consequence of bone deformities. LEVEL OF PROOF: IV.

Risk Factors for Failure of Calcaneal Lengthening Osteotomy in Children and Adolescents With Planovalgus Foot Deformity: A Retrospective Study.

INTRODUCTION: The calcaneal lengthening procedure (CLP) is a well-known surgical technique used for the correction of symptomatic planovalgus foot deformities. Literature shows a significant rate of relapse and undercorrection of the foot post-operatively. Factors determining the failure or success of CLP are still not well understood. The purpose of this retrospective study was to assess the most significant factors related to the failure of this procedure. METHODS: A case-control retrospective study was conducted on 50 patients (80 feet) aged 12.4±2.5 years who underwent CLP. A clinical (demographic parameters, etiology, Gross Motor Function Classification System (GMFCS) level) and radiological evaluation were assessed preoperatively and repeated postoperatively at 56.5±32.5 months. Two methods of osteotomy bone fixation were studied: K-wires vs. eight-plate. Standing anteroposterior (AP) and lateral (L) radiographs were done, and the following radiographic parameters were measured: calcaneocuboid (CC) joint subluxation classified into normal, moderate, and severe (L); AP and L talo-first metatarsal (T1MT) angle; AP talonavicular (TN) coverage angle; AP and L talocalcaneal (TC) angle; calcaneal pitch (CP) angle; and L talo-horizontal (TH) angle. Mosca's criteria were used for clinical and radiological assessments. The association between demographic data, clinical and radiological results, and the variation between preoperative and postoperative angles were studied. The main risk factors affecting clinical results and CC joint subluxation were investigated (logistic regression and analysis of covariance (ANCOVA)). RESULTS: Satisfactory clinical results were associated with satisfactory radiological ones on Mosca's criteria (p<0.001). The use of an eight-plate for osteotomy fixation gave better results than K-wires (79% vs. 59%). Radiological angles were improved in both techniques postoperatively (increase of CP and L-TC and decrease of AP-T1MT, AP-TC, AP-TN, and L-T1MT, all p<0.05). Non-satisfactory clinical results were associated with a high GMFCS level, a low preoperative AP-TN coverage angle, and a low preoperative CP angle (R2=0.45). Both a young age and a low CP angle preoperatively were associated with CC subluxation (R2=0.31). CONCLUSION: The neurological status and the severity of the planovalgus foot deformity preoperatively were the main risk factors affecting clinical outcomes after CLP. However, young age and the severity of the deformity preoperatively were the main risk factors behind CC joint subluxation affecting CLP outcomes.

Differences in Kinematic Changes From Self-Selected to Fast Speed Gait in Asymptomatic Adults With Radiological Signs of Femoro-Acetabular Impingement.

Femoro-acetabular impingement (FAI) may present as alterations in the skeletal morphology of the hip. Repercussions of FAI can be witnessed in self-selected speed walking as well as physical exercise such as running or fast speed walking. The aim of this study was to investigate changes in kinematics at different gait speeds in subjects presenting with radiological findings invoking FAI. One hundred thirty asymptomatic adults underwent biplanar X-rays with a calculation of 3D hip parameters: acetabular anteversion, abduction and tilt, vertical center edge angle (VCE), femoral anteversion, neck-shaft angle, acetabular coverage of the femoral head, femoral head diameter and neck length. Parameters were classified according to FAI clinical thresholds. Two groups were created: Control group (63 subjects having up to one subnormal hip parameter in favour of FAI) and Radiographic FAI group (67 subjects having ≥2 subnormal hip parameters that might cause FAI). All subjects underwent 3D gait analysis at self-selected and fast speed, from which kinematic parameters were generated. Arithmetic differences between fast and self-selected speed gait were considered as gait changes. Subjects in the Radiographic FAI group had decreased acetabular tilt (24 vs. 19˚), anteversion (19 vs. 16˚), abduction (55 vs. 53˚), femoral anteversion (18 vs. 14˚) and increased VCE (29 vs. 33˚, all p<0.05), compared to controls. Changes from self-selected to fast speed showed that subjects in the Radiographic FAI group had lower range of motion (ROM) pelvic rotation (7 vs. 4˚) and ROM hip flexion/extension (10 vs. 7˚), reduced hip extension (-4 vs. -2˚) and step length (16 vs. 13 cm; all p<0.05). The Radiographic FAI group had decreased acetabular abduction, anteversion and femoral anteversion in favour of FAI. When adapting from self-selected to fast speed gait, the Radiographic FAI group seemed to limit pelvic rotation and hip flexion/extension resulting in a decrease in step length. These kinematic limitations were previously reported in subjects with symptomatic FAI. Gait analysis could be considered as a functional diagnostic tool to assess FAI along with radiological assessment.

