I. Ghanem

The Congenital Dislocated Spine

Study Design. The congenital dislocated spine has been defined as the potentially most serious form of congenital kyphosis with an abrupt single‐level displacement of the spinal canal. A retrospective chart review was conducted on 19 patients with this deformity. Objectives. To delineate the clinical and radiologic characteristics of this entity, and to analyze the outcome after treatment. Summary of Background Data. An anterior failure of formation was the basic feature. Kyphosis was variable. Vertebral displacement in the frontal plane was present in seven patients, and sagittal displacement was constant. Mechanical instability was seen in 17 patients. Neurologic impairment was identified in 12 patients, and congenital paraplegia was seen in eight patients. An acute paraplegia occurred after minor trauma in one patient. Methods. Seventeen patients were treated surgically. Thirteen patients underwent complete circumferential stabilization through anterior strut grafting and posterior fusion without instrumentation, usually before age 3 years. Neurosurgical decompression was done in four patients. Results. The average follow‐up period was 8 years, 6 months. Nonunion of the posterior fusion mass was detected and successfully treated in five patients. A solid fusion seemed to be obtained in all patients at last follow‐up evaluation. The neurologic status after neurosurgical decompression remained unchanged in three patients and was improved temporarily in one patient. Conclusions. Avoidance of neurologic morbidity requires early diagnosis and stabilization. The authors recommend early anterior strut grafting and posterior fusion. Exploration of the posterior fusion mass should be done systematically.

Posterior spinal fusion in neuromuscular scoliosis using a tibial strut graft : results of a long-term follow-up

Study Design. Risks and benefits of using a tibial graft for posterior spinal fusion in neuromuscular scoliosis were evaluated in a long-term follow-up study. A consecutive series of 72 patients underwent posterior spinal fusion for neuromuscular scoliosis. Objectives. Radiologic outcome was assessed to evaluate the quality of the spinal fusion. Patients were followed serially to detect donor site complications. Mean follow-up was 17 years and 8 months (minimum: 6 years, 6 months). Summary of Background Data. Mean age of the patients at the time of surgery was 15 years. Progression of the curvature was minimal at last follow-up (mean progression at last follow-up: lumbar curve, 4.5°; thoracic curve, 5.3°). Concerning donor site complications, four patients had a leg length discrepancy of less than 2 cm at last follow-up. This complication was related to tibial overgrowth at the donor site. Methods. Solid fusion was defined in this long-term study as the absence of modification of the radiologic aspect at last follow-up in addition to the presence of a massive contiguous trabecular fusion mass. Results. The fusion appeared to be solid in all patients. No obvious pseudarthrosis could be documented. The constant successful outcome differs significantly from spinal fusion that uses bank bone. The absence of stress fracture was correlated to the low level of constraint in this essentially nonambulatory population. Conclusions. This experience indicates that the tibial graft deserves consideration in posterior spinal fusion for neuromuscular scoliosis.

Repeatability and validation of gait deviation index in children: typically developing and cerebral palsy.

The Gait Deviation Index (GDI) is a dimensionless parameter that evaluates the deviation of kinematic gait from a control database. The GDI can be used to stratify gait pathology in children with cerebral palsy (CP). In this paper the repeatability and uncertainty of the GDI were evaluated. The Correlation between the GDI and the Gross Motor Function Classification System (GMFCS) was studied for different groups of children with CP (hemiplegia, diplegia, triplegia and quadriplegia). Forty-nine, typically developing children (TD) formed our database. A retrospective study was conducted on our 3D gait data and clinical exams and 134 spastic children were included. Sixteen TD children completed the gait analysis twice to evaluate the repeatability of the GDI (test-retest evaluation). Monte Carlo simulations were applied for all groups (TD and children with CP) in order to evaluate the propagation of errors stemming from kinematics. The repeatability coefficient (2SD of test-retest differences), obtained on the GDI for the 16 TD children (32 lower limbs) was ± 10. Monte Carlo simulations showed an uncertainty ranging between 0.8 and 1.3 for TD children and all groups with CP. The Spearman Rank correlation showed a moderate correlation between the GDI and the GMFCS (r=-0.44, p<0.0001).

Three-dimensional reconstructions for asymptomatic and cerebral palsy children's lower limbs using a biplanar X-ray system: A feasibility study

The aim of this study is to explore the feasibility of 3D subject-specific skeletal reconstructions of lower limb in children using stereoradiography, and to assess uncertainty of clinical and anatomical parameters for children with cerebral palsy and for healthy children. The stereoradiography technique, using the EOS(®) system (Eos-imaging(®)), is based on the acquisition of two simultaneous digital anteroposterior and lateral X-rays, from head to feet in standing position and at low radiation dose. This technique allows subject-specific skeletal 3D reconstructions. Five children with cerebral palsy (CP) and 5 typically developing children (TD) were included in the study. Two operators performed the lower limb reconstructions twice. Tridimensional reconstructions were feasible for children over the age of 5 years. The study of reproducibility of anatomical parameters defining skeletal alignment showed uncertainties under 3° for the neck shaft angle, the femoral mechanical angle, and for the femoral and tibial torsions. The maximum degree of uncertainty was obtained for the femoral tibial rotation (4° for healthy children and 3.5° for children with CP).

