Advanced tuning of below knee prosthesis using the MOTEK CAREN system

A transtibial prosthetic alignment is described as a spatial three dimensions with six degrees of freedom of interrelationship between socket and foot. Moreover, dynamic alignment, a crucial step in aligning prosthesis, aims to achieve the most suitable limb position to achieve desire function and comfort. Misalignment may result in walking difficulty, skin abrasion and uneven forces acting on the residual limb within the socket, which could lead to wound, and even more serious skin and joint trauma. However, the optimal alignment in traditional practice can take one day to several weeks from the starting to finalize in dynamic alignment, depends on prosthetist’s skill and experience. The alignment optimization, a very time- consuming process, is accomplished by subjective judgment of the prosthetist based on visual observation of gait and feedback from the patient. Furthermore, a prosthesis aligned in the traditional subjective practice seems to be lacked of any scientific biomechanical systematics

The Vertical Ground Reaction Force and Temporal-Spatial Parameters of Transfemoral Amputees Wearing Three Prosthetic Knee Joints Available in Thailand: a Pilot Study

Objective: To examine the temporal-spatial characteristics of transfemoral amputees using three prosthetic knees available in Thailand. In addition, the estimated vertical Ground Reaction Force (vGRF) was explored, in particular the graphical differences in the M-shape of the vGRF pattern amongst each of the knees and the sound limb. Methods: Three transfemoral amputees were fitted with three different prosthetic knee joints (Chulalongkorn University (CU) Polycentric Knee Joint, Prosthesis Foundation Knee, Otto Bock 3R20) and performed walking trials while the vGRF and temporal-spatial parameters were collected for all participants. Results: Similarities existed amongst GRF metrics across all prosthetic knees. Stance and swing time in the CU Polycentric Knee Joint was similar to that of the sound limb. Walking speeds were highest in the Otto Bock 3R20 and lowest in the Prosthesis Foundation Knee. Conclusion: This preliminary pilot testing revealed similarities amongst all three prosthetic knees. Future research with more participants and additional analysis could further elucidate characteristics of these prosthetic knees

Advanced tuning of a trans-tibial prosthesis using motion capture and visualisation

A transtibial prosthetic alignment is a three dimensions interrelationship between a socket and a prosthetic foot. The prosthetic alignment aims to achieve the most suitable limb position for desired function and comfort. The alignment is tuned through three alignment stages; bench, static and dynamic until achieving the optimal alignment. However, the available instrumentation could not be used for assisting the prosthetist in aligning the prosthesis through all three alignment stages. This aims of this study were to investigate and develop a new alignment system that can assist the prosthetist in tuning the alignment of a trans-tibial prosthesis and to compare to Conventional Alignment Technique (ConAT). Four gait analysis protocols: Strathclyde Cluster Model (SCM), Human Body Model (HBM), Human Body Model 2 (HBM2) and Plug-in Gait (PiG) were investigated, and their reliability were explored in able-bodied and trans-tibial amputee (TTA) subjects. The SCM demonstrated good correlation, good repeatability, accuracy, and easy to use in both able-bodied and TTA subjects. The walking condition was considered as a crucial factor during gait analysis. Three walking conditions, Overground (OG), Fixed speed treadmill (FS TM) and Selfpaced treadmill (SP TM), were compared. Results demonstrated no significant difference between OG and SP TM. Therefore, SP TM can be used compatibly with OG. Furthermore, a Computerised motion capture and Visualisation system for the Assisted Alignment Technique (CVAT) was developed to read-outs of the alignment parameters in real-time. The SCM and prosthetic markers set were used to implement alignment visual feedback scenarios during three alignment stages. SP TM was used to assist alignment in the dynamic stage. Further, the CVAT was compared to the ConAT. Results of the CVAT method showed a positive effect on gait outcomes.In conclusion, the CVAT allows the prompt and qualitative prosthetic alignment and enables the prosthetist to align prosthesis objectively.A transtibial prosthetic alignment is a three dimensions interrelationship between a socket and a prosthetic foot. The prosthetic alignment aims to achieve the most suitable limb position for desired function and comfort. The alignment is tuned through three alignment stages; bench, static and dynamic until achieving the optimal alignment. However, the available instrumentation could not be used for assisting the prosthetist in aligning the prosthesis through all three alignment stages. This aims of this study were to investigate and develop a new alignment system that can assist the prosthetist in tuning the alignment of a trans-tibial prosthesis and to compare to Conventional Alignment Technique (ConAT). Four gait analysis protocols: Strathclyde Cluster Model (SCM), Human Body Model (HBM), Human Body Model 2 (HBM2) and Plug-in Gait (PiG) were investigated, and their reliability were explored in able-bodied and trans-tibial amputee (TTA) subjects. The SCM demonstrated good correlation, good repeatability, accuracy, and easy to use in both able-bodied and TTA subjects. The walking condition was considered as a crucial factor during gait analysis. Three walking conditions, Overground (OG), Fixed speed treadmill (FS TM) and Selfpaced treadmill (SP TM), were compared. Results demonstrated no significant difference between OG and SP TM. Therefore, SP TM can be used compatibly with OG. Furthermore, a Computerised motion capture and Visualisation system for the Assisted Alignment Technique (CVAT) was developed to read-outs of the alignment parameters in real-time. The SCM and prosthetic markers set were used to implement alignment visual feedback scenarios during three alignment stages. SP TM was used to assist alignment in the dynamic stage. Further, the CVAT was compared to the ConAT. Results of the CVAT method showed a positive effect on gait outcomes.In conclusion, the CVAT allows the prompt and qualitative prosthetic alignment and enables the prosthetist to align prosthesis objectively