ASD with high pelvic retroversion develop changes in their acetabular orientation during walking.

Introduction: It was hypothesized that pelvic retroversion in Adult Spinal Deformity (ASD) can be related to an increased hip loading explaining the occurrence of hip-spine syndrome. Research question: How pelvic retroversion can modify acetabular orientation in ASD during walking? Methods: 89 primary ASD and 37 controls underwent 3D gait analysis and full-body biplanar X-rays. Classic spinopelvic parameters were calculated from 3D skeletal reconstructions in addition to acetabular anteversion, abduction, tilt, and coverage. Then, 3D bones were registered on each gait frame to compute the dynamic value of the radiographic parameters during walking. ASD patients having a high PT were grouped as ASD-highPT, otherwise as ASD-normPT. Control group was divided in: C-aged and C-young, age matched to ASD-hightPT and ASD-normPT respectively. Results: 25/89 patients were classified as ASD-highPT having a radiographic PT of 31° (vs 12° in other groups, p â€‹< â€‹0.001). On static radiograph, ASD-highPT showed more severe postural malalignment than the other groups: ODHA â€‹= â€‹5°, L1L5 â€‹= â€‹17°, SVA â€‹= â€‹57.4 â€‹mm (vs 2°, 48° and 5 â€‹mm resp. in other groups,all p â€‹< â€‹0.001). During gait, ASD-highPT presented a higher dynamic pelvic retroversion of 30° (vs 15° in C-aged), along with a higher acetabular anteversion of 24° (vs 20°), external coverage of 38° (vs 29°) and a lower anterior coverage of 52° (vs 58°,all p â€‹< â€‹0.05). Conclusion: ASD patients with severe pelvic retroversion showed an increased acetabular anteversion, external coverage and lower anterior coverage during gait. These changes in acetabular orientation, computed during walking, were shown to be related to hip osteoarthritis.

Functional assessment using 3D movement analysis can better predict health-related quality of life outcomes in patients with adult spinal deformity: a machine learning approach.

Introduction: Adult spinal deformity (ASD) is classically evaluated by health-related quality of life (HRQoL) questionnaires and static radiographic spino-pelvic and global alignment parameters. Recently, 3D movement analysis (3DMA) was used for functional assessment of ASD to objectively quantify patient's independence during daily life activities. The aim of this study was to determine the role of both static and functional assessments in the prediction of HRQoL outcomes using machine learning methods. Methods: ASD patients and controls underwent full-body biplanar low-dose x-rays with 3D reconstruction of skeletal segment as well as 3DMA of gait and filled HRQoL questionnaires: SF-36 physical and mental components (PCS&MCS), Oswestry Disability Index (ODI), Beck's Depression Inventory (BDI), and visual analog scale (VAS) for pain. A random forest machine learning (ML) model was used to predict HRQoL outcomes based on three simulations: (1) radiographic, (2) kinematic, (3) both radiographic and kinematic parameters. Accuracy of prediction and RMSE of the model were evaluated using 10-fold cross validation in each simulation and compared between simulations. The model was also used to investigate the possibility of predicting HRQoL outcomes in ASD after treatment. Results: In total, 173 primary ASD and 57 controls were enrolled; 30 ASD were followed-up after surgical or medical treatment. The first ML simulation had a median accuracy of 83.4%. The second simulation had a median accuracy of 84.7%. The third simulation had a median accuracy of 87%. Simulations 2 and 3 had comparable accuracies of prediction for all HRQoL outcomes and higher predictions compared to Simulation 1 (i.e., accuracy for PCS = 85 ± 5 vs. 88.4 ± 4 and 89.7% ± 4%, for MCS = 83.7 ± 8.3 vs. 86.3 ± 5.6 and 87.7% ± 6.8% for simulations 1, 2 and 3 resp., p < 0.05). Similar results were reported when the 3 simulations were tested on ASD after treatment. Discussion: This study showed that kinematic parameters can better predict HRQoL outcomes than stand-alone classical radiographic parameters, not only for physical but also for mental scores. Moreover, 3DMA was shown to be a good predictive of HRQoL outcomes for ASD follow-up after medical or surgical treatment. Thus, the assessment of ASD patients should no longer rely on radiographs alone but on movement analysis as well.