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

ObjectivesRadiographs 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.MethodsComputerized-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.ResultsIn 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.ConclusionRadiological 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°.Key points• Pelvic radiological parameters could be affected by patient malpositioning.• Biplanar radiograph-based 3D reconstructions were performed at increments of axial rotation.• Trueness, precision and global uncertainty were evaluated for pelvic and hip radiological parameters.• Hip parameters were less affected by rotation compared to pelvic parameters.• Maintaining the pelvis close to the neutral position is recommended to ensure the highest possible accuracy.

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.

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

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±4years, 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.

A podoscopic and descriptive study of foot deformities in patients with Down syndrome

INTRODUCTION Subjects with Down syndrome (DS) are known to be affected by various foot deformities. Despite the fact that some of these deformities have been reported in the literature, a more comprehensive description would be of benefit. The aim of this study is to investigate the prevalence of known foot deformities in patients with DS and of other previously non-described foot anomalies in this population. HYPOTHESIS Subjects with DS have an increased prevalence of foot deformities compared to control subjects. METHODS Fifty-five subjects with DS (age: 14.6±7.4 years) had undergone podiatric clinical and podoscopic examinations to study their main foot deformities and their footprints, respectively. The results of these examinations were compared to those of an age-matched asymptomatic control group of fifty-three subjects (age: 13.4±11.2 years). RESULTS Significantly more prevalent foot deformities were found in the DS group: hallux valgus (36.4%), syndactyly between the 2nd and 3rd toes (9.1%), grade II pes planus (39.1%) and grade III pes planus (30%). Moreover, joint laxity (43.6%) was significantly more prevalent in the DS group. Furthermore, the presence of an increased space between the 1st and 2nd toes in patients with DS and its prevalence (73.6%) were described for the first time. A multivariate analysis revealed a significant relationship between the presence of joint laxity and flatfoot in only the control but not the DS group. Other foot deformities were found to be consistently more frequent in the DS population but not significantly higher than the control group. DISCUSSION Although subjects with DS had significantly greater joint laxity and BMI compared to the control group, neither of these factors was found to be related to the increased prevalence of flatfoot in DS patients. LEVEL OF EVIDENCE IV-retrospective study.

Are the sagittal cervical radiographic modifiers of the Ames-ISSG classification specific to adult cervical deformity?

OBJECTIVEThe Ames-International Spine Study Group (ISSG) classification has recently been proposed as a tool for adult cervical deformity evaluation. This classification includes three radiographic cervical sagittal modifiers that have not been evaluated in asymptomatic adults. The aim of this study was to determine whether the sagittal radiographic modifiers described in the Ames-ISSG cervical classification are encountered in asymptomatic adults without alteration of health-related quality of life (HRQOL).METHODSThe authors conducted a cross-sectional study of subjects with an age ≥ 18 years and no cervical or back-related complaints or history of orthopedic surgery. All subjects underwent full-body biplanar radiographs with the measurement of cervical, segmental, and global alignment and completed the SF-36 HRQOL questionnaire. Subjects were classified according to the sagittal radiographic modifiers (chin-brow vertical angle [CBVA], mismatch between T1 slope and cervical lordosis [TS-CL], and C2-7 sagittal vertical axis [cSVA]) of the Ames-ISSG classification for cervical deformity, which also includes a qualitative descriptor of cervical deformity, the modified Japanese Orthopaedic Association (mJOA) myelopathy score, and the Scoliosis Research Society (SRS)-Schwab classification for spinal deformity assessment. Characteristics of the subjects classified by the different modifier grades were compared.RESULTSOne hundred forty-one asymptomatic subjects (ages 18-59 years, 71 females) were enrolled in the study. Twenty-seven (19.1%) and 61 (43.3%) subjects were classified as grade 1 in terms of the TS-CL and CBVA modifiers, respectively. Ninety-eight (69.5%) and 4 (2.8%) were grade 2 for these same respective modifiers. One hundred thirty-six (96.5%) subjects had at least one modifier at grade 1 or 2. There was a significant relationship between patient age and grades of TS-CL (p < 0.001, Cramers V [CV] = 0.32) and CBVA (p = 0.04, CV = 0.22) modifiers. The HRQOL, global alignment, and segmental alignment parameters were similar among the subjects with different modifier grades (p > 0.05).CONCLUSIONSThe CBVA and TS-CL radiographic modifiers of the Ames-ISSG classification do not seem to be specific to subjects with cervical deformities and can occur in asymptomatic subjects without alteration in HRQOL.

O 057 - How do postural parameters vary during walking in asymptomatic adults? A registration technique of subject-specific 3D skeletal reconstruction during gait

Postural skeletal alignment is altered with age due to intervertebral disc and joint degeneration, consequently affecting quality of life (QoL) and activities of daily living, such as gait. Postural alignment parameters of the spine, pelvis, hips and lower limbs, measured on static standing radiographs, have been widely studied in asymptomatic subjects and subjects affected by various pathologies. However, while most of these parameters are positional and could vary during gait, there are currently no studies investigating how they are modified during walking.