A. Aalsma - Academia.edu (original) (raw)
Papers by A. Aalsma
Archives of Orthopaedic and Trauma Surgery, 2010
Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. ... more Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. Only when the anatomical reduction is secured by stable fixation, revascularisation of the femoral head can take place and the fracture can heal by primary osteonal reconstruction. The common implants lack rotational and/or angular stability. Also the relative large volume of the implants within the femoral head compromises the (re)vascularisation. The combination of an anatomical reduction and a low volume, dynamic implant, providing angular and rotational stability seem to be crucial factors in the treatment of intracapsular hip fractures. This assumption formed the starting point for the development of the dynamic locking blade plate (DLBP), a new implant for the internal fixation of intracapsular hip fractures. This report describes the first clinical results of the new implant. Patients and methods Internal fixation with the DLBP was performed in 25 consecutive patients with an intracapsular hip fracture within 24 h from admission. Failure of fixation, due to non-union, avascular necrosis, implant failure or secondary displacement of the fracture, was the primary outcome measurer. Functional outcome was assessed by the Harris Hip Score. Results Following internal fixation of intracapsular hip fractures with the DLBP, a failure rate of 2 out of 25 patients and excellent functional results were seen after a follow-up of more than 2 years. Conclusion The initial clinical results of the DLBP are promising and justify the start of a randomised controlled trial.
Clinical Biomechanics, 2019
Background: The forces acting on the human clavicle in vivo are difficult if not impossible to me... more Background: The forces acting on the human clavicle in vivo are difficult if not impossible to measure. The goal of this study is to quantify the forces acting on the human clavicle during shoulder abduction, forward humeral elevation and three activities of daily living using the Delft Shoulder and Elbow Model. Methods: The Delft Shoulder and Elbow Model and a computed tomography scan of a clavicle were used to calculate the forces and moments acting on the entire clavicle and on three planes within the middle third of the clavicle during the simulated movements. Findings: The largest resultant force simulated across the clavicle was 126 N during abduction. Maximum resultant moments of 2.4 Nm were identified during both abduction and forward humeral elevation. The highest forces in the middle third of the clavicle were of a compressive nature along the longitudinal axis of the clavicle, increasing to 97 N during forward humeral elevation and 91 N during abduction. Forces in opposite direction along the y-axis were identified on either side of the conoid ligament. The three simulated activities of daily living had similar ranges of forces and moments irrespective of the sagittal plane in which these activities were performed. Interpretation: Peak forces occurred at different locations on the middle third of the clavicle during different movements. The results create an understanding of the forces and their distribution across the clavicle during activities of daily living. These data may be helpful in the development of clavicular fixation devices. Level of evidence: Biomechanical study.
2007 IEEE 10th International Conference on Rehabilitation Robotics, 2007
... Impedance forces due to inertia of the exoskeleton and friction of the base will cause some .... more ... Impedance forces due to inertia of the exoskeleton and friction of the base will cause some ... upper arm, the rotation can be measured and controlled, for instance by an active actuator or ... Via controlling the brake pressure via electric motors in a series elastic configuration [38], [39 ...
2007 IEEE 10th International Conference on Rehabilitation Robotics, 2007
In most upper-extremity rehabilitation robotics, several components affect the therapy outcome. A... more In most upper-extremity rehabilitation robotics, several components affect the therapy outcome. A common component is gravity compensation which alleviates upperextremity movements. Gravity compensation by itself could improve motor control further or faster, separate from other effects of robotic therapy. To investigate the rehabilitation value of gravity compensation separately, we created the dedicated gravity compensation system, Freebal.