Development of four-bar polycentric knee joint with stance-phase knee flexion

Abstract A conventional 4-bar polycentric knee and solid ankle cushion heel foot (SACH foot) have been commonly used in developing countries. However, they cannot perform stance-phase knee flexion, which makes a person with an amputation walk unnaturally and with less stability. This research proposes a novel design of a 4-bar polycentric knee with stance-phase knee flexion ability (4BSF), which can perform both stance and swing-phase knee flexion, like able-bodied gait. In the proposed conceptual design, the instantaneous center of rotation (ICR) path is repositioned during the stance phase. The ICR was placed in front of the ground reaction force (GRF) to initiate knee flexion during the loading response. The prototype was validated by a single-subject pilot study at the Gait analysis laboratory. The results showed that a person with an amputation walks with stance-phase knee flexion using the proposed 4BSF. The maximum knee flexion angle is more than 10° during the stance phase. Furthermore, when the 4BSF was used with a SACH foot, the amount of time to achieve the foot flat was shorter, and the foot flat duration time was twice as long as the conventional 4-bar polycentric knee

Validity and Reliability of Inertial Measurement Unit (IMU)-Derived 3D Joint Kinematics in Persons Wearing Transtibial Prosthesis

Background: A validity and reliability assessment of inertial measurement unit (IMU)-derived joint angular kinematics during walking is a necessary step for motion analysis in the lower extremity prosthesis user population. This study aimed to assess the accuracy and reliability of an inertial measurement unit (IMU) system compared to an optical motion capture (OMC) system in transtibial prosthesis (TTP) users. Methods: Thirty TTP users were recruited and underwent simultaneous motion capture from IMU and OMC systems during walking. Reliability and validity were assessed using intra- and inter-subject variability with standard deviation (S.D.), average S.D., and intraclass correlation coefficient (ICC). Results: The intra-subject S.D. for all rotations of the lower limb joints were less than 1° for both systems. The IMU system had a lower mean S.D. (o), as seen in inter-subject variability. The ICC revealed good to excellent agreement between the two systems for all sagittal kinematic parameters. Conclusion: All joint angular kinematic comparisons supported the IMU system’s results as comparable to OMC. The IMU was capable of precise sagittal plane motion data and demonstrated validity and reliability to OMC. These findings evidence that when compared to OMC, an IMU system may serve well in evaluating the gait of lower limb prosthesis users

Validity and Reliability of Inertial Measurement Unit (IMU)-Derived 3D Joint Kinematics in Persons Wearing Transtibial Prosthesis

Background: A validity and reliability assessment of inertial measurement unit (IMU)-derived joint angular kinematics during walking is a necessary step for motion analysis in the lower extremity prosthesis user population. This study aimed to assess the accuracy and reliability of an inertial measurement unit (IMU) system compared to an optical motion capture (OMC) system in transtibial prosthesis (TTP) users. Methods: Thirty TTP users were recruited and underwent simultaneous motion capture from IMU and OMC systems during walking. Reliability and validity were assessed using intra- and inter-subject variability with standard deviation (S.D.), average S.D., and intraclass correlation coefficient (ICC). Results: The intra-subject S.D. for all rotations of the lower limb joints were less than 1° for both systems. The IMU system had a lower mean S.D. (o), as seen in inter-subject variability. The ICC revealed good to excellent agreement between the two systems for all sagittal kinematic parameters. Conclusion: All joint angular kinematic comparisons supported the IMU system’s results as comparable to OMC. The IMU was capable of precise sagittal plane motion data and demonstrated validity and reliability to OMC. These findings evidence that when compared to OMC, an IMU system may serve well in evaluating the gait of lower limb prosthesis users