... from biodegradable cylinders X. Zhang", UP Wyss1', D. Pichora0, MFA... more ... from biodegradable cylinders X. Zhang", UP Wyss1', D. Pichora0, MFA Goosen3'-", A. Gonzal6 and CL Marte'1 Departments of ^Chemical Engineering, ''Mechanical Engineering and ... 10 R. Baker, Controlled Release of Biologically Active Agents, John Wiley & Sons, 1987. ...
ABSTRACT Objectives. To establish a database of upper limb kinematics and kinetics to support the... more ABSTRACT Objectives. To establish a database of upper limb kinematics and kinetics to support the development of a biomechanical model of the shoulder and elbow.Design. Ten unimpaired subjects were studied when performing 10 different tasks of every day living.Background. The development of biomechanical models of the upper limb to support the design of total joint replacements requires data on the commonly performed activities. Unlike the lower limb, this involves the selection of the tasks believed to be the most common.Methods. Kinematic data were collected using four video cameras to track the movements of reflective markers attached to the upper limb and trunk. The rigid body kinematics was then analysed and the external forces and moments at the shoulder and elbow were calculated using inverse dynamics.Results. The greatest ranges of motion at the shoulder occurred during reaching and lifting tasks as did the greatest shoulder moment (14.3 Nm flexion). The greatest elbow flexion occurred while reaching the back of the head but the greatest moment (5.8 Nm) occurred while lifting a block to head height.Conclusions. A database of ranges of motion and external forces and moments has been established to support the development of biomechanical models of the upper limb.RelevanceThe development of biomechanical models to support the design of upper limb joint replacements requires detailed knowledge of the types and magnitudes of forces and moments at the joints.
Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine, 2000
Interest in arm movements has increased tremendously in recent years. This interest has been moti... more Interest in arm movements has increased tremendously in recent years. This interest has been motivated by different goals: the desire for a more scientific approach to replacement or support of the joints of the upper limb, the need for input to biomechanical computer models, and the clinical interest in comparing normal movements with pathological movements. The availability of commercial marker-tracking systems has facilitated achieving these goals. However, the complex nature of arm movements and the lack of standardized movements raises many challenges. In comparison with gait analysis, few arm motion analyses have been conducted. The purpose of this review is to aid researchers and clinicians interested in conducting an arm motion study in choosing the appropriate methodology. This is accomplished both by describing the methods used in past investigations and by highlighting important findings. Due to the variety of research goals, there is sometimes more than one appropriate m...
The data relating to 155 patients reviewed at the Wilhelm Schulthess Clinic in Zurich (clinic of ... more The data relating to 155 patients reviewed at the Wilhelm Schulthess Clinic in Zurich (clinic of the originators of the GSB knee prosthesis) have been evaluated in the present study. The X-ray pictures of the patients with implanted GSB knee prostheses were studied up to ten years at 1–2 years' intervals on the basis of 45 characteristic dimensions. The 15000 measurements of the study have been evaluated by means of a computer. The paper describes the method used and reports the statistical results obtained.
Five activiti es of daily living were studied in order to determine the glenohumeral contact forc... more Five activiti es of daily living were studied in order to determine the glenohumeral contact forces during common high-load activities. These activities included standing up from and sitting down into a chair using the arms, walking with a cane, lif ting a 5 kg box using both hands and lifting a 10 kg suitcase. The movements and hand loads of six healthy older subjects were recorded with a motion analysis system from which trunk and arm joint angles were calculated. This information was input into a biomechanical model developed by Peterson et al. (1994). The resulting contact forces ranged from 0.3 to 6.9 times bodyweight with typical values ranging from two to three times bodyweight. The highest average contact force was associated with lifting a sui t- case. Since higher loads may be carried this is likely the most important task for high gleno- humeral contact forces. The contact force values should be used with caution as there is some con- cern about the validity of the model ...
Biomechanical analysis of the movement of the lumbar spinal nerve roots (NRs). The characteristic... more Biomechanical analysis of the movement of the lumbar spinal nerve roots (NRs). The characteristics of the movement of lumbar spinal NRs corresponding to the change of posture were three-dimensionally analyzed in nonsimulated and simulated adhesion conditions using a porcine model. There is a paucity of data on the movement of NRs. Thirty two NRs of four pig cadavers were investigated. (study 1) Two tantalum beads were sutured on respective NRs from L3 to L6. Five beads were put into each bony structure as reference points. The porcine body was put on the cage designed for three-dimensional radiostereometric analysis. Two oblique radiographs were simultaneously taken at flexion, neutral, and extension. (study 2) After study 1, either L4 NR was ligated onto the adjacent bone to mimic monoradicular adhesion. Radiographs were taken in the same manner. The movements of the beads on NRs relative to immobile standard points in each vertebra were analyzed. The movement of NRs was characterized as a combination of stretching/slackening and pendulum motion. The distance that NRs were stretched/slackened, the excursion, and the angles that NRs moved were: 0.39 +/- 0.29 mm, 1.81 +/- 0.63 mm, and 10.46 +/- 5.93 degrees (in nonadhesion), and 0.30 +/- 0.20 mm, 1.02 +/- 0.50 mm, and 7.13 +/- 3.79 degrees (in simulated adhesion), respectively. Adhesion might play a part in the pathogenesis of lumbar spinal disorders because mechanical irritation secondary to stretching/slackening and pendulum motion might be concentrated at the distal part of NRs, adjacent to adhesion site, which has less cerebrospinal fluid and is close to dorsal root ganglion.
