SAM

Quasi-automatic early detection of progressive idiopathic scoliosis from biplanar radiography: a preliminary validation

COURTOIS, Isabelle — Tue, 01 Jan 2019 00:00:00 GMT

Quasi-automatic early detection of progressive idiopathic scoliosis from biplanar radiography: a preliminary validation COURTOIS, Isabelle; EBERMEYER, Eric; ABELIN-GENEVOIS, Kariman; KIM, Youngwoo; LANGLAIS, Tristan; VIALLE, Raphaël; ASSI, Ayman; GHANEM, Ismat; DUBOUSSET, Jean; SKALLI, Wafa; GAJNY, Laurent; VERGARI, Claudio Purpose To validate the predictive power and reliability of a novel quasi-automatic method to calculate the severity index of adolescent idiopathic scoliosis (AIS). Methods Fifty-five AIS patients were prospectively included (Age: 10-15, Cobb: 16° ± 4°). Patients underwent low-dose biplanar x-rays and a novel fast method for 3D reconstruction of the spine was performed. They were followed until skeletal maturity (stable patients) or brace prescription (progressive patients). The severity index was calculated at the first exam, based on 3D parameters of the scoliotic curve, and it was compared with the patient’s final outcome (progressive or stable). Three operators have repeated the 3D reconstruction twice for a subset of 30 patients to assess reproducibility (through Cohen’s kappa and intraclass correlation coefficient). Results 85% of the patients were correctly classified as stable or progressive by the severity index, with a sensitivity of 92% and specificity of 74%. Substantial intra-operator agreement and good inter-operator agreement were observed, with 80% of the progressive patients correctly detected at the first exam. The novel severity index assessment took less than 4 minutes of operator time. Conclusions The fast and semi-automatic method for 3D reconstruction developed in this work allowed for a fast and reliable calculation of the severity index. The method is fast and user friendly. Once extensively validated, this severity index could allow very early initiation of conservative treatment for progressive patients, thus increasing treatment efficacy and therefore reducing the need for corrective surgery.

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

ASSI, Ayman — Fri, 01 Jan 2016 00:00:00 GMT

Validation of hip joint center localization methods during gait analysis using 3D EOS imaging in typically developing and cerebral palsy children ASSI, Ayman; SAURET, Christophe; MASSAAD, Abir; BAKOUNY, Ziad; SKALLI, Wafa; GHANEM, Ismat; PILLET, Helene 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 ≈ 18 mm, SD = 9 mm) and quasi-equivalent to the Bell method. The bias for each method was quantified, allowing its correction for an improved HJC estimation.

Influence of patient rotational malpositioning on pelvic parameters assessed on lateral radiographs

ASSI, Ayman — Sun, 01 Jan 2017 00:00:00 GMT

Influence of patient rotational malpositioning on pelvic parameters assessed on lateral radiographs ASSI, Ayman; SAURET, Christophe; BAKOUNY, Ziad; SAGHBINI, Elie; KHALIL, Nour; CHELALA, Lydia; NAOUM, Elias; YARED, Fares; SKALLI, Wafa; GHANEM, Ismat Aim: To estimate the effect of patients' axial rotation (AR) during pelvic radiograph acquisition, on the reliability and validity of sagittal pelvic parameters. Materials and methods: Lateral digitally reconstructed radiographs (LDRRs) were obtained from the pelvic computed tomography (CT) scans of eight children and nine adults. Then, the AR of the pelvis was simulated and the corresponding LDRRs were reconstructed at 5°, 10°, 15°, and 20° of the AR. Pelvic parameters were measured digitally on each radiograph. Intra- and interobserver variability were evaluated at each AR position (three operators repeated the measurements three times each). The bias on each clinical parameter, in each AR position, was calculated relatively to the 0° position. Results: Interobserver variability increased similarly in children and adults with AR. It reached 4.4° for pelvic incidence and 4.7° for the sacral slope at 20° of AR. Biases on radiological parameters increased with AR and exceeded the acceptable threshold of errors when AR reached 10°. A linear regression was established (R2=0.834, p<0.0001) in order to estimate the AR of a patient on a lateral pelvic radiograph based on the measurement of the bifemoral distance normalized to the sagittal pelvic thickness. Conclusions: AR of patients during radiograph acquisition can be estimated in clinical practice, which would allow physicians to discard any radiographs where the calculated AR exceeded 10°.