Spinopelvic Adaptations in Standing and Sitting Positions in Patients With Adult Spinal Deformity.

Purpose To describe spinopelvic adaptations in the standing and sitting positions in patients with adult spinal deformity (ASD). Methods Ninety-five patients with ASD and 32 controls completed health-related quality of life (HRQOL) questionnaires: short form 36 (SF36), Oswestry Disability Index (ODI), and visual analog scale (VAS) for pain. They underwent biplanar radiography in both standing and sitting positions. Patients with ASD were divided into ASD-front (frontal deformity Cobb > 20°, n = 24), ASD-sag (sagittal vertical axis (SVA) > 50 mm, pelvic tilt (PT) > 25°, or pelvic incidence (PI)-lumbar lordosis (LL) > 10°, n = 40), and ASD-hyper thoracic kyphosis (TK >60°, n = 31) groups. Flexibility was defined as the difference (Δ) in radiographic parameters between the standing and sitting positions. The radiographic parameters were compared between the groups. Correlations between HRQOL scores were evaluated. Results All participants increased their SVA from standing to sitting (ΔSVA<0), except for patients with ASD-sag, who tended to decrease their SVA (78-62 mm) and maximize their pelvic retroversion (27-40° vs 10-34° in controls, p<0.001). They also showed reduced thoracic and lumbar flexibility (ΔLL = 3.4 vs 37.1°; ΔTK = -1.7 vs 9.4° in controls, p<0.001). ASD-hyperTK showed a decreased PT while sitting (28.9 vs 34.4° in controls, p<0.001); they tended to decrease their LL and TK but could not reach values for controls (ΔLL = 22.8 vs 37.1° and ΔTK = 5.2 vs 9.4°, p<0.001). The ASD-front had normal standing and sitting postures. ΔSVA and ΔLL were negatively correlated with the physical component scale (PCS of SF36) and ODI (r = -0.39 and r = -0.46, respectively). Conclusion Patients with ASD present with different spinopelvic postures and adaptations from standing to sitting positions, with those having sagittal malalignment most affected. In addition, changes in standing and sitting postures were related to HRQOL outcomes. Therefore, surgeons should consider patient sitting adaptations in surgical planning and spinal fusion. Future studies on ASD should evaluate whether physical therapy or spinal surgery can improve sitting posture and QOL, especially for those with high SVA or PT.

Alterations of gait kinematics depend on the deformity type in the setting of adult spinal deformity.

