Conference Paper

A Sensor to Acquire the Relative Movement between Residual Limb and Prosthetic Socket

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

This paper introduces a new approach to measuring relative movement between the residual limb and fitted prosthetic socket in an amputee during gait. Considering requirements motivated by the specific measurement task, a system for the recognition of residual limb movement within the socket system in dynamic gait situations is designed. To evaluate the feasibility of the measurement task with this sensor concept based on an optical 2D-motion sensor, a standalone functional model is established. The functional model is introduced regarding hardware and software components. This paper further presents preliminary experimental evaluation of the functional model. Results considering precision and accuracy of the functional model are displayed. Dependencies to movement velocity, overcome distance, and traveling direction are assessed. Depending on the parameters mentioned above, the realized prototype of the sensor concept shows relative errors regarding accuracy within the range of 2 to 6 %. Precision depends on movement direction as well as path lengths. Overall, the proposed sensor concept seems suitable for acquiring the relative movement between residual limb and prosthetic socket during amputee gait.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... For different reasons, e.g., limitations to statics or altering of interface dynamics, these techniques have severe drawbacks. Thus, a novel measuring approach based on an optical 2D-motion sensor is proposed in [29]. Similar sensor types, which are mainly used in computer mice, have been described as suitable low-cost options for different measuring tasks [30][31][32][33][34][35][36][37]. ...
... This section describes the sensor system used to experimentally evaluate the applicability of the 2D-motion sensor for the described measurement task. The measuring concept itself has been proposed in [29], which gives a more detailed description of the electronic and software implementation. ...
... Evaluation Points n x ± σx in mm n Outside δspr Max(err rel ) Even though slightly underestimating the relative movements, the sensor functionality on a convex surface is satisfactory. With absolute errors err ab ≤ 1 mm, the sensor fulfills the requirements set in [29]. ...
Article
Full-text available
A sensor system for measuring the relative movement between prosthetic socket and residual limb based on a 2D-motion sensor is introduced and thoroughly tested experimentally. The quantitative analysis of test rig evaluation is used to identify advantageous sensor settings and liner configurations. Considering these favorable settings, sensor functionality is quantified to errrel=0.52±1.78%. Advancing to convex measurement surfaces, the sensor shows absolute errors of errabs≤1 mm in an observable measurement scenario. The feasibility of measuring gait-induced relative movement with the proposed 2D-motion sensor is shown via a biomechanical plausibility study. Overall, the findings suggest that the proposed sensor system is suitable for investigating the relative movement between residual limb and prosthetic socket in dynamic gait situations.
... A concept for measuring the relative motion between residual limb surface and prosthetic socket at specific locations in dynamic gait situations is presented in [15]. The proposed concept is based on optical 2D-motion sensor units, whose applicability has been tested experimentally using a functional model consisting of one sensor unit on a test rig as well as in biomechanical substitute studies [16]. ...
Article
Full-text available
The relative motion between residual limb and prosthetic socket could be a relevant factor in quantifying socket fit. The measurement of these movements, particularly in dynamic gait situations, poses a challenging task. This paper presents the realization of a measurement concept based on multiple optical 2D-motion sensors. The performance of the system was evaluated on a test rig considering accuracy and precision as well as accomplished measurement frequency and reliability of the system. Additionally, results of a pilot study measuring the relative motion between residual limb and prosthetic socket at seven specific locations of one individual with transtibial amputation during straight level walking are presented. The sensor functionality of the array was confirmed and the test rig experiments were comparable to the previously tested functional model ( e r r rel = 0.52 ± 1.87 %). With a sampling frequency of 1.3 kHz to be distributed among the number of sensor units, the developed system is suitable for investigating the relative movement between residual limb and prosthetic socket in dynamic gait situations. Results of the pilot study show the majority of relative motion occurring during the second half of the gait cycle. The measured relative motions show the residual limb sinking deeper into the socket, extending in the Sagittal plane and rotating internally in the Transverse plane during stance phase. Data captured during swing phase indicate a lower limb extension in the Sagittal plane as well as an external rotation in the Transverse plane.