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2005
Many experimental protocols for investigating articular cartilage mechanics have involved the use... more Many experimental protocols for investigating articular cartilage mechanics have involved the use of a freeze-thaw cycle for storage or tissue manipulation. It was hypothesized that mechanical properties are altered due to freeze-thaw cycling. The aim of this study, therefore, was to examine the possibility of protocol-induced artefacts in the mechanical properties of porcine articular cartilage specimens related specifically to freeze-thaw events. Twenty-eight osteochondral specimens [14 from the femoral condyles (FCs) and 14 from the patella-femoral (PF) groove] were tested in confined compression before and after being frozen at -20 degrees C for 7 days. The fluid-independent and fluid-dependent mechanical properties (aggregate modulus of the solid phase and the half-life of stress relaxation respectively) were determined and compared. The aggregate modulus decreased by 13.5 per cent and 20.1 per cent for the PF and FC regions respectively (p = 0.002) and the half-life of the stress relaxation at 10 per cent strain decreased by 6.4 per cent and 12.6 per cent for the PF and FC specimens respectively (p = 0.0341). In conclusion, it has been shown that the protocol used, which involved freezing to -20 degrees C and thawing after 7 days, caused artefacts in the mechanical properties of porcine osteochondral specimens. It is suggested that protocols requiring freezing must be critically reviewed to eliminate such artefacts.
... An investigation of the synthesis and thermal stability of poly(DL-lactide) ... Stannous octo... more ... An investigation of the synthesis and thermal stability of poly(DL-lactide) ... Stannous octoate (SigmaChemical Company, St. ... For the thermal degradability tests, polymer was put into a test tube, with one end open to air, for various times (5 to 30 minutes) at different temperatures ...
... from biodegradable cylinders X. Zhang", UP Wyss1', D. Pichora0, MFA... more ... from biodegradable cylinders X. Zhang", UP Wyss1', D. Pichora0, MFA Goosen3'-", A. Gonzal6 and CL Marte'1 Departments of ^Chemical Engineering, ''Mechanical Engineering and ... 10 R. Baker, Controlled Release of Biologically Active Agents, John Wiley & Sons, 1987. ...
ABSTRACT Objectives. To establish a database of upper limb kinematics and kinetics to support the... more ABSTRACT Objectives. To establish a database of upper limb kinematics and kinetics to support the development of a biomechanical model of the shoulder and elbow.Design. Ten unimpaired subjects were studied when performing 10 different tasks of every day living.Background. The development of biomechanical models of the upper limb to support the design of total joint replacements requires data on the commonly performed activities. Unlike the lower limb, this involves the selection of the tasks believed to be the most common.Methods. Kinematic data were collected using four video cameras to track the movements of reflective markers attached to the upper limb and trunk. The rigid body kinematics was then analysed and the external forces and moments at the shoulder and elbow were calculated using inverse dynamics.Results. The greatest ranges of motion at the shoulder occurred during reaching and lifting tasks as did the greatest shoulder moment (14.3 Nm flexion). The greatest elbow flexion occurred while reaching the back of the head but the greatest moment (5.8 Nm) occurred while lifting a block to head height.Conclusions. A database of ranges of motion and external forces and moments has been established to support the development of biomechanical models of the upper limb.RelevanceThe development of biomechanical models to support the design of upper limb joint replacements requires detailed knowledge of the types and magnitudes of forces and moments at the joints.
Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine, 2000
Interest in arm movements has increased tremendously in recent years. This interest has been moti... more Interest in arm movements has increased tremendously in recent years. This interest has been motivated by different goals: the desire for a more scientific approach to replacement or support of the joints of the upper limb, the need for input to biomechanical computer models, and the clinical interest in comparing normal movements with pathological movements. The availability of commercial marker-tracking systems has facilitated achieving these goals. However, the complex nature of arm movements and the lack of standardized movements raises many challenges. In comparison with gait analysis, few arm motion analyses have been conducted. The purpose of this review is to aid researchers and clinicians interested in conducting an arm motion study in choosing the appropriate methodology. This is accomplished both by describing the methods used in past investigations and by highlighting important findings. Due to the variety of research goals, there is sometimes more than one appropriate m...
