RUGBY AND CERVICAL SPINE INJURY

The purpose of this presentation is to present an overview about cervical spine injuries and rugby. We focus first on global epidemiology of such injuries and on the associated injury mechanisms. Then we present the different actions developed during the last decades in order to reduce the number of injuries. In a final part, a new approach based on Finite Element Modelling is proposed to identify links between injury risks and specific anatomy

Post-trauma scoliosis after conservative treatment of thoracolumbar spinal fracture in children and adolescents: results in 48 patients.

PURPOSE: Authors examined a case series of patients younger than 18 years old who had sustained a traumatic thoracolumbar spine fracture to evaluate radiological and clinical findings of coronal spinal balance, after conservative treatment. METHODS: From 1996 to 2014, a tricentric cohort of 48 patients with an average age of 12 years was radiographically reviewed at 50 months. Cobb angle of fractured vertebra and regional Cobb angle were measured both at baseline and follow-up. Analyses were done according to initial Risser grade, number of fractures and level of injury. RESULTS: There was a total of 11 scoliosis. In group with Risser grade 3 or above, with a single vertebral fracture and lumbar fracture, final regional Cobb angle was statistically higher than initial regional Cobb angle. CONCLUSIONS: The prevalence of scoliosis in our population is higher than those of idiopathic scoliosis; Risser grade 3 or above, lumbar fracture and a single fracture seem to account for more severe coronal deformatio

A new quasi-invariant parameter characterizing the postural alignment of young asymptomatic adults

Purpose Our study aims to describe the postural alignment of young asymptomatic subjects from head to feet from bi-planar standing full-body X-rays, providing database to compare to aging adults. Novelty resides in the inclusion of the head and lower limbs in the erected posture’s analysis. Methods For 69 young asymptomatic subjects (18–40 years old) 3D reconstructions of the head, spine, pelvis and lower limbs segments were performed from biplanar full-body X-rays. Usual studied spinal, pelvic and lower limbs’ parameters were computed in 3D, sagittal and frontal planes of the patient. Relationships between these parameters were investigated. Inclinations of different lines were studied to characterize the erected posture. Results Values found for spinal curvatures, pelvic parameters and lower limbs geometrical parameters agreed with the literature: thoracic kyphosis, lumbar lordosis, pelvic incidence, pelvic tilt and sagittal vertical axis were respectively in average of 26.9 (SD 7.2 ), 30.5 (SD 7.5 ), 51.0 (SD 9.4 ), 11.1 (SD 5.6 ) and -8.9 mm (SD 21.6 mm). The angle between the vertical and the line joining the most superior point of dentiform apophyse of C2 (OD) and the center of the bi-coxofemoral axis (HA) was the less variable one (SD 1.6 ). Conclusions This study on 3D postural alignment reports the geometry of the spine, pelvis and lower limbs, of the young asymptomatic adult. The less variable angle is the one of the line OD–HA with the vertical, highlighting the vertical alignment of the head above the pelvis. This study provides a basis for future comparisons when investigating aging populations.Authors thank the ParisTech BiomecAM chair program on subject-specific musculoskeletal modeling, and in particular COVEA and Société Générale

CT-based semi-automatic quantification of vertebral fracture restoration

Minimally invasive surgeries aiming to restore fractured vertebral body are increasing; therefore, our goals were to create a 3D vertebra reconstruction process and design clinical indices to assess the vertebral restoration in terms of heights, angles and volumes. Based on computed tomography (CT)-scan of the vertebral spine, a 3D reconstruction method as well as relevant clinical indices were developed. First, a vertebra initial solution requiring 5 min of manual adjustments is built. Then an image processing algorithm places this solution in the CT-scan images volume to adjust the model's nodes. On the vertebral body's anterior and posterior parts, nine robust heights, volume and endplate angle measurement methods were developed. These parameters were evaluated by reproducibility and accuracy studies. The vertebral body reconstruction accuracy was 1.0 mm; heights and volume accuracy were, respectively, 1.2 and 179 mm3. In conclusion, a 3D vertebra reconstruction process requiring little user time was proposed as well as 3D clinical indices assessing fractured and restored vertebra

Volume and fat infiltration of spino-pelvic musculature in adults with spinal deformity.