Three-dimensional evaluation of skeletal deformities of the pelvis and lower limbs in ambulant children with cerebral palsy

MASSAAD, Abir — Fri, 01 Jan 2016 00:00:00 GMT

Three-dimensional evaluation of skeletal deformities of the pelvis and lower limbs in ambulant children with cerebral palsy MASSAAD, Abir; ASSI, Ayman; BAKOUNY, Ziad; SAURET, Christophe; KHALIL, Nour; SKALLI, Wafa; GHANEM, Ismat Skeletal abnormalities, affecting posture and walking pattern, increase with motor impairment in children with cerebral palsy (CP). However, it is not known whether these skeletal malalignments occur in children with slight motor impairment. Our aim was to evaluate skeletal malalignment at the level of the pelvis and lower limbs in ambulant children with CP, with slight motor impairment, using a low dose biplanar X-ray technique. Twenty-seven children with spastic CP (mean age: 10.9 ± 4 years, 7 Hemiplegia, 20 Diplegia, GMFCS levels I:17, II:10), with no previous treatments at the hips and knees, underwent EOS® biplanar X-rays. A control group consisting of 22 typically developing children was also included. Three-dimensional reconstructions of the pelvis and lower limbs were performed in order to calculate 11 radiological parameters related to the pelvis, acetabulum and lower limbs. Pelvic incidence and sacral slope were significantly increased in children with CP compared to TD children (48° ± 7° vs. 43° ± 8°, 42° ± 7° vs. 38° ± 5°, respectively, p = 0.003). Acetabular parameters did not significantly differ between the two groups. Femoral anteversion and neck shaft angle were significantly increased in children with CP (25° ± 12° vs. 14° ± 7°, p < 0.001; 134° ± 5° vs. 131° ± 5°, p = 0.005 respectively). No difference was found for tibial torsion. This study showed that even slightly impaired children with CP have an anteverted and abducted femur and present positional and morphological changes of the pelvis in the sagittal plane. The orientation of the acetabulum in 3D seems to not be affected when children with CP present slight motor impairment.

Influence of patient axial malpositioning on the trueness and precision of pelvic parameters obtained from 3D reconstructions based on biplanar radiographs

GHOSTINE, Bachir — Fri, 01 Jan 2016 00:00:00 GMT

Influence of patient axial malpositioning on the trueness and precision of pelvic parameters obtained from 3D reconstructions based on biplanar radiographs GHOSTINE, Bachir; SAURET, Christophe; ASSI, Ayman; BAKOUNY, Ziad; KHALIL, Nour; SKALLI, Wafa; GHANEM, Ismat Objectives: Radiographs are often performed to assess pelvic and hip parameters, but results depend upon correct pelvis positioning. Three-dimensional (3D) reconstruction from biplanar-radiographs should provide parameters that are less sensitive to pelvic orientation, but this remained to be evaluated. Methods: Computerized-tomographic scans of six patients were used both as a reference and for generating simulated frontal and lateral radiographs. These simulated radiographs were generated while introducing axial rotations of the pelvis ranging from 0° to 20°. Simulated biplanar-radiographs were utilized by four operators, three times each, to perform pelvic 3D-reconstructions. These reconstructions were used to assess the trueness, precision and global uncertainty of radiological pelvic and hip parameters for each position. Results: In the neutral position, global uncertainty ranged between ± 2° for pelvic tilt and ± 9° for acetabular posterior sector angle and was mainly related to precision errors (ranging from 1.5° to 7°). With increasing axial rotation, global uncertainty increased and ranged between ± 5° for pelvic tilt and ± 11° for pelvic incidence, sacral slope and acetabular anterior sector angle, mainly due to precision errors. Conclusion: Radiological parameters obtained from 3D-reconstructions, based on biplanar-radiographs, are less sensitive to axial rotation compared to plain radiographs. However, the axial rotation should nonetheless not exceed 10°.

Variation of the sagittal vertical axis during walking and its determinants

ASSI, Ayman — Mon, 01 Jan 2018 00:00:00 GMT

Variation of the sagittal vertical axis during walking and its determinants ASSI, Ayman; BAKOUNY, Ziad; BIZDIKIAN, Aren Joe; OTAYEK, Joeffroy; YARED, Fares; LAFAGE, Virginie; KHALIL, Nour; MASSAAD, Abir; GHANEM, Ismat; SKALLI, Wafa Patients with adult spinal deformities (ASD) are known to have altered postural alignment aﬀecting their quality of life and activities of daily living, especially gait. The Sagittal Vertical Axis (SVA), a postural parameter calculated as the distance between the posterior corner of the sacrum and the C7-plumbline on full-body sagittal radiographs [1], has been shown to be highly altered in ASD. Even though this parameter is positional and could vary during gait, no studies have investigated its variation during walking even in asymptomatic subjects.