PURPOSE: To evaluate 3D kinematic alterations during gait in Adult Spinal Deformity (ASD) subjects with different deformity presentations. METHODS: One hundred nineteen primary ASD (51 ± 19y, 90F), age and sex-matched to 60 controls, underwent 3D gait analysis with subsequent calculation of 3D lower limb, trunk and segmental spine kinematics as well as the gait deviation index (GDI). ASD were classified into three groups: 51 with sagittal malalignment (ASD-Sag: SVA > 50 mm, PT > 25°, and/or PI-LL > 10°), 28 with only frontal deformity (ASD-Front: Cobb > 20°) and 40 with only hyperkyphosis (ASD-HyperTK: TK > 60°). Kinematics were compared between groups. RESULTS: ASD-Sag had a decreased pelvic mobility compared to controls with a decreased ROM of hips (38 vs. 45°) and knees (51 vs. 61°). Furthermore, ASD-Sag exhibited a decreased walking speed (0.8 vs. 1.2 m/s) and GDI (80 vs. 95, all p < 0.05) making them more prone to falls. ASD-HyperTK showed similar patterns but in a less pronounced way. ASD-Front had normal walking patterns. GDI, knee flex/extension and walking speed were significantly associated with SVA and PT (r = 0.30-0.65). CONCLUSION: Sagittal spinal malalignment seems to be the driver of gait alterations in ASD. Patients with higher GT, SVA, PT or PI-LL tended to walk slower, with shorter steps in order to maintain stability with a limited flexibility in the pelvis, hips and knees. These changes were found to a lesser extent in ASD with only hyperkyphosis but not in those with only frontal deformity. 3D gait analysis is an objective tool to evaluate functionality in ASD patients depending on their type of spinal deformity. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Assessment of dynamic balance during walking in patients with adult spinal deformity.

PURPOSE: To assess dynamic postural alignment in ASD during walking using a subject-specific 3D approach. METHODS: 69 ASD (51 ± 20 years, 77%F) and 62 controls (34 ± 13 years, 62%F) underwent gait analysis along with full-body biplanar Xrays and filled HRQoL questionnaires. Spinopelvic and postural parameters were computed from 3D skeletal reconstructions, including radiographic odontoid to hip axis angle (ODHA) that evaluates the head's position over the pelvis (rODHA), in addition to rSVA and rPT. The 3D bones were then registered on each gait frame to compute the dynamic ODHA (dODHA), dSVA, and dPT. Patients with high dODHA (> mean + 1SD in controls) were classified as ASD-DU (dynamically unbalanced), otherwise as ASD-DB (dynamically balanced). Between-group comparisons and relationship between parameters were investigated. RESULTS: 26 patients were classified as ASD-DU having an average dODHA of 10.4° (ASD-DB: 1.2°, controls: 1.7°), dSVA of 112 mm (ASD-DB: 57 mm, controls: 43 mm), and dPT of 21° (ASD-DB: 18°, controls: 14°; all p < 0.001). On static radiographs, ASD-DU group showed more severe sagittal malalignment than ASD-DB, with more altered HRQoL outcomes. The ASD-DU group had an overall abnormal walking compared to ASD-DB & controls (gait deviation index: 81 versus 93 & 97 resp., p < 0.001) showing a reduced flexion/extension range of motion at the hips and knees with a slower gait speed and shorter step length. Dynamic ODHA was correlated to HRQoL scores. CONCLUSION: Dynamically unbalanced ASD had postural malalignment that persist during walking, associated with kinematic alterations in the trunk, pelvis, and lower limbs, making them more prone to falls. Dynamic-ODHA correlates better with HRQoL outcomes than dSVA and dPT.

Gait kinematic alterations in subjects with adult spinal deformity and their radiological determinants.