... The interaction between the prosthetic socket and the stump skin is dominated by the deformation of the skin tissue, but there also exists a small amount of relative slip. Researchers have designed specific sensors to measure the relative slip of the interface between the prosthetic socket and the stump [20]. Hence, a reciprocating friction experiment between the bionic surface of the prosthetic socket and the human skin can be conducted to simulate the interface interaction between the prosthetic socket and the stump skin, and to evaluate the performance of the bionic surfaces based on the reciprocating friction characteristics. ...
Article
Full-text available
In this study, three types of bionic texture surfaces were designed, based on the microstructure of tree frog and gecko feet, for two typical prosthetic substrates: silicone rubber and thermoplastic polyurethane elastomer (TPU). The surface energy of all bionic texture surfaces, and the relative displacement and energy dissipation of the reciprocating friction between these bionic surfaces and skin, were investigated. The results revealed that the bionic texture of the prosthetic socket surface had an obvious influence on the surface characteristics and reciprocating characteristics of friction with the skin. According to the comprehensive weight rating method, the optimal bionic textures for the silicone rubber substrate were a regular hexagonal prism and a quadrangular prism; for the TPU substrate, only the regular quadrangular prism texture was optimal. These textures can effectively increase the surface energy of the surface of the prosthetic socket, thereby increasing its adhesion to skin and reducing the dissipation of friction energy when it interacts with the stump. This bionic prosthetic socket surface design helps improve the adaptation between the prosthetic socket and the stump.
Conference Paper
Full-text available
This paper introduces a novel measuring approach for detecting relative movement between stump and socket in lower limb prostheses. The application of the motion capturing based measuring approach is shown at a single male transtibial amputee using a Patella Tendon Bearing (PTB) socket. It further investigates and assesses the feasibility of measuring the relative movement between stump and socket during level walking at different velocities and allocating it to the coinciding loads. Representative results for the two translational degrees of freedom in the sagittal plane are presented and discussed. For the proximodistal (pd) direction, a linear correlation between applied load and relative movement is found, while for the anteroposterior (ap) direction the stump movement is largely influenced by the motion sequence during the respective gait event. Additionally, the effect of walking speed is discussed.
Article
Full-text available
Background Today a number of prosthetic suspension systems are available for transtibial amputees. Consideration of an appropriate suspension system can ensure that amputee’s functional needs are satisfied. The higher the insight to suspension systems, the easier would be the selection for prosthetists. This review attempted to find scientific evidence pertaining to various transtibial suspension systems to provide selection criteria for clinicians. Methods Databases of Pub Med, Web of science, and science Direct were explored to find related articles. Search terms were as follows: “Transtibial Prosthesis (32), prosthetic suspension (48), lower limb prosthesis (54), below-knee prosthesis (58), prosthetic liner (20), transtibial (193), and prosthetic socket (111). Two reviewers separately examined the papers. Study design (case series of five or more subjects, retrospective or prospective), research instrument, sampling method, outcome measures and protocols were reviewed. Findings Based on the selection criteria, 22 articles (15 prospective studies, and 7 Surveys) remained. Sweat control was found to be a major concern with the available suspension liners. Donning and doffing procedures for soft liners are also problematic for some users, particularly those with upper limb weakness. Moreover, the TSB socket with pin/lock system is favored by the majority of amputees. Interpretation In summary, no clinical evidence is available to suggest what kind of suspension system could have influential effect as a "standard" system for all transtibial amputees. However, among various suspension systems for transtibial amputees, the Iceross system was favored by the majority of users in terms of function and comfort.
