Adjustable prosthetic sockets: a systematic review of industrial and research design characteristics and their justifications.

BACKGROUND: The prosthetic socket is a key component that influences prosthesis satisfaction, with a poorly fitting prosthetic socket linked to prosthesis abandonment and reduced community participation. This paper reviews adjustable socket designs, as they have the potential to improve prosthetic fit and comfort through accommodating residual limb volume fluctuations and alleviating undue socket pressure. METHODS: Systematic literature and patent searches were conducted across multiple databases to identify articles and patents that discussed adjustable prosthetic sockets. The patents were used to find companies, organisations, and institutions who currently sell adjustable sockets or who are developing devices. RESULTS: 50 literature articles and 63 patents were identified for inclusion, representing 35 different designs used in literature and 16 commercially available products. Adjustable sockets are becoming more prevalent with 73% of publications (literature, patents, and news) occurring within the last ten years. Two key design characteristics were identified: principle of adjustability (inflatable bladders, moveable panels, circumferential adjustment, variable length), and surface form (conformable, rigid multi-DOF, and rigid single DOF). Inflatable bladders contributed to 40% of literature used designs with only one identified commercially available design (n = 16) using this approach. Whereas circumferential adjustment designs covered 75% of identified industry designs compared to only 36% of literature devices. Clinical studies were generally small in size and only 17.6% of them assessed a commercially available socket. DISCUSSION: There are clear differences in the design focus taken by industry and researchers, with justification for choice of design and range of adjustment often being unclear. Whilst comfort is often reported as improved with an adjustable socket, the rationale behind this is not often discussed, and small study sizes reduce the outcome viability. Many adjustable sockets lack appropriate safety features to limit over or under tightening, which may present a risk of tissue damage or provide inadequate coupling, affecting function and satisfaction. Furthermore, the relationship between design and comfort or function are rarely investigated and remain a significant gap in the literature. Finally, this review highlights the need for improved collaboration between academia and industry, with a strong disconnect observed between commercial devices and published research studies.

Exploring The Future of Prosthetics and Orthotics: Harnessing The Potential of 3D Printing.

This paper explores the transformative impact of 3D printing on Orthotics and Prosthetics, focusing on enhancing patient outcomes and clinical efficiency. Over the past decade, the integration of additive manufacturing has revolutionized device fabrication, particularly in diagnostic socket production, leading to significant time reductions in patient care. This article addresses challenges such as material limitations and the need for equivalent strength to traditional sockets, exploring the use of PETG filaments and advanced printers. It emphasizes the role of digital scanning and model modification technology, highlighting affordable solutions like Structure Sensor Scanners and iPhone-based capture systems in shaping the digital workflow. The importance of a standardized digital workflow in clinical settings is discussed, showcasing reduced practitioner time and improved patient care. The paper concludes by outlining ongoing efforts to enhance patient care through automation and flexible prints. In summary, this paper provides a concise overview of the impactful advancements in Orthotics and Prosthetics through 3D printing, highlighting its potential for improved clinical efficiency and patient outcomes.

Digital Workflow for Implant Placement and Immediate Chairside Provisionalization of a Novel Implant System without Abutment-A Case Report.

Dental implants have been placed millions of times worldwide, and the surgical procedure and implant design have steadily improved. The basic prosthetic connection, which makes use of an abutment, has changed little over the past decades. These days, implant placement with immediate provisionalization is an essential stage in implant dentistry and interdisciplinary treatment strategies. Temporary computer-aided design and computer-aided manufacturing (CAD/CAM) of implant-supported crowns restore esthetics and guarantee function during the restoration process and the osseointegration of the dental implant. This case report describes the digital planning; the immediate, static, computer-assisted implant surgery, and the immediate chairside provisionalization of a novel implant system that is directly screw-retained without an abutment.

The effect of the transfemoral prosthetic socket interface designs on skeletal motion and socket comfort: A randomized clinical trial.