IEEE Transactions on Biomedical Engineering, 2000
The goal of this study was to validate the suitability of a novel rotational hydroelastic actuato... more The goal of this study was to validate the suitability of a novel rotational hydroelastic actuator (rHEA) for use in our new rehabilitation exoskeleton for the upper limbs, the Limpact. The rHEA consists of a rotational hydraulic actuator and a customdesigned symmetric torsion spring in a series-elastic configuration. For rehabilitation therapy and impairment quantification, both compliant impedance control and stiff admittance control modes are possible. In the validation experiments, the torque bandwidth of the rHEA was limited to 18 Hz for a desired 20 N·m reference signal (multisine, constant spectrum) due the transport delays in the long flexible tubes between the valve and cylinder. These transport delays also required changes to existing theoretical models to better fit the models on the measured frequency response functions. The (theoretical) measurable torque resolution was better than 0.01 N·m and the (validated) delivered torque resolution below 1 N·m. After the validation experiments, further iterative improvements resulted in a spring design capable of a maximum output torque of 50 N·m with an intrinsic stiffness of 150 N·m/rad and a slightly higher bandwidth. With the design locked, the maximum measurable isometric torque is 100 N·m. In conclusion, the rHEA is suitable for upper limb rehabilitation therapy as it matches the desired performance. Braak and A. M. M. Aalsma are with BAAT Medical, Twekkelerweg 263, 7553 LZ Hengelo (OV),
Archives of Orthopaedic and Trauma Surgery, 2011
Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. ... more Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. Only when the anatomical reduction is secured by stable fixation, revascularisation of the femoral head can take place and the fracture can heal by primary osteonal reconstruction. The common implants lack rotational and/or angular stability. Also the relative large volume of the implants within the femoral head compromises the (re)vascularisation. The combination of an anatomical reduction and a low volume, dynamic implant, providing angular and rotational stability seem to be crucial factors in the treatment of intracapsular hip fractures. This assumption formed the starting point for the development of the dynamic locking blade plate (DLBP), a new implant for the internal fixation of intracapsular hip fractures. This report describes the first clinical results of the new implant. Patients and methods Internal fixation with the DLBP was performed in 25 consecutive patients with an intracapsular hip fracture within 24 h from admission. Failure of fixation, due to non-union, avascular necrosis, implant failure or secondary displacement of the fracture, was the primary outcome measurer. Functional outcome was assessed by the Harris Hip Score. Results Following internal fixation of intracapsular hip fractures with the DLBP, a failure rate of 2 out of 25 patients and excellent functional results were seen after a follow-up of more than 2 years. Conclusion The initial clinical results of the DLBP are promising and justify the start of a randomised controlled trial.
Wear, 1998
The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov ... more The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The
![Research paper thumbnail of A completely intramedullary leg lengthening device [using SMA actuator]](https://attachments.academia-assets.com/43951522/thumbnails/1.jpg)
](Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286), 1998
The procedure and the external fixator for lengthening long bones was developed by G. A. Ilizarov... more The procedure and the external fixator for lengthening long bones was developed by G. A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for the patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The device developed at the Laboratory of Biomechanical Engineering, University of Twente, is a telescopic intramedullary nail with a maximum diameter of 13 mm, which can be lengthened with 0.5 mm steps induced by a Shape Memory Alloy Actuator. The electrical energy for the actuator is supplied from outside the body by inductive coupling of two solenoid coils. Internaly, the electrical energy is transformed to thermal energy by Thermofoils and Peltierelements.
Technology and health care : official journal of the European Society for Engineering and Medicine, 1999
The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov ... more The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for the patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The device developed at the Laboratory of Biomechanical Engineering, University of Twente, is a telescopic intramedullary nail with a maximum diameter of 13 mm, which can be lengthened with 0.5 mm steps induced by a shape memory alloy actuator. The electrical energy for the actuator is supplied from outside the body by inductive coupling of two solenoid coils. Internally, the electrical energy is transformed to thermal energy by Thermofoils and Peltier-elements.
Le Journal de Physique IV, 1997
Today's medical technology makes it possible to increase leg length for people with leg length di... more Today's medical technology makes it possible to increase leg length for people with leg length discrepancies or excessively short limbs. With the Ilizarov method bones can be gradually elongated (max. Immlday) without implantation of bone grafts or multiple operations. Although the operative procedure is relatively simple, the negative side effects for the patient are considerable. An external fixator is mounted to the bone. The fixation is made by pins through the skin. Amongst the disadvantages of the external fixator are possible infection of the bone or soft tissue, minimal weight bearing and restricted possibility for wearing clothes. A design for a fully implantable extractor is proposed in order to eliminate these disadvantages for the patient.