Article
Full-text available
This paper presents a new 3D design paradigm for the development of specific custom-fit products, such as the soft socket of prostheses for lower limb amputees. It is centered on the digital model of the human body and, contrarily to the traditional process almost manually based, it considers the integration of methods and tools coming from different research and application fields: Reverse Engineering, Medical Imaging, Virtual Prototyping, Physics-based Simulation, and Rapid Prototyping. The paper describes the techniques adopted to acquire and create the digital model of the residual limb, the procedure to generate the socket model, the strategy developed for the functional simulation of the socket-stump interaction and, finally, the realization of the physical prototype. Each design step is described with the related problems and the obtained results. Both trans-tibial and trans-femoral amputees have been considered; however, for now the complete process has been validated for trans-tibial prostheses. Major outcomes of the proposed approach stand in a better quality of the final product, in a shorter involvement of the amputee implying a lower psychological impact, in a limited use of physical prototypes, and in a shorter development time. Moreover, the resulting paradigm answers to the Collaborative Engineering guidelines by optimizing the interaction between different domains and enhancing their contributions in a homogeneous development framework.
Article
Full-text available
Although normal pressures at the stump socket interface of the lower-limb amputee have been investigated, little is known about the shear stresses that also occur. Studies suggest that the combination of both shear and normal stresses significantly exacerbates discomfort and vascular and tissue damage. A means of simultaneously measuring normal and shear stresses will aid in the investigation and improvement of prosthetic fit. A miniature triaxial force transducer (4.9 x 16 mm diameter) has been developed which can be recessed into the socket wall. The principle of operation, construction, performance and limitations of the device are described. Preliminary measurements of the interface stress variations over the gait cycle in a supra-condylar PTB socket are presented. These show clear differences in the stress patterns present when two different prosthetic feet are used.
Article
Full-text available
This study analyses the motion of the residual femur within a transfemoral socket during gait using ultrasound data from two simultaneously transmitting transducers connected to two ultrasound scanners. Calibration tests accurately established the orientation of the two transducers mounted on the lateral wall of the socket. Relative positions of the ultrasound image of the femur were measured on video playback. Motion of the residual femur, relative to the lateral wall of the socket, at any instant during gait may be estimated, if the relative positions of the two transducers and the motion of the ultrasound image are known. A consistent pattern of femoral motion during 10 gait cycles is displayed graphically. The femoral motion in this paper is expressed as abduction/adduction or flexion/extension relative to the socket. However, without a full gait analysis study, the orientation of the socket relative to the ground or relative to the pelvis cannot be determined. Only one ultrasound scanner may be available for clinical use. Hence data collection may be restricted to only one transducer during gait. In order to simulate the single transducer mode, the ultrasound data recorded during the 10 previous gait cycles, was averaged at any instant of the gait cycle. The angular orientation of the femur was calculated based on the averaged data. Similar patterns of femoral motion were obtained irrespective of the technique adopted.
Article
Full-text available
Scientific studies have been conducted to quantify attributes that may be important in the creation of more functional and comfortable lower-limb prostheses. The prosthesis socket, a human-machine interface, has to be designed properly to achieve satisfactory load transmission, stability, and efficient control for mobility. The biomechanical understanding of the interaction between prosthetic socket and the residual limb is fundamental to such goals. The purpose of this paper is to review the recent research literature on socket biomechanics, including socket pressure measurement, friction-related phenomena and associated properties, computational modeling, and limb tissue responses to external mechanical loads and other physical conditions at the interface. There is no doubt that improved biomechanical understanding has advanced the science of socket fitting. However, the most recent advances in the understanding of stresses experienced at the residual limb have not yet led to enough clinical consensus that could fundamentally alter clinical practice. Efforts should be made to systematically identify the major discrepancies. Further research should be directed to address the critical controversies and the associated technical challenges. Developments should be guided to offer clinicians the quantification and visualization of the interaction between the residual limb and the prosthetic socket. An understanding of comfort and optimal load transfer as patterns of socket interface stress could culminate in socket design expert systems.