The data relating to 155 patients reviewed at the Wilhelm Schulthess Clinic in Zurich (clinic of ... more The data relating to 155 patients reviewed at the Wilhelm Schulthess Clinic in Zurich (clinic of the originators of the GSB knee prosthesis) have been evaluated in the present study. The X-ray pictures of the patients with implanted GSB knee prostheses were studied up to ten years at 1–2 years' intervals on the basis of 45 characteristic dimensions. The 15000 measurements of the study have been evaluated by means of a computer. The paper describes the method used and reports the statistical results obtained.
Five activiti es of daily living were studied in order to determine the glenohumeral contact forc... more Five activiti es of daily living were studied in order to determine the glenohumeral contact forces during common high-load activities. These activities included standing up from and sitting down into a chair using the arms, walking with a cane, lif ting a 5 kg box using both hands and lifting a 10 kg suitcase. The movements and hand loads of six healthy older subjects were recorded with a motion analysis system from which trunk and arm joint angles were calculated. This information was input into a biomechanical model developed by Peterson et al. (1994). The resulting contact forces ranged from 0.3 to 6.9 times bodyweight with typical values ranging from two to three times bodyweight. The highest average contact force was associated with lifting a sui t- case. Since higher loads may be carried this is likely the most important task for high gleno- humeral contact forces. The contact force values should be used with caution as there is some con- cern about the validity of the model ...
Biomechanical analysis of the movement of the lumbar spinal nerve roots (NRs). The characteristic... more Biomechanical analysis of the movement of the lumbar spinal nerve roots (NRs). The characteristics of the movement of lumbar spinal NRs corresponding to the change of posture were three-dimensionally analyzed in nonsimulated and simulated adhesion conditions using a porcine model. There is a paucity of data on the movement of NRs. Thirty two NRs of four pig cadavers were investigated. (study 1) Two tantalum beads were sutured on respective NRs from L3 to L6. Five beads were put into each bony structure as reference points. The porcine body was put on the cage designed for three-dimensional radiostereometric analysis. Two oblique radiographs were simultaneously taken at flexion, neutral, and extension. (study 2) After study 1, either L4 NR was ligated onto the adjacent bone to mimic monoradicular adhesion. Radiographs were taken in the same manner. The movements of the beads on NRs relative to immobile standard points in each vertebra were analyzed. The movement of NRs was characterized as a combination of stretching/slackening and pendulum motion. The distance that NRs were stretched/slackened, the excursion, and the angles that NRs moved were: 0.39 +/- 0.29 mm, 1.81 +/- 0.63 mm, and 10.46 +/- 5.93 degrees (in nonadhesion), and 0.30 +/- 0.20 mm, 1.02 +/- 0.50 mm, and 7.13 +/- 3.79 degrees (in simulated adhesion), respectively. Adhesion might play a part in the pathogenesis of lumbar spinal disorders because mechanical irritation secondary to stretching/slackening and pendulum motion might be concentrated at the distal part of NRs, adjacent to adhesion site, which has less cerebrospinal fluid and is close to dorsal root ganglion.
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2005
Many experimental protocols for investigating articular cartilage mechanics have involved the use... more Many experimental protocols for investigating articular cartilage mechanics have involved the use of a freeze-thaw cycle for storage or tissue manipulation. It was hypothesized that mechanical properties are altered due to freeze-thaw cycling. The aim of this study, therefore, was to examine the possibility of protocol-induced artefacts in the mechanical properties of porcine articular cartilage specimens related specifically to freeze-thaw events. Twenty-eight osteochondral specimens [14 from the femoral condyles (FCs) and 14 from the patella-femoral (PF) groove] were tested in confined compression before and after being frozen at -20 degrees C for 7 days. The fluid-independent and fluid-dependent mechanical properties (aggregate modulus of the solid phase and the half-life of stress relaxation respectively) were determined and compared. The aggregate modulus decreased by 13.5 per cent and 20.1 per cent for the PF and FC regions respectively (p = 0.002) and the half-life of the stress relaxation at 10 per cent strain decreased by 6.4 per cent and 12.6 per cent for the PF and FC specimens respectively (p = 0.0341). In conclusion, it has been shown that the protocol used, which involved freezing to -20 degrees C and thawing after 7 days, caused artefacts in the mechanical properties of porcine osteochondral specimens. It is suggested that protocols requiring freezing must be critically reviewed to eliminate such artefacts.
... An investigation of the synthesis and thermal stability of poly(DL-lactide) ... Stannous octo... more ... An investigation of the synthesis and thermal stability of poly(DL-lactide) ... Stannous octoate (SigmaChemical Company, St. ... For the thermal degradability tests, polymer was put into a test tube, with one end open to air, for various times (5 to 30 minutes) at different temperatures ...
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