Thesis (M.S.)--University of Michigan, 1987.

Thesis (M.S.)--University of Michigan, 1987.

Thesis (doctoral)--University of Uppsala, 1983. / Includes bibliographical references (p. 17-19).

The human foot is a biomechanical marvel which forms the distal link in the lower limb kinematic chain. With its small polyarticular construct and flexibility, it supports the body and provides balance during walking. The first metatarsophalangeal joint (MTPJ) is a vital joint in the forefoot for normal load transmission and energy efficient locomotion. Albeit a lot in literature about this joint, paucity still exists in the biomechanical aspects. Also, there is a speculation in the biomechanical world that the time integral component of pressure recorded from the plantar pressure measuring devices maybe representative of the shear force recorded from force platforms. The aim of the current study was to quantify the kinematics of the first MTPJ in three dimensions and the pedobarographic data under the first MTPJ during each sub-phase of stance in the gait cycle of normal subjects and to assess the correlation between the shear force from the force plate of the motion capture system with the variables from the barefoot plantar pressure measuring device. Similar quantification will be undertaken for the patients with isolated hallux rigidus. After obtaining ethical approval, 40 normal subjects (80 feet) and 6 patients with varying grades of hallux rigidus were recruited for the study. The equipment used to collect data included the Vicon® motion analysis system, AMTI® force plate and the emed® plantar pressure measuring device. Various checks were performed to establish the reliability of the system setup. Four trials from each foot were taken. Of the 320 total trials from the normal subjects, the trial numbers varied for specific tasks as some trials which were suitable for testing one objective might not be suitable for testing the other. One of the patients’ data could not be used as the data quality was below par due to issues with marker tracking. The correlation between the shear force from the force plate and the anthropometric measurements/parameters from the plantar pressure measuring device was performed using the statistical regression model. The Vicon® data of the whole stance phase revealed that the first MTPJ’s sagittal plane motion ranged from 9° of plantarflexion to 53° of dorsiflexion. In the coronal plane, the maximum pronation was 34° and supination was 31°. In the transverse plane, the maximum varus was 11° and the valgus was 24°. There were two dorsiflexion peaks; one at the Initial contact and the other at Pre-swing. The joint moved from supination to pronation and varus to valgus during the progression of stance phase from Initial contact to Pre-swing. Considering the emed®-m, there were four basic parameters namely the force, area, peak pressure and maximum mean pressure from which the other parameters were derived. Only the basic parameters accounted for the sub-phases of stance and it came to light that the force under the first MTPJ was maximum in the terminal stance (22.1%). For the whole stance phase, the first MTPJ contributed about 11% of the contact area, 14.5% of the mean area, 24% of the maximum force, 56% of the peak pressure, 63% of maximum mean pressure, 44% of Pressure-time integral, 14% of Force-time integral and 14% of mean force. The correlation equation with reasonable number of dependent variables obtained by the statistical regression model could account for only 46% of the shear force. Among the paired correlation equations with single dependent variable, the one with the mean force was the best and even this could only account for 31.1% of the shear force. Albeit 3 patients were having similar radiological grading of the pathology and 2 others falling into another grade, their objective data were diverse and couldn’t be grouped together. The normal kinematics of the first MTPJ and the pedobarographic data under the first MTPJ were quantified during each subphase of stance. Attempt to use one system alone instead of two to calculate the shear force did not provide satisfactory results. The patients’ data questions the use of radiology alone in deciding the management plan which is a common scenario in the current clinical setting.

No description available.

Thesis (M.S.)--Medical College of Ohio, 2005. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Major advisor: Nabil Ebraheim. Includes abstract. Document formatted into pages: iii, 57 p. Title from title page of PDF document. Bibliography: pages 35-42,49-56.