Article
Full-text available
This study analyses the residual femur motion of a single amputee within a trans-femoral socket during a series of daily living activities. Two simultaneously transmitting, socket mounted transducers were connected to two ultrasound scanners. Displacement measurements of the ultrasound image of the femur were video recorded and measured on “paused” playback. Abduction/adduction and flexion/extension of the residual femur within the socket at any instant during these activities were estimated, knowing the relative positions of the two transducers and the position of the residual femur on the ultrasound image. Consistent motion patterns of the residual femur within the trans-femoral socket were noted throughout each monitored daily living activity of the single amputee studied. Convery and Murray (2000) reported that during level walking, relative to the socket, the residual femur extends 6° and abducts 9° by mid-stance while flexing 6° and adducting 2° by toe-off. Uphill/downhill, turning to the right and stepping up/down altered this reported pattern of femoral motion by approximately 1°. During the standing activity from a seated position the femur initially flexed 4° before moving to 7° extension, while simultaneously adducting 6°. During the sitting activity from a standing position the femur moved from 7° extension and 6° adduction to 3° flexion and 1° abduction. The activity of single prosthetic support to double support introduced only minor femoral motion whereas during the activity of prosthetic suspension the femur flexed 8° while simultaneously adducting 9°. Additional studies of more amputees are required to validate the motion patterns presented in this investigation.
Article
Full-text available
Daily volume loss of the stump leads to a poor fit of the prosthetic socket. A method of preventing this volume loss and maintaining a good fit was developed. A vacuum (-78 kPa) was drawn on the expulsion port of a total surface-bearing suction socket to hold the liner tightly against the socket. Stump volume of 10 trans-tibial amputees was measured prior to and immediately after a 30 minute walk with normal and vacuum socket conditions. Under the normal condition, the limb lost an average of 6.5% of its volume during the walk. In contrast, with the liner held tightly by vacuum, the limb gained an average of 3.7% in volume. It is believed that the difference observed between conditions resulted from a greater negative pressure developed during the swing phase of gait with the vacuum condition. X-rays revealed that the limb and tibia pistoned 4 mm and 7 mm less, respectively, under the vacuum condition. The combination of reduced pistoning and maintenance of volume is thought to account for the more symmetrical gait observed with the vacuum.
Article
Full-text available
Individuals with unilateral trans-femoral amputations due to non-vascular causes were studied in a mailed survey designed to investigate health-related quality of life (HRQL), prosthetic use and problems. The Swedish SF-36 Health Survey and a structured questionnaire designed for trans-femoral amputees were used. The series consisted of 97 subjects (60 men, 37 women), aged 20 to 69 years with a mean of 22 years since the amputation. Trauma was the cause of amputation in 55%, tumour in 35% and other causes in 10%. Ninety-two (92) subjects (95%) had a prosthesis and 80 (82%) used it daily. General HRQL was significantly lower than Swedish age- and gender-matched norms in all dimensions as measured by SF-36. Most frequently reported problems that had led to reduction in quality of life were heat/sweating in the prosthetic socket (72%), sores/skin irritation from the socket (62%), inability to walk in woods and fields (61%) and inability to walk quickly (59%). Close to half were troubled by stump pain (51%), phantom limb pain (48%), back pain (47%) and pain in the other leg (46%). One fourth considered themselves to have a poor or extremely poor overall situation. Transfemoral amputation, due to non-vascular causes, has an evident impact on quality of life and there are considerable problems related to the amputation and the prosthesis. Efforts to improve the physical and the psychological well-being for this group, with a long life expectancy, are needed.
Article
Full-text available
Present models in the literature, predicting that prostheses should not be too lightweight, are not supported by empirical evidence. Recent studies suggest that these models are incorrectly based on the assumption that the swing phase is uninfluenced by muscle activity. The purpose of the present study was to introduce a new mathematical model to predict the effect of mass properties on the gait of transtibial amputees, based on experimental findings that subjects adapt to mass perturbations by maintaining the same joint kinematics. Effect of mass perturbations on the lower leg was evaluated in terms of muscular cost and forces between stump and socket, using a linked-segment model of the swing phase. Gait analysis and anthropometric data from 10 transtibial amputees were used as model input. Location of perturbation strongly influenced the muscular cost. Cost generally increased after distally adding mass but decreased after proximally adding mass to the lower leg. Stump-socket interface forces always increased after mass addition. A new model was introduced, predicting that the weight of distally located components (e.g. foot, ankle, shoe) strongly influence the estimated muscular cost, in contrast to proximal components. A comparison with experimental literature suggests this new model better describes the experimental data than existing models.
