Woo-Suck Han's research while affiliated with Université Jean Monnet and other places

Background: Although impairments in dorso-lumbar spine mobility have been previously reported in patients with low back pain, its exact mechanism is not yet clear. Therefore, the purpose of this systematic review and meta-analysis is to investigate and compare spinal kinematics between subjects with and without low back pain and identify appropriate tools to evaluate it. Methods: The PubMed, Scopus and Web of Science databases were searched for relevant literature. The search strategy was mainly focused on studies investigating lumbar kinematics in subjects with and without low back pain during clinical functional tests, gait, sports and daily functional activities. Papers were selected if at least one of these outputs was reported: lumbar range of motion, lumbar velocity, lumbar acceleration and deceleration, lordosis angle or lumbar excursion. Findings: Among 804 papers, 48 met the review eligibility criteria and 29 were eligible to perform a meta-analysis. Lumbar range of motion was the primary outcome measured. A statistically significant limitation of the lumbar mobility was found in low back pain group in all planes, and in the frontal and transverse planes for thoracic range of motion, but there is no significant limitation for pelvic mobility. The amount of limitation was found to be more important in the lumbar sagittal plane and during challenging functional activities in comparison with simple activities. Interpretation: The findings of this review provide insight into the impact of low back pain on spinal kinematics during specific movements, contributing to our understanding of this relationship and suggesting potential clinical implications.

A comparative study of eight different lumbar belts, which are representative of the French market, was carried out on four typical morphologies of patients to assess their therapeutic effects and identify the correlation between the therapeutic parameters and mechanical ones. Four typical morphologies were chosen among 15 patients that had been chosen for the clinical study: tall-large, small-large, tall-thin, and small-thin. Simplified 3D finite elements (FE) models of the trunk according to each patient’s morphology were used for numerical analyses using Abaqus SimuliaTM. The same material properties of the body structures and boundary conditions were taken for all models to only focus on morphological variations. The material properties of eight lumbar belts were obtained by mechanical testing. The pressure applied by the belt to the trunk was modelled by Laplace’s law. The influences of belt types on typical morphologies were analyzed and synthetized to show which parameters are significant for biomechanical efficacy and attendance to the therapeutic effects. Finally, we found the following belt effects: (i) the lumbar belt is more efficient on the thin morphology than the large one, (ii) all mechanical values checked on the vertebral disks and vertebrae have a strong correlation with the correction of lordosis angle, and (iii) the belt’s global stiffness is an important parameter for generating the pressure applied to the trunk.

Objective: A numerical 3D model of the human trunk was developed to study the biomechanical effects of lumbar belts used to treat low back pain. Methods: This model was taken from trunk radiographies of a person and simplified so as to make a parametric study by varying morphological parameters of the patient, characteristic parameters of the lumbar belt and mechanical parameters of body and finally to determine the parameters influencing the effects of low back pain when of wearing the lumbar belt. The loading of lumbar belt is modelled by Laplace's law. These results were compared with clinical study. Results: All the results of this parametric study showed that the choice of belt is very important depending on the patient's morphology. Surprisingly, the therapeutic treatment is not influenced by the mechanical characteristics of the body structures except the mechanical properties of intervertebral discs. Discussion: The numerical model can serve as a basis for more in-depth studies concerning the analysis of efficiency of lumbar belts in low back pain. In order to study the impact of the belt's architecture, the pressure applied to the trunk modelled by Laplace's law could be improved. This model could also be used as the basis for a study of the impact of the belt over a period of wearing time. Indeed, the clinical study shows that movement has an important impact on the distribution of pressure applied by the belt.

The mechanical behavior of the foot is often studied through the movement of the segments composing it and not through the movement of each individual bone, preventing an accurate and unambiguous study of soft tissue strains and foot posture. In order to describe the internal behavior of the foot under static load, we present here an original methodology that automatically tracks bone positions and ligament deformations through a series of CT acquisitions for a foot under load. This methodology was evaluated in a limited clinical study based on three cadaveric feet in different static load cases, first performed with bare feet and then with a sports shoe to get first insights on how the shoe influences the foot's behavior in different configurations. A model-based tracking technique using hierarchical distance minimization was implemented to track the position of 28 foot bones for each subject, while a mesh-morphing technique mapped the ligaments from a generic model to the patient-specific model in order to obtain their deformations. Comparison of these measurements between the ex vivo loaded bare foot and the shod foot showed evidence that wearing a shoe affects the deformation of specific ligaments, has a significant impact on the relative movement of the bones and alters the posture of the foot skeleton (plantar-dorsal flexion, arch sagging, and forefoot abduction-adduction on the midfoot). The developed method may provide new clinical indicators to guide shoe design and valuable data for detailed foot model validation.

Objective: A numerical 3D model of the human trunk was developed to study the biomechanical effects of lumbar belts used to treat low back pain.

In this study, the movement of climbing a step is decomposed in 4 EOS images. A patient-dependent 3D model of the knee is then created from MRI, and several numerical simulations are carried out according to the experimental boundary conditions (force and flexion angle), so as to ensure the global knee mechanical equilibrium. To validate this patient-specific model, its bony structure is confronted with the EOS images once the mechanical equilibrium is reached. This model gave us an estimation of the stress in the ligaments for every flexion angle as well as a pressure map on the cartilages.