BACKGROUND: The most crucial aspect of a prosthesis is the socket, as it will directly determine gait stability and quality. The current standard of care ischial ramus containment socket is reported to increase coronal stability through gait; however, socket discomfort is the primary complaint among prosthetic users. OBJECTIVES: The purpose of this study is to compare ischial ramus containment to alternatives in the transfemoral amputee population. All subjects were fit with three different sockets: traditional ischial ramus containment, a dynamic socket, and a sub-ischial. In this study, authors hypothesized socket skeletal motion would be equivalent across interventions. STUDY DESIGN: Single-blind, repeated-measures, three-period randomized crossover clinical trial. METHODS: Outcome measures were socket comfort score and skeletal motion, viewed coronally with X-ray measuring the position of the skeleton in relationship to the socket in full weight-bearing and full un-loading. RESULTS: The mean age was 38.2 and mean Amputee Mobility Predictor score was 40. Mean vertical movement, horizontal movement, single limb prosthetic stance, mean femoral adduction in swing and stance, and median socket comfort score were not statistically different. CONCLUSION: The socket design did not significantly effect skeletal motion and socket comfort. All socket designs are suitable depending on the patient-centric preferences and prosthetist skill set. CLINICAL RELEVANCE: The comfort of the standard of care transfemoral amputation socket has been widely reported as problematic. A comparison of alternative designs in a controlled clinical trial environment will assist the clinician in understanding the impact of design regarding skeletal motion and comfort. Users could benefit from alternatives applied in clinical practice.

Stakeholder perspectives for possible residual limb monitoring system for persons with lower-limb amputation.

Purpose: To gather ideas from lower-limb prosthesis users and certified prosthetists regarding possible residual limb monitoring system features and data presentation. We also gathered information on the type of residual limb problems typically encountered, how they currently manage those problems, and their ideas for methods to better manage them.Materials and methods: Two focus groups were held; one with certified prosthetists and another with lower-limb prosthesis users. Open-ended questions were used in a moderated discussion that was audio recorded, transcribed, and assessed using applied thematic analysis.Results and conclusions: Seven individuals participated in each focus group. Prosthetists came from a mix of practice settings, while prosthesis users were diverse in level of amputation, aetiology, and years of experience using lower-limb prostheses. Residual limb problems reported by participants were consistent with those in the literature. Participants suggested better managing residual limb problems through improved education, better detection of residual limb problems, and using sensor-based information to improve prosthetic technology. Participants favoured short-term use of a possible residual limb monitoring systems to troubleshoot residual limb problems, with temperature and pressure the most frequently mentioned measurements. Participants described that an ideal residual limb monitoring system would be lightweight, not interfere with prosthesis function, and result in benefits with regard to prosthetic care and socket function that outweighed inconveniences or concerns regarding system use. A potential positive of system use included having objective data for reimbursement justification, although it was pointed out that the residual limb monitoring system itself also needed to be reimbursable.Implications for RehabilitationStakeholders suggested better managing residual limb problems through improved education, better detection of residual limb problems, and using sensor-based information to improve prosthetic technology.Stakeholders favored short-term use of a possible system to troubleshoot residual limb problems, with temperature and pressure the most frequently mentioned measurements.Stakeholders described that an ideal residual limb monitoring system would be lightweight, not interfere with prosthesis function, and result in benefits with regard to prosthetic care and socket function that outweighs any inconveniences or concerns regarding system use.Stakeholders indicated that a potential positive of system use included having objective data for reimbursement justification, although it was pointed out that the residual limb monitoring system itself also needed to be reimbursable.

Changes in periprosthetic bone mineral density and bone turnover markers after osseointegrated implant surgery: A cohort study of 20 transfemoral amputees with 30-month follow-up.