Article
Design and fitting of artificial limbs to lower limb amputees are largely based on the subjective judgement of the prosthetist. Understanding the science of three-dimensional (3D) dynamic coupling at the residuum/socket interface could potentially aid the design and fitting of the socket. A new method has been developed to characterise the 3D dynamic coupling at the residuum/socket interface using 3D motion capture based on a single case study of a trans-femoral amputee. The new model incorporated a Virtual Residuum Segment (VRS) and a Socket Segment (SS) which combined to form the residuum/socket interface. Angular and axial couplings between the two segments were subsequently determined. Results indicated a non-rigid angular coupling in excess of 10° in the quasi-sagittal plane and an axial coupling of between 21-35 mm. The corresponding angular couplings of less than 4° and 2° were estimated in the quasi-coronal and quasi-transverse plane, respectively. We propose that the combined experimental and analytical approach adopted in this case study could aid the iterative socket fitting process and could potentially lead to a new socket design.
Conference Paper
This paper presents a new direct measurement system which enable an amputee gait assessment independent of location, not restricted in ground conditions or tasks. As an adapter it is implemented in the structure of the lower limb prosthesis to measure load and motions in six degrees of freedom. A pilot study of typical tasks for gait analysis applying the integrated measurement system is shown. The resulting measured parameter of the system demonstrates reasonable data compared to reference data of able-bodied humans.
Article
Management of residual limb volume affects decisions regarding timing of fit of the first prosthesis, when a new prosthetic socket is needed, design of a prosthetic socket, and prescription of accommodation strategies for daily volume fluctuations. This systematic review assesses what is known about measurement and management of residual limb volume change in persons with lower-limb amputation. Publications that met inclusion criteria were grouped into three categories: group I: descriptions of residual limb volume measurement techniques; group II: studies investigating the effect of residual limb volume change on clinical care in people with lower-limb amputation; and group III: studies of residual limb volume management techniques or descriptions of techniques for accommodating or controlling residual limb volume. We found that many techniques for the measurement of residual limb volume have been described but clinical use is limited largely because current techniques lack adequate resolution and in-socket measurement capability. Overall, limited evidence exists regarding the management of residual limb volume, and the evidence available focuses primarily on adults with transtibial amputation in the early postoperative phase. While we can draw some insights from the available research about residual limb volume measurement and management, further research is required.
Article
The PTB-suction prosthesis has been studied by a roentgenological technique. There is complete contact between the skin of the stump and the plastic inner surface of the socket. The movement of the stump in the socket is minimal. The displacement of the skeletal stump is reduced to half in the PTB-suction prosthesis, compared with the strap-suspended PTB prosthesis. As a result, the stability between stump and socket is increased, provided that the stump is sufficiently long. Skin sores are avoided. The prosthesis, when adequately fitted, guarantees a good circulation within the stump and a cosmetically favourable fit with a feeling of walking with "a normal leg".
Article
To investigate the movement of the tibial end in the sagittal plane in the PTB prosthetic socket during a gait cycle, 7 patients with a median age of 72 years were examined using X-ray technique. The gait cycle was reduced to four different static positions: heel contact, midstance, push-off and swing phase. The mean value of tibial movement in the socket in the anteroposterior direction was 2.2 cm, in proximodistal direction 2.8 cm, and the total sagittal movement during the whole gait cycle was 7.5 cm. The results indicate that one factor affecting the magnitude of the movement was the prestretching of soft tissues. All the patients who experienced a good prosthetic fitting had their soft tissues prestretched. The extreme dorsal and proximal positions of the tibial end during the gait cycle was in the swing phase position. The extreme distal position occurred somewhere between mid-stance and push-off. The extreme anterior position of the tibial end was seen during heel contact. This study has shown the magnitude of the movements in a PTB socket during a simulated gait cycle. The study has given hints on factors affecting prosthetic fitting, and further research within this field might provide indications of how to optimise socket shape to give maximal patient comfort.