AIM: To investigate fat infiltration and volume of spino-pelvic muscles in adults spinal deformity (ASD) with magnetic resonance imaging (MRI) and 3D reconstructions. METHODS: Nineteen female ASD patients (mean age 60 ± 13) were included prospectively and consecutively and had T1-weighted Turbo Spin Echo sequence MRIs with Dixon method from the proximal tibia up to T12 vertebra. The Dixon method permitted to evaluate the proportion of fat inside each muscle (fat-water ratio). In order to investigate the accuracy of the Dixon method for estimating fat vs water, the same MRI acquisition was performed on phantoms of four vials composed of different proportion of fat vs water. With Muscl'X software, 3D reconstructions of 17 muscles or group of muscles were obtained identifying the muscle's contour on a limited number of axial images [Deformation of parametric specific objects (DPSO) Method]. Musclar volume (Vmuscle), infiltrated fat volume (Vfat) and percentage of fat infiltration [Pfat, calculated as follow: Pfat = 100 × (Vfat/Vmuscle)] were characterized by extensor or flexor function respectively for the spine, hip and knee and theirs relationship with demographic data were investigated. RESULTS: Phantom acquisition demonstrated a non linear relation between Dixon fat-water ratio and the real fat-water ratio. In order to correct the Dixon fat-water ratio, the non linear relation was approximated with a polynomial function of degree three using the phantom acquisition. On average, Pfat was 13.3% ± 5.3%. Muscles from the spinal extensor group had a Pfat significantly greater than the other muscles groups, and the largest variability (Pfat = 31.9% ± 13.8%, P < 0.001). Muscles from the hip extensor group ranked 2(nd) in terms of Pfat (14% ± 8%), and were significantly greater than those of the knee extensor (P = 0.030). Muscles from the knee extensor group demonstrated the least Pfat (12% ± 8%). They were also the only group with a significant correlation between Vmuscle and Pfat (r = -0.741, P < 0.001), however this correlation was lacking in the other groups. No correlation was found between the Vmuscle total and age or body mass index. Except for the spine flexors, Pfat was correlated with age. Vmuscle and Vfat distributions demonstrated that muscular degeneration impacted the spinal extensors most. CONCLUSION: Mechanisms of fat infiltration are not similar among the muscle groups. Degeneration impacted the spinal and hip extensors most, key muscles of the sagittal alignment

Lumbar spinal muscles and spinal canal study by MRI three-dimensional reconstruction in adult lumbar spinal stenosis

Background: Lumbar spinal stenosis is degenerative disc disease most common manifestation. If stenosisdegree seems poorly related to symptom severity, lumbar muscles role is recognized. Many studiesreport imaging methods, to analyze muscle volumes and fat infiltration (FI), but remain limited due tothe difficulty to represent entire muscle volume variability. Recently a 3D muscle reconstruction protocol(using the deformation of a parametric specific object method (DPSO) and three-point Dixon images) wasreported. It offers the ability to evaluate, muscles volumes and muscle FI.Purpose: To describe, in a lumbar spinal stenosis population, muscle volumes, muscle FI and lumbarspinal canal volume with 3D MRI images reconstructions.Materials and methods: Ten adults presenting L4–L5 lumbar stenosis, were included. After specific MRIprotocol, three-dimensional, muscle and spinal canal, reconstructions were performed. Muscle (psoasand paraspinal muscles) volumes and fat infiltration (FI), the spinal canal volume, age, and height werecorrelated one to each other with Spearman correlation factor. An ANOVA was performed to evaluate theintervertebral level influence (P ≤ 0.05).Results: Muscle volumes correlated with height (r = 0.68 for psoas). Muscles FI correlated with age (r = 0.66for psoas) and lumbar spinal canal volume (r = 0.91). Psoas and paraspinal volumes were maximum atL3–L4 level whereas FI increased from L1–L2 to L5–S1 level.Discussion: These first results illustrate the importance to consider muscles entirely and report correla-tions between muscles FI, lumbar spinal canal volume and age; and between muscle volumes and patientsheight. Muscle degeneration seems more related to muscle FI than muscle volume.Level of evidence: 3.The authors declare that they have no competing interest