BACKGROUND: Adults with spinal deformity (ASD) are known to have postural malalignment affecting their quality of life. Classical evaluation and follow-up are usually based on full-body static radiographs and health related quality of life questionnaires. Despite being an essential daily life activity, formal gait assessment lacks in clinical practice. RESEARCH QUESTION: What are the main alterations in gait kinematics of ASD and their radiological determinants? METHODS: 52 ASD and 63 control subjects underwent full-body 3D gait analysis with calculation of joint kinematics and full-body biplanar X-rays with calculation of 3D postural parameters. Kinematics and postural parameters were compared between groups. Determinants of gait alterations among postural radiographic parameters were explored. RESULTS: ASD had increased sagittal vertical axis (SVA:34 ±â€¯59 vs -5 ±â€¯20 mm), pelvic tilt (PT:19 ±â€¯13 vs 11 ±â€¯6°) and frontal Cobb (25 ±â€¯21 vs 4 ±â€¯6°) compared to controls (all p < 0.001). ASD displayed decrease walking speed (0.9 ±â€¯0.3 vs 1.2 ±â€¯0.2 m/s), step length (0.58 ±â€¯0.11 vs 0.64 ±â€¯0.07 m) and increased single support (0.45 ±â€¯0.05 vs 0.42 ±â€¯0.04 s). ASD walked with decreased hip extension in stance (-3 ±â€¯10 vs -7 ±â€¯8°), increased knee flexion at initial contact and in stance (10 ±â€¯11 vs 5 ±â€¯10° and 19 ±â€¯7 vs 16 ±â€¯8° respectively), and decreased knee flexion/extension ROM (55 ±â€¯9 vs 59 ±â€¯7°). ASD had increased trunk flexion (12 ±â€¯12 vs 6 ±â€¯11°) and reduced dynamic lumbar lordosis (-11 ±â€¯12 vs -15 ±â€¯7°, all p < 0.001). Sagittal knee ROM, walking speed and step length were negatively determined by SVA; lack of lumbar lordosis during gait was negatively determined by radiological lumbar lordosis. SIGNIFICANCE: Static compensations in ASD persist during gait, where they exhibit a flexed attitude at the trunk, hips and knees, reduced hip and knee mobility and loss of dynamic lordosis. ASD walked at a slower pace with increased single and double support times that might contribute to their gait stability. These dynamic discrepancies were strongly related to static sagittal malalignment.

Alteration of the Sitting and Standing Movement in Adult Spinal Deformity.

Adults with spinal deformity (ASD) are known to have spinal malalignment affecting their quality of life and daily life activities. While walking kinematics were shown to be altered in ASD, other functional activities are yet to be evaluated such as sitting and standing, which are essential for patients' autonomy and quality of life perception. In this cross-sectional study, 93 ASD subjects (50 ± 20 years; 71 F) age and sex matched to 31 controls (45 ± 15 years; 18 F) underwent biplanar radiographic imaging with subsequent calculation of standing radiographic spinopelvic parameters. All subjects filled HRQOL questionnaires such as SF36 and ODI. ASD were further divided into 34 ASD-sag (with PT > 25° and/or SVA >5 cm and/or PI-LL >10°), 32 ASD-hyperTK (with only TK >60°), and 27 ASD-front (with only frontal malalignment: Cobb >20°). All subjects underwent 3D motion analysis during the sit-to-stand and stand-to-sit movements. The range of motion (ROM) and mean values of pelvis, lower limbs, thorax, head, and spinal segments were calculated on the kinematic waveforms. Kinematics were compared between groups and correlations to radiographic and HRQOL scores were computed. During sit-to-stand and stand-to-sit movements, ASD-sag had decreased pelvic anteversion (12.2 vs 15.2°), hip flexion (53.0 vs 62.2°), sagittal mobility in knees (87.1 vs 93.9°), and lumbar mobility (L1L3-L3L5: -9.1 vs -6.8°, all p < 0.05) compared with controls. ASD-hyperTK showed increased dynamic lordosis (L1L3-L3L5: -9.1 vs -6.8°), segmental thoracic kyphosis (T2T10-T10L1: 32.0 vs 17.2°, C7T2-T2T10: 30.4 vs 17.7°), and thoracolumbar extension (T10L1-L1L3: -12.4 vs -5.5°, all p < 0.05) compared with controls. They also had increased mobility at the thoracolumbar and upper-thoracic spine. Both ASD-sag and ASD-hyperTK maintained a flexed trunk, an extended head along with an increased trunk and head sagittal ROM. Kinematic alterations were correlated to radiographic parameters and HRQOL scores. Even after controlling for demographic factors, dynamic trunk flexion was determined by TK and PI-LL mismatch (adj. R 2 = 0.44). Lumbar sagittal ROM was determined by PI-LL mismatch (adj. R 2 = 0.13). In conclusion, the type of spinal deformity in ASD seems to determine the strategy used for sitting and standing. Future studies should evaluate whether surgical correction of the deformity could restore sitting and standing kinematics and ultimately improve quality of life.