How does the variation of the 3D orientation of the acetabulum during walking influence hip kinematics?

MJAESS, Georges — Mon, 01 Jan 2018 00:00:00 GMT

How does the variation of the 3D orientation of the acetabulum during walking influence hip kinematics? MJAESS, Georges; LABAKI, Chris; KARAM, Aya; BAKOUNY, Ziad; BIZDIKIAN, Aren Joe; OTAYEK, Joeffroy; YARED, Fares; SKALLI, Wafa; GHANEM, Ismat; ASSI, Ayman Acetabular cup orientation is crucial for total hip arthroplasty (THA), and its malpositioning could lead to impingement and dislocation [1]. Acetabular cup orientation currently relies on static 3D hip parameters [2] and was shown to be related to changes in pelvic positioning [3]. While pelvic position varies during walking, it is still unknown how dynamic variation of hip orientation during gait could inﬂuence hip kinematics.

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

MASSAAD, Abir — Tue, 01 Jan 2019 00:00:00 GMT

Alterations of treatment-naïve pelvis and thigh muscle morphology in children with cerebral palsy MASSAAD, Abir; ASSI, Ayman; BAKOUNY, Ziad; BIZDIKIAN, Aren Joe; SKALLI, Wafa; GHANEM, Ismat 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 ± 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.

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

MEKHAEL, Mario — Wed, 01 Jan 2020 00:00:00 GMT

How do skeletal and postural parameters contribute to maintain balance during walking? MEKHAEL, Mario; LABAKI, Chris; BIZDIKIAN, Aren Joe; BAKOUNY, Ziad; OTAYEK, Joeffroy; YARED, Fares; MASSAAD, Abir; SKALLI, Wafa; GHANEM, Ismat; ASSI, Ayman 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 COMCOP 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 (β = −0.28), an increasing weight (β = 0.48), being a male (β = −0.42), and an increasing posterior acetabular coverage (β = 0.22). In the sagittal plane, an increasing maximum COMCOP angle was determined by a decreasing height (β = −0.38) and an increasing SVA (β = 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.

Validity and reliability of different techniques of neck–shaft angle measurement

BIZDIKIAN, Aren Joe — Mon, 01 Jan 2018 00:00:00 GMT

Validity and reliability of different techniques of neck–shaft angle measurement BIZDIKIAN, Aren Joe; ASSI, Ayman; BAKOUNY, Ziad; SAGHBINI, Elie; BAKHOS, G. E.; ESBER, S.; KHALIL, Nour; OTAYEK, Joeffroy; GHANIMEH, Joe; SAURET, Christophe; SKALLI, Wafa; GHANEM, Ismat AIM: To determine a valid and reliable neck-shaft angle (NSA) measurement method while rotating the pelvises in increments of 5° in order to simulate patient malpositioning. MATERIALS AND METHODS: CT images of 17 patients were used to produce digitally reconstructed radiographs in frontal and lateral views and three-dimensional (3D)-reconstructions of the femurs, considered to be the reference standard. Malpositioning was simulated by axially rotating the frontal radiographs from 0° to 20°. Three operators measured in two-dimensions the NSA using four different methods, three times each, at each axial rotation (AR) position. Method 1 (femoral neck axis drawn by joining the centre of the femoral head (CFH) to the median of the femoral neck base; femoral diaphysis axis drawn by joining the median of two lines passing through the medial and lateral edges of the femoral axis below the lesser trochanter) and method 2 (femoral axis taken as the median of a triangle passing through base of femoral neck and medial and lateral head-neck junction; femoral diaphysis as previous) were described for the first time; method 3 was based on a previous study; method 4 was a free-hand technique. Reliability, validity, and global uncertainty were assessed. RESULTS: Method 1 showed the best reliability and validity. The global uncertainty also showed minimal values for method 1, ranging from 7.4° to 14.3° across AR positions. CONCLUSION: Method 1, based on locating the CFH, was the most reliable and valid method and should be considered as a standardised two-dimensional NSA measurement method for clinical application.