Archives of Orthopaedic and Trauma Surgery, 2010
Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. ... more Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. Only when the anatomical reduction is secured by stable fixation, revascularisation of the femoral head can take place and the fracture can heal by primary osteonal reconstruction. The common implants lack rotational and/or angular stability. Also the relative large volume of the implants within the femoral head compromises the (re)vascularisation. The combination of an anatomical reduction and a low volume, dynamic implant, providing angular and rotational stability seem to be crucial factors in the treatment of intracapsular hip fractures. This assumption formed the starting point for the development of the dynamic locking blade plate (DLBP), a new implant for the internal fixation of intracapsular hip fractures. This report describes the first clinical results of the new implant. Patients and methods Internal fixation with the DLBP was performed in 25 consecutive patients with an intracapsular hip fracture within 24 h from admission. Failure of fixation, due to non-union, avascular necrosis, implant failure or secondary displacement of the fracture, was the primary outcome measurer. Functional outcome was assessed by the Harris Hip Score. Results Following internal fixation of intracapsular hip fractures with the DLBP, a failure rate of 2 out of 25 patients and excellent functional results were seen after a follow-up of more than 2 years. Conclusion The initial clinical results of the DLBP are promising and justify the start of a randomised controlled trial.
Clinical Biomechanics, 2019
Background: The forces acting on the human clavicle in vivo are difficult if not impossible to me... more Background: The forces acting on the human clavicle in vivo are difficult if not impossible to measure. The goal of this study is to quantify the forces acting on the human clavicle during shoulder abduction, forward humeral elevation and three activities of daily living using the Delft Shoulder and Elbow Model. Methods: The Delft Shoulder and Elbow Model and a computed tomography scan of a clavicle were used to calculate the forces and moments acting on the entire clavicle and on three planes within the middle third of the clavicle during the simulated movements. Findings: The largest resultant force simulated across the clavicle was 126 N during abduction. Maximum resultant moments of 2.4 Nm were identified during both abduction and forward humeral elevation. The highest forces in the middle third of the clavicle were of a compressive nature along the longitudinal axis of the clavicle, increasing to 97 N during forward humeral elevation and 91 N during abduction. Forces in opposite direction along the y-axis were identified on either side of the conoid ligament. The three simulated activities of daily living had similar ranges of forces and moments irrespective of the sagittal plane in which these activities were performed. Interpretation: Peak forces occurred at different locations on the middle third of the clavicle during different movements. The results create an understanding of the forces and their distribution across the clavicle during activities of daily living. These data may be helpful in the development of clavicular fixation devices. Level of evidence: Biomechanical study.
2007 IEEE 10th International Conference on Rehabilitation Robotics, 2007
... Impedance forces due to inertia of the exoskeleton and friction of the base will cause some .... more ... Impedance forces due to inertia of the exoskeleton and friction of the base will cause some ... upper arm, the rotation can be measured and controlled, for instance by an active actuator or ... Via controlling the brake pressure via electric motors in a series elastic configuration [38], [39 ...
2007 IEEE 10th International Conference on Rehabilitation Robotics, 2007
In most upper-extremity rehabilitation robotics, several components affect the therapy outcome. A... more In most upper-extremity rehabilitation robotics, several components affect the therapy outcome. A common component is gravity compensation which alleviates upperextremity movements. Gravity compensation by itself could improve motor control further or faster, separate from other effects of robotic therapy. To investigate the rehabilitation value of gravity compensation separately, we created the dedicated gravity compensation system, Freebal.