How do skeletal and postural parameters contribute to maintain balance during walking?

INTRODUCTION: Maintaining balance during gait allows subjects to minimize energy expenditure and avoid falls. Gait balance can be measured by assessing the relationship between the center of mass (COM) and center of pressure (COP) during gait. Demographics, skeletal and postural parameters are known to influence gait balance. PURPOSE: What are the determinants of dynamic balance during gait in asymptomatic adults among skeletal and demographic parameters? METHODS: 115 adults underwent 3D gait analysis and full-body biplanar X-rays. Angles between the COM-COP line and the vertical were calculated in frontal and sagittal planes during gait: maxima, minima, and ROM were evaluated. Full-body 3D reconstructions were obtained; skeletal and postural parameters of the spine (lumbar lordosis, thoracic kyphosis, sagittal vertical axis SVA), pelvis (pelvic tilt and incidence, acetabular orientation in the 3 planes) and lower limbs (neck shaft angle femoral and tibial torsions) were calculated. A univariate followed by a multivariate analysis were computed between the COM-COP parameters and skeletal and demographic parameters. RESULTS: The univariate analysis showed that in the frontal plane, maximum (4.6°) of the COM-COP angle was significantly correlated with weight (r = 0.53), age (r = 0.28), height (r = 0.35), SVA (r = 0.23), T1T12 (r = 0.24) and pelvic width (r = 0.25).In the sagittal plane, maximum COM-COP (19.7 ± 2.8°) angle was significantly correlated to acetabular tilt (r = 0.25) and acetabular anteversion (r = 0.21). The multivariate analysis showed that, in the frontal plane, an increase in the maximum of the COM-COP angle was determined by a decreasing height (ß = -0.28), an increasing weight (ß = 0.48), being a male (ß = -0.42), and an increasing posterior acetabular coverage (ß = 0.22). In the sagittal plane, an increasing maximum COM-COP angle was determined by a decreasing height (ß = -0.38) and an increasing SVA (ß = 0.19). CONCLUSION: Frontal imbalance appeared to be mainly correlated to demographic parameters. Sagittal imbalance was found to be correlated with weight, height, acetabular parameters and SVA. These results suggest that in addition to demographic parameters, acetabular parameters and SVA are important determinants of balance during gait.

Influence of spino-pelvic and postural alignment parameters on gait kinematics.

INTRODUCTION: Postural alignment is altered with spine deformities that might occur with age. Alteration of spino-pelvic and postural alignment parameters are known to affect daily life activities such as gait. It is still unknown how spino-pelvic and postural alignment parameters are related to gait kinematics. RESEARCH QUESTION: To assess the relationships between spino-pelvic/postural alignment parameters and gait kinematics in asymptomatic adults. METHODS: 134 asymptomatic subjects (aged 18-59 years) underwent 3D gait analysis, from which kinematics of the pelvis and lower limbs were extracted in the 3 planes. Subjects then underwent full-body biplanar X-rays, from which skeletal 3D reconstructions and spino-pelvic and postural alignment parameters were obtained such as sagittal vertical axis (SVA), center of auditory meatus to hip axis plumbline (CAM-HA), thoracic kyphosis (TK) and radiologic pelvic tilt (rPT). In order to assess the influence of spino-pelvic and postural alignment parameters on gait kinematics a univariate followed by a multivariate analysis were performed. RESULTS: SVA was related to knee flexion during loading response (ß = 0.268); CAM-HA to ROM pelvic obliquity (ß = -0.19); rPT to mean pelvic tilt (ß = -0.185) and ROM pelvic obliquity (ß = -0.297); TK to ROM hip flexion/extension in stance (ß = -0.17), mean foot progression in stance (ß = -0.329), walking speed (ß = -0.19), foot off (ß = 0.223) and step length (ß = -0.181). SIGNIFICANCE: This study showed that increasing SVA, CAM-HA, TK and rPT, which is known to occur in adults with spinal deformities, could alter gait kinematics. Increases in these parameters, even in asymptomatic subjects, were related to a retroverted pelvis during gait, a reduced pelvic obliquity and hip flexion/extension mobility, an increased knee flexion during loading response as well as an increase in external foot progression angle. This was associated with a decrease in the walking pace: reduced speed, step length and longer stance phase.