Conservative treatment of pediatric thoracic and lumbar spinal fractures

To assess sagittal plane spinopelvic balance and functional outcomes in a pediatric cohort of patients with a thoracic and/or a lumbar fracture treated conservatively. A multicentric study retrospectively reviewed radiological and functional outcomes (mean follow-up 49 months) of 48 patients (mean age 12 years) with thoracic and/or lumbar spinal fractures that occurred between 1996 and 2014. Demographic data and radiological spinopelvic parameters were analyzed. Functional outcome was evaluated by a telephone interview. First, a comparison between the initial and the last follow-up full-spine radiographs was performed for the assessment of bone remodeling and sagittal plane balance. Then, patients were classified into two groups (group 1: Risser≤2 and group 2, Risser>2) to assess the influence of skeletal maturity on the restoration of a correct sagittal balance. A total of 62% of the patients were at skeletal maturity at the final follow-up (Risser 4 and 5). Patients with a Risser grade of 2 or less had a higher remodeling potential. The mean residual local kyphosis in thoracic and lumbar fractures was, respectively, 8.2° and 8.7°. The mean thoracic global kyphosis remains stable at the last follow-up, in contrast to lumbar lordosis, which increased significantly. Sagittal plane global measurements on the basis of the C7-plumbline remained unchanged at the last follow-up. There was no change in the pelvic parameters, except for the sacral slope in the group 1 for patients with a lumbar fracture. The current study confirms a greater correction in younger patients (Risser≤2) in spinal fractures and reported that thoracic fractures have a higher remodeling potential than lumbar fracture. A local kyphosis of almost 10° remained at the last follow-up. However, no deterioration in the sagittal plane balance was found. This suggests compensatory mechanisms in adjacent structures for children and adolescents and excludes the only hypothesis of bone remodeling

Anterior Bone Loss in Cervical Disc Arthroplasty

Study Design Retrospective, longitudinal observational study. Purpose To describe the natural history of anterior bone loss (ABL) in cervical disc arthroplasty (CDA) and introduce a classification system for its assessment. Overview of Literature ABL has recently been recognized as a complication of CDA, but its cause and clinical effects remain unknown. Methods Patients with non-keeled CDA (146) were retrospectively reviewed. X-rays were examined at 6 weeks, 3, 6, 9, 12, 18, and 24 months, and annually thereafter for a minimum of 5 years. These were compared with the initial postoperative X-rays to determine the ABL. Visual Analog Scale pain scores were recorded at 3 months and 5 years. Neck Disability Index was recorded at postoperative 5 years. The natural history was determined and a classification system was introduced. Results Complete radiological assessment was available for 114 patients with 156 cervical disc replacements (CDRs) and 309 endplates (average age, 45.3 years; minimum, 28 years; maximum, 65 years; 57% females). ABL occurred in 57.1% of CDRs (45.5% mild, 8.3% moderate, and 3.2% severe) and commenced within 3 months of the operation and followed a benign course, with improvement in the bone stock after initial bone resorption. There was no relationship between ABL degree and pain or functional outcome, and no implants were revised. Conclusions ABL is common (57.1%). It occurs at an early stage (within 3 months) and typically follows a non-progressive natural history with stable radiographic features after the first year. Most ABL cases are mild, but severe ABL occurs in approximately 3% of CDAs. ABL does not affect the patients’ clinical outcome or the requirement for revision surgery. Surgeons should thus treat patients undergoing CDA considering ABL