IEEE Transactions on Biomedical Engineering, 2000
The goal of this study was to validate the suitability of a novel rotational hydroelastic actuato... more The goal of this study was to validate the suitability of a novel rotational hydroelastic actuator (rHEA) for use in our new rehabilitation exoskeleton for the upper limbs, the Limpact. The rHEA consists of a rotational hydraulic actuator and a customdesigned symmetric torsion spring in a series-elastic configuration. For rehabilitation therapy and impairment quantification, both compliant impedance control and stiff admittance control modes are possible. In the validation experiments, the torque bandwidth of the rHEA was limited to 18 Hz for a desired 20 N·m reference signal (multisine, constant spectrum) due the transport delays in the long flexible tubes between the valve and cylinder. These transport delays also required changes to existing theoretical models to better fit the models on the measured frequency response functions. The (theoretical) measurable torque resolution was better than 0.01 N·m and the (validated) delivered torque resolution below 1 N·m. After the validation experiments, further iterative improvements resulted in a spring design capable of a maximum output torque of 50 N·m with an intrinsic stiffness of 150 N·m/rad and a slightly higher bandwidth. With the design locked, the maximum measurable isometric torque is 100 N·m. In conclusion, the rHEA is suitable for upper limb rehabilitation therapy as it matches the desired performance. Braak and A. M. M. Aalsma are with BAAT Medical, Twekkelerweg 263, 7553 LZ Hengelo (OV),
Archives of Orthopaedic and Trauma Surgery, 2011
Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. ... more Introduction The osteosynthesis of intracapsular hip fractures results in a 19-48% failure rate. Only when the anatomical reduction is secured by stable fixation, revascularisation of the femoral head can take place and the fracture can heal by primary osteonal reconstruction. The common implants lack rotational and/or angular stability. Also the relative large volume of the implants within the femoral head compromises the (re)vascularisation. The combination of an anatomical reduction and a low volume, dynamic implant, providing angular and rotational stability seem to be crucial factors in the treatment of intracapsular hip fractures. This assumption formed the starting point for the development of the dynamic locking blade plate (DLBP), a new implant for the internal fixation of intracapsular hip fractures. This report describes the first clinical results of the new implant. Patients and methods Internal fixation with the DLBP was performed in 25 consecutive patients with an intracapsular hip fracture within 24 h from admission. Failure of fixation, due to non-union, avascular necrosis, implant failure or secondary displacement of the fracture, was the primary outcome measurer. Functional outcome was assessed by the Harris Hip Score. Results Following internal fixation of intracapsular hip fractures with the DLBP, a failure rate of 2 out of 25 patients and excellent functional results were seen after a follow-up of more than 2 years. Conclusion The initial clinical results of the DLBP are promising and justify the start of a randomised controlled trial.
Wear, 1998
The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov ... more The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The
Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286), 1998
The procedure and the external fixator for lengthening long bones was developed by G. A. Ilizarov... more The procedure and the external fixator for lengthening long bones was developed by G. A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for the patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The device developed at the Laboratory of Biomechanical Engineering, University of Twente, is a telescopic intramedullary nail with a maximum diameter of 13 mm, which can be lengthened with 0.5 mm steps induced by a Shape Memory Alloy Actuator. The electrical energy for the actuator is supplied from outside the body by inductive coupling of two solenoid coils. Internaly, the electrical energy is transformed to thermal energy by Thermofoils and Peltierelements.
Technology and health care : official journal of the European Society for Engineering and Medicine, 1999
The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov ... more The procedure and the external fixator for lengthening long bones was developed by G.A. Ilizarov in the late 1960's. This technique has, despite its proven abilities for leg lengthening and correction of angular deformities, some considerable disadvantages for the patients. Discomfort, infections and restricted weight bearing are some reasons for the development of a completely intramedullary device for leg lengthening. The device developed at the Laboratory of Biomechanical Engineering, University of Twente, is a telescopic intramedullary nail with a maximum diameter of 13 mm, which can be lengthened with 0.5 mm steps induced by a shape memory alloy actuator. The electrical energy for the actuator is supplied from outside the body by inductive coupling of two solenoid coils. Internally, the electrical energy is transformed to thermal energy by Thermofoils and Peltier-elements.
Le Journal de Physique IV, 1997
Today's medical technology makes it possible to increase leg length for people with leg length di... more Today's medical technology makes it possible to increase leg length for people with leg length discrepancies or excessively short limbs. With the Ilizarov method bones can be gradually elongated (max. Immlday) without implantation of bone grafts or multiple operations. Although the operative procedure is relatively simple, the negative side effects for the patient are considerable. An external fixator is mounted to the bone. The fixation is made by pins through the skin. Amongst the disadvantages of the external fixator are possible infection of the bone or soft tissue, minimal weight bearing and restricted possibility for wearing clothes. A design for a fully implantable extractor is proposed in order to eliminate these disadvantages for the patient.