Is the apical vertebra the most rotated vertebra in the scoliotic curve?

OBJECTIVE: The aim of this study was to determine if the apical vertebra (AV) in patients with adolescent idiopathic scoliosis (AIS) is the most rotated vertebra in the scoliotic segment. METHODS: A total of 158 patients with AIS (Cobb angle range 20°-101°) underwent biplanar radiography with 3D reconstructions of the spine and calculation of vertebral axial rotations. The type of major curvature was recorded (thoracic, thoracolumbar, or lumbar), and both major and minor curvatures were included. The difference of levels (DL) between the level of maximal vertebral rotation (LMVR) and the AV was calculated as follows: DL = 0 if LMVR and AV were the same, DL = 1 if LMVR was directly above or below the AV, and DL = 2 if LMVR was separated by 1 vertebra or more from the AV. To investigate which factors explained the divergence of the LMVR from the AV, multinomial models were computed. RESULTS: The distribution of the DL was as follows: for major curvatures, 143 were DL = 0, 11 were DL = 1, and 4 were DL = 2; and for minor curvatures, 53 were DL = 0, 9 were DL = 1, and 31 were DL = 2. The determinants of a DL = 2 (compared with DL = 0) were lumbar curvature (compared with thoracic; adjusted OR 0.094, p = 0.001), major curvature (compared with minor; adjusted OR 0.116, p = 0.001), and curvatures with increasing apical vertebral rotation (adjusted OR 0.788, p < 0.001). CONCLUSIONS: This study showed that the AV is the most rotated vertebra in the majority of major curvatures, while in minor curvatures, the most rotated vertebra appears to be the junctional vertebra between major and minor curvatures in a significant proportion of cases.

Alterations of treatment-naïve pelvis and thigh muscle morphology in children with cerebral palsy.

Lower limb (LL) muscle morphology and growth are altered in children with cerebral palsy (CP). Muscle alterations differ with age and with severity of motor impairment, classified according to the gross motor classification system (GMFCS). Muscle alterations differ also with orthopedic intervention, frequently performed at the level of the shank muscles since an early age, such as the gastrocnemius. The aim was to investigate the alterations of treatment-naïve pelvis and thigh muscle lengths and volumes in children with GMFCS levels I and II, of varying ages. 17 children with CP (GMFCS I: N = 9, II: N = 8, age: 11.7 ±â€¯4 years), age-matched to 17 typically developing (TD) children, underwent MRI of the LL. Three-dimensional reconstructions of the muscles were performed bilaterally. Muscle volumes and lengths were calculated in 3D and compared between groups. Linear regression between muscle volumes and age were computed. Adductor-brevis and gracilis lengths, as well as rectus-femoris volume, were decreased in GMFCS I compared to TD (p < 0.05). Almost all the reconstructed muscle volumes and lengths were found to be altered in GMFCS II compared to TD and GMFCS I. All muscle volumes showed significant increase with age in TD and GMFCS I (R2 range: 0.3-0.9, p < 0.05). Rectus-femoris, hamstrings and adductor-longus showed reduced increase in the muscle volume with age in GMFCS II when compared to TD and GMFCS I. Alterations of treatment-naïve pelvis and thigh muscle volumes and lengths, as well as muscle growth, seem to increase with the severity of motor impairment in ambulant children with CP.

Roussouly's sagittal spino-pelvic morphotypes as determinants of gait in asymptomatic adult subjects.

Sagittal alignment is known to greatly vary between asymptomatic adult subjects; however, there are no studies on the possible effect of these differences on gait. The aim of this study is to investigate whether asymptomatic adults with different Roussouly sagittal alignment morphotypes walk differently. Ninety-one asymptomatic young adults (46M & 45W), aged 21.6±2.2years underwent 3D gait analysis and full body biplanar X-rays with three-dimensional (3D) reconstructions of their spines and pelvises and generation of sagittal alignment parameters. Subjects were divided according to Roussouly's sagittal alignment classification. Sagittal alignment and kinematic parameters were compared between Roussouly types. 17 subjects were classified as type 2, 47 as type 3, 26 as type 4 but only 1 as type 1. Type 2 subjects had significantly more mean pelvic retroversion (less mean pelvic tilt) during gait compared to type 3 and 4 subjects (type 2: 8.2°; type 3:11.2°, type 4: 11.3°) and significantly larger ROM pelvic obliquity compared to type 4 subjects (type 2: 11.0°; type 4: 9.1°). Type 2 subjects also had significantly larger maximal hip extension during stance compared to subjects of types 3 and 4 (type 2: -11.9°; type 3: -8.8°; type 4: -7.9°) and a larger ROM of ankle plantar/dorsiflexion compared to type 4 subjects (type 2: 31.1°; type 4: 27.9°). Subjects with type 2 sagittal alignment were shown to have a gait pattern involving both increased hip extension and pelvic retroversion which could predispose to posterior femoroacetabular impingement and consequently osteoarthritis.

Three-dimensional kinematics of upper limb anatomical movements in asymptomatic adults: Dominant vs. non-dominant.

The effect of dominance on upper limb (UL) kinematics has only been studied on scapular movements. Moreover, when an anatomical UL movement is performed in a specific plane, secondary movements in the remaining planes involuntarily occur. These secondary movements have not been previously evaluated. The aim of this study was to compare the kinematics of primary and secondary angles of dominant and non-dominant UL during anatomical movements in asymptomatic adults. 25 asymptomatic adults performed 6 anatomical movements bilaterally: shoulder flexion-extension, abduction-adduction, horizontal abduction-adduction, internal-external rotation, elbow flexion-extension and wrist pronation-supination. Kinematics of the dominant and non-dominant UL were compared by their ranges of motion (ROM) and their angular waveforms (Coefficient of Multiple Correlations, CMC). The comparison between dominant and non-dominant UL kinematics showed different strategies of movement, most notably during elbow flexion-extension (CMC=0.29): the dominant UL exhibited more pronation at maximal elbow flexion. Significant secondary angles were found on most of the UL anatomical movements; e.g. a secondary ROM of shoulder (humero-thoracic) external-internal rotation (69°±16°) was found when the subject intended to perform maximal shoulder abduction-adduction (119°±21°). Bias of dominance should be considered when comparing pathological limb to the controlateral one. Normative values of primary and secondary angles during anatomical movements could be used as a reference for future studies on UL of subjects with neurological or orthopedic pathologies.

Validation of hip joint center localization methods during gait analysis using 3D EOS imaging in typically developing and cerebral palsy children.

Localization of the hip joint center (HJC) is essential in computation of gait data. EOS low dose biplanar X-rays have been shown to be a good reference in evaluating various methods of HJC localization in adults. The aim is to evaluate predictive and functional techniques for HJC localization in typically developing (TD) and cerebral palsy (CP) children, using EOS as an image based reference. Eleven TD and 17 CP children underwent 3D gait analysis. Six HJC localization methods were evaluated in each group bilaterally: 3 predictive (Plug in Gait, Bell and Harrington) and 3 functional methods based on the star arc technique (symmetrical center of rotation estimate, center transformation technique and geometrical sphere fitting). All children then underwent EOS low dose biplanar radiographs. Pelvis, lower limbs and their corresponding external markers were reconstructed in 3D. The center of the femoral head was considered as the reference (HJCEOS). Euclidean distances between HJCs estimated by each of the 6 methods and the HJCEOS were calculated; distances were shown to be lower in predictive compared to functional methods (p<0.0001). Contrarily to findings in adults, functional methods were shown to be less accurate than predictive methods in TD and CP children, which could be mainly due to the shorter thigh segment in children. Harrington method was shown to be the most accurate in the prediction of HJC (mean error≈18mm, SD=9mm) and quasi-equivalent to the Bell method. The bias for each method was quantified, allowing its correction for an improved HJC estimation.