Baigiamajame magistro darbe yra atliekamas apatinių galūnių įtvarų ilgaamžiškumo tyrimas. Yra iškeliama čiurnos sąnario įtvarų patvarumo problema ir sudaroma jos sprendimo metodika. Darbe yra atliekama čiurnos sąnario biomechanikos analizė, įtvarų konstrukcijų ir medžiagų analizė, nagrinėjama ilgaamžiškumo reikšmė ir tyrimo būdai. Sudaroma tyrimo metodika. Kompiuterinio modeliavimo būdu, panaudojant SolidWorks programinę įrangą, yra sudaromas įtvaro modelis, nustatomos veikiančios apkrovos, atliekami įtempių ir poslinkių pasiskirstymo tyrimai. Atliekami modelio nuovargio bandymai. Atsižvelgiant į tyrimų rezultatus, yra sudaromi įtvarų iš aukštos temperatūros plastikų tinkamo pritaikymo nurodymai. Pateikiamos išvados ir literatūros sąrašas. / Final thesis presents the research of durability of lower limbs splints. The problem of fatigue behaviour of ankle joint splint is raised and its solution is suggested. Final thesis contains ankle joint biomechanics analysis, lower limbs splints design and material analysis. Review of durability research methods is also done. The methodology of research is arranged. Using the computer aided modeling with SolidWorks software the model of ankle joint splint is created. Load parameters are determined, research of stresses and deformations are performed. Fatigue test is also performed. Due to the results of research, the instructions for ankle joint splints made of high density polyethylene and polypropylene use and adaptation are listed. Final thesis also contains conclusions and list of literature. Size of work – 77 pages of text without attachments, 55 pictures, 9 tables and 25 bibliographical sources.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 5 uppsatser.

Articular cartilage covers the articulating ends of diarthrodial joints. It plays a vital role in the function of the musculoskeletal system by allowing almost frictionless motion to occur between the articular surfaces of a diarthrodial joint. Study of cartilage contact behavior will help to understand the intrinsic biomechanical properties related to cartilage degeneration and related pathology. In order to study the mechanical behavior of the cartilage a FEM based computational model of the knee-joint was developed from MRI data. A heuristic algorithm was developed based on Image processing techniques using Evolve2D toolbox and edge detection. An indigenous path following algorithm to capture minute details of bone and soft tissue curvature was developed using Image Processing Toolbox of Matlab. Parts including femur, tibia, femoral and tibial cartilages, lateral & medial menisci were extracted as a point cloud from each of the slices and rendered into a 3D model using GUI driven CAD package RHINOCEROS 4.0. Commercial FE software HYPERMESH 9.0 was used to develop FE model from geometric model. Cartilage and Menisci were modeled using eight node hexahedral elements and bones were modeled using four node quadrilateral elements. Bones were assumed to be rigid. Cartilage and menisci were assumed to be linearly elastic, isotropic and homogenous. The knee joint was subjected to a uniaxial compressive load with tibia remaining fixed and femur subjected to two primary boundary conditions: 1.Flexion - extension and Varus - Valgus rotation constrained; 2.Only Varus - Valgus rotation constrained. Parameters such as contact area, contact pressure, contact force, centre of contact pressure, mises stress distribution; maximum and minimum principal stresses were studied at maximum compressive load condition and also in intermittent steps. This model considered both geometric and contact non-linearity. From the FE analysis, it was observed that peak contact deformation and contact area on both femoral and tibial medial cartilage was found to be greater than the lateral side under full extension condition. More than 50% of the load transmission was through the medial side - which could be an indication of cartilage degeneration. Deformation of lateral meniscus was more than the medial meniscus under angular constrained conditions. Loading history during intermittent steps suggested that contact area on lateral tibial cartilage increased with load, indicating joint asymmetry. These results indicate the importance of the rotational constraints (boundary conditions) and represent more accurate physiological behavior of knee joint. Role of menisci in this study was analyzed, which indicated that consideration of menisci is essential in biomechanical estimation of load transmission. In conclusion, detailed segmentation to develop geometric model, precise boundary conditions & time dependent behavior of cartilage and menisci helped in understanding knee joint load bearing capacity to a better accuracy and can potentially give rise to designing better cartilage implants.