Article
The ability to measure skin surface slippage relative to the internal wall of a lower extremity prosthesis under various loading conditions is important for evaluation of socket fit and function, and creation of finite element models. Skin surface three-dimensional (3D) shape measurements with tracking of fiducial displacements in situ under axial loading of the prosthesis have not previously been reported. Analysis of slippage within the prosthesis has been performed using a new experimental measurement method based on spiral x-ray computed tomography (SXCT) imaging. Small lead markers were placed on the residuum of an adult with a below-knee amputation, and SXCT scans were obtained with the prosthesis in situ under two static axial loading conditions (44.5N and 178N). The 3D scan data were used to assess slippage with three methods: gross displacement of the tibia and distal end of the residuum; relative displacement of markers; and distance measurements between markers. The markers affixed to the below-knee skin surface within the prosthesis were measured. The skin slipped from 2 to 6 mm relative to the internal prosthesis wall when an additional load of 133.5N was applied in the axial direction to the distal end of the prosthesis. The tibial remnant moved 10.0 mm distally relative to the prosthesis internal wall. This method provides a feasible means for measuring residuum skin slippage relative to the prosthesis and skin deformation relative to tibia within an in situ prosthesis under load.
Article
X-ray and cineradiography measurements were used to compare the suspension effect and stability of a TSB trans-tibial prosthesis with an Icelandic Roll-On Silicone Socket (ICEROSS) system to that of a PTB trans-tibial prosthesis. The suspension effect was measured by the distance between the tibia and the socket in both suspension position and weight-bearing position in both type of prostheses. The suspension effect of the TSB prosthesis (2.53 +/- 0.90 cm) was superior to that of the PTB prosthesis (3.60 +/- 0.56 cm) (p < 0.05) by x-ray measurement. The suspension effect of the TSB prosthesis (0.1, 0.4, 0.72 cm) was superior to that of the PTB prosthesis (0.3, 0.48, 1.03 cm) (p < 0.01, p < 0.05) by cineradiographic measurement. The stability was measured as the angle between the axis of the tibia and the prosthesis at the time of heel contact and toe off. The angle change of the TSB prosthesis was statistically smaller than that of the PTB prosthesis.
Article
A system for measuring pressures and bi-axial shear stresses at the body support interfaces has been developed. This system has been used, in five unilateral trans-tibial amputees, to investigate the stresses at multiple points on the residual limb and prosthetic socket interface during standing and walking. The subjects investigated regularly used a patellar-tendon-bearing socket. The maximum peak pressure at the measured points was 320 kPa over the popliteal area during walking. The maximum shear stress was 61 kPa over the medial tibia area. Variable wave-forms of stress during walking were observed at the different measured points. The influence of the angular alignment on the stresses was investigated on one subject. It was found that a miss-alignment of +/- 8 degrees produced a change in peak longitudinal shear stress of between 8% and 11.5%.
Article
This article traces the development of microprocessor prosthetic knees from early research in the 1970s to the present. Read about how microprocessor knees work, functional options, patient selection, and the future of this prosthetic.
Einfiuss des c-leg-kniegelenk-passteiles der fa. otto bock auf die versorgungsqualität oberschenke-lamputierter
  • U Hafkemeyer
  • B Drerup
Appreciation of prosthetic socket fitting from basic engineering principles. National Centre for Training and Education in Prosthetics and Orthotics Glasgow
  • B Klasson
B. Klasson, Appreciation of prosthetic socket fitting from basic engineering principles. National Centre for Training and Education in Prosthetics and Orthotics Glasgow, 1995.
ADNS-9800: Laser Gaming Sensor
Pixart Imaging Inc., "ADNS-9800: Laser Gaming Sensor," uRL: http://www.pixart.com.tw/upload/ADNS-9800%20DS S V1.0 20130514144352.pdf. Cecked: 09.06.2015. -Data Sheet.