BACKGROUND: The osseointegrated implant system is a treatment option for people with transfemoral amputation, but implant removal is not uncommon. The association between bone mineral density changes or bone turnover markers and the need for implant removal has not previously been investigated. OBJECTIVES: The aim was to evaluate changes in bone mineral density and bone turnover markers in people with transfemoral amputations treated with osseointegrated implants. STUDY DESIGN: This is a prospective cohort study. METHODS: Nineteen patients were followed up for 30 months or until implant removal. Bone mineral density was measured in the lumbar spine, proximal femur and seven periprosthetic regions. 25-hydroxyvitamin (D2 + D3), parathyroid hormone, N-terminal propeptide of type-I procollagen, C-telopeptide of type-I collagen, bone-specific alkaline phosphatase and osteocalcin were measured in blood samples. RESULTS: Four fixtures and three abutments were removed. Patients with removed implants had a decreased bone mineral density in the seven periprosthetic regions between 27% (95% confidence interval = 6; 43) and 38% (95% confidence interval = 19; 52) at 30-month follow-up compared to baseline (p < 0.02), whereas bone mineral density around non-removed implants normalized to baseline values (p > 0.08). C-telopeptide of type-I collagen was significantly different between the groups at 18- and 24-month follow-up (p < 0.05). None of the measured variables were significant predictors of implant removal (p > 0.07). CONCLUSION: Implant removal was associated with loss of periprosthetic bone mineral density and increase in C-telopeptide of type-I collagen in the years following osseointegrated surgery. CLINICAL RELEVANCE: This study offers new insight into changes in bone mineral density and bone turnover markers that precipitate aseptic or septic osseointegrated implant removal. Results of this study could contribute to clinical guidelines for monitoring rehabilitation progress and implant removal through dual-energy X-ray absorptiometry or surrogate markers like C-telopeptide of type-I collagen.

How do transtibial residual limbs adjust to intermittent incremental socket volume changes?

BACKGROUND: Strategies to maintain prosthesis users' daily limb volume are needed. OBJECTIVES: Test how intermittent incremental socket volume adjustments affect limb fluid volume and limb-socket distance. STUDY DESIGN: Repeated measures. METHODS: People with transtibial limb loss walked on an outdoor trail wearing a motor-driven adjustable socket that they adjusted a small amount, approximately 0.3% socket volume, every 2 min using a mobile phone app. Limb fluid volume and sensed distance between the socket and a target in their elastomeric liner were monitored. A gradual socket enlargement phase was followed by a gradual socket reduction phase. RESULTS: An incremental socket enlargement significantly increased limb fluid volume (p < 0.001) but not sensed distance (p = 0.063). An incremental socket reduction significantly decreased both limb fluid volume (p < 0.001) and sensed distance (p < 0.001). CONCLUSION: Participants' residual limb fluid volume increases during ambulation compensated for incremental socket volume increases. For incremental socket volume decreases, residual limb fluid volume decreases did not compensate and the socket fit became tighter. CLINICAL RELEVANCE: Results support the hypothesis that for people without co-morbidities, intermittent incremental socket volume enlargements are an effective accommodation strategy to increase limb fluid volume while maintaining socket fit. Intermittent incremental socket volume reductions decreased limb fluid volume but also made the socket fit tighter.

An adaptive socket with auto-adjusting air bladders for interfacing transhumeral prosthesis: A pilot study.

Comfort is a critical aspect in the application of wearable device, such as rehabilitation robots and upper limb prostheses. As a physical interface between human body and prosthetic limb, the socket and its comfort largely contribute to the user's acceptance. Traditional sockets are static, lacking dynamic adjustment mechanism for the contact pressure. To ensure a reliable suspension during daily activities, the socket is usually designed to be tightly attached, with a large stress, on the residual limb, which may introduce considerable discomfort during long-term use. In this article, we present a novel adaptive transhumeral socket, in which we employ four independent bladders contacting with the stump. Not only can these bladders provide a necessary suspension for the device but also form an air cushion (soft body) that helps relieve the pressure concentration between the biological body and physical prosthesis. In real time, this adaptive socket continuously monitors the limb posture, the operating load, and the contacting pressure between the socket and the limb, and then dynamically adjusts the clamping force to ensure a reliable attachment during various daily activities. Since well adapting to the contours of the stump, the bladders can effectively accommodate the volume change of the stump, making a balanced load distribution on load-tolerant areas. Through modeling and numerical analysis, we established a dynamic strategy for estimating the external load and an automatic scheme for adjusting the bladders' air pressure. Finally, a close-loop control was constructed based on the contact pressure measured by our self-developed force sensors. Our preliminary experiments on one normal (i.e. non-amputee) subject verified the effectiveness of the proposed method, showing that the adaptive socket can considerably reduce the socket-limb contact pressure while sustaining a secure suspension on the upper arm.

Adjustable sockets may improve residual limb fluid volume retention in transtibial prosthesis users.

BACKGROUND: Loss of residual limb volume degrades socket fit and may require accommodation. OBJECTIVES: To examine if either of two accommodation strategies executed during resting, socket release with full socket size return and socket release with partial socket size return, enhanced limb fluid volume retention during subsequent activity. STUDY DESIGN: Two repeated-measures experiments were conducted to assess the effects of socket release on limb fluid volume retention. METHODS: Limb fluid volume was monitored while participants wore a socket with a single adjustable panel. Participants performed eight activity cycles that each included 10 min of sitting and 2 min of walking. The socket's posterior panel and pin lock were released during the fifth cycle while participants were sitting. In one experiment (Full Return), the socket was returned to its pre-release size; in a second experiment (Partial Return), it was returned to 102% of its pre-release size. Short-term and long-term limb fluid volume retention were calculated and compared to a projected, No Intervention condition. RESULTS: Partial Return and Full Return short-term retentions and Partial Return long-term retention were greater than those projected under the control condition ( p < 0.05). CONCLUSION: Socket release during resting after activity, particularly when the socket is returned to a slightly larger size, may be an effective accommodation strategy to reduce fluid volume loss in transtibial prosthesis users. CLINICAL RELEVANCE: This study suggests that existing prosthetic technologies' adjustable sockets and locking pin tethers can be used in novel ways to help maintain residual limb fluid volume in active prosthesis users.

Effects of activity intensity, time, and intermittent doffing on daily limb fluid volume change in people with transtibial amputation.

BACKGROUND:: The volume of a prosthesis user's residual limb changes during the day and may affect the fit of the prosthesis. These changes must be managed by the user to prevent discomfort, skin breakdown, and falls. OBJECTIVES:: The objectives were to test how activity, time of day, and intermittent doffing affected residual limb fluid volume in people with transtibial amputation. STUDY DESIGN:: Standardized, repeated measure (A-B-A) out-of-laboratory protocol. METHODS:: Participants with transtibial amputation completed three 6-h test sessions. Two sessions served as controls (A protocol) during which participants left their prosthesis donned, and one session was an intervention (B protocol) where participants doffed their prosthesis twice for 20 min during the 6 h of testing. Within-socket fluid volume was measured using a custom portable bioimpedance analysis system. RESULTS:: A total of 13 participants completed the study. The rate of limb fluid volume loss was higher early in the session compared with late in the session. Participants experienced less fluid volume loss during high activity than low activity. Socket users with pin suspension experienced less posterior fluid volume loss when they intermittently doffed their prosthesis. Intermittent doffing did not benefit limb fluid volume of mechanical vacuum and suction suspension users. CONCLUSION:: High activity may reduce fluid volume loss compared with low activity. Intermittent doffing may provide volume accommodation for transtibial prosthesis users with pin suspension. CLINICAL RELEVANCE: Prosthetists should query their patients about the intensity of activity they conduct when advising them on limb volume management. Patients using sockets with pin suspension may be able to offset limb fluid volume loss by periodically doffing the prosthesis.

UK trial of the Osseointegrated Prosthesis for the Rehabilitation for Amputees: 1995-2018.

BACKGROUND:: Amputation of a limb impacts on patients' self-perception and quality of life. Prostheses directly anchored to the skeleton are being investigated, aiming to avoid soft tissue complications. OBJECTIVES:: We report outcome data for the UK trial of the Osseointegrated Prosthesis for the Rehabilitation of Amputees Implant System with a minimum of 9-year follow-up. METHODS:: Eighteen transfemoral amputees received unilateral implants between 1997 and 2008. Five were implanted before a formalised protocol, called Osseointegrated Prosthesis for the Rehabilitation of Amputees, was developed. Mean follow-up of the Pre-Osseointegrated Prosthesis for the Rehabilitation of Amputees group is 11.4 years (1.8-18.6 years), while for the Post-Osseointegrated Prosthesis for the Rehabilitation of Amputees group it is 12.3 years (2.9-15.9). RESULTS:: The Kaplan-Meier cumulative survivorship is 40% for the Pre-Osseointegrated Prosthesis for the Rehabilitation of Amputees group and 80.21% for the Post-Osseointegrated Prosthesis for the Rehabilitation of Amputees group. Five implants (28%) have been removed, three (17%) for deep infection, one (5.6%) for chronic pain, later proven to be infected and one (5.6%) due to implant fracture secondary to loosening due to infection. Two patients (11%) have peri-implant infections suppressed with oral antibiotics. Eleven cases (61%) of superficial infection were successfully treated with antibiotics. 36-Item short-form health survey and Questionnaire for persons with a Transfemoral Amputation showed significant improvements in quality of life up to 5 years after implantation. CONCLUSION:: This small cohort of patients demonstrates osseointegrated prosthesis allows prolonged usage and improves patients' quality of life compared to conventional prostheses. CLINICAL RELEVANCE: These prostheses may provide a future gold standard for amputees and this study provides the first outcome data over such a time period to be reported from outside of the developers group.

Attachment of upper arm prostheses with a subcutaneous osseointegrated implant in transhumeral amputees.

BACKGROUND: The stump-socket interface is of utmost importance for prosthetic function in transhumeral amputees. Stability of this connection may be improved using a newly designed subcutaneous implant. OBJECTIVES: The purpose was to determine the effect of the implant together with customized socket designs on the range of motion of the shoulder and the prosthetic function compared to conventional fitting. STUDY DESIGN: Case series. METHODS: The range of motion was measured with scaled metrics and the prosthetic function evaluated with the Southampton Hand Assessment Procedure and the Box and Block Test. Maximal loading was measured in straight and 90° flexion of the elbow. RESULTS: The restriction of range of motion after conventional fitting was decreased from 42.55% ± 6.56% to 9.23% ± 14.89% in Patient I and from 62.18% ± 15.19% to 2.51% ± 2.49% in Patient II using the implant with customized sockets compared to range of motion without prosthesis. Both patients showed improved prosthetic function with the new system compared to conventional fitting. CONCLUSION: The presented subcutaneous humeral implant, together with customized socket designs without straps and harnesses to the contralateral shoulder, can maintain almost complete range of motion of the shoulder. This resulted in improved prosthetic function and comfort for the patient without constant risk of infection. Clinical relevance Discomfort and limited prosthetic function are the main reasons for abandonment especially in transhumeral amputees. Shoulder straps and harnesses within conventional socket designs may not only lead to pain and skin irritations at the contralateral shoulder but also limit the range of motion of the shoulder joint and therefore prosthetic function.

A preliminary study on characterisation of finger interface kinetics using a pressure and shear sensor system.

BACKGROUND: Our hands constantly handle objects throughout our lives, where a crucial component of this interaction is the detection of grasping (pressure) and slipping (shear) of the object. While there have been a large amount of studies using pressure sensors for grasping detection, synchronised pressure and shear detection at the finger/object interface is still needed. OBJECTIVES: This study aims to assess the feasibility of a sensor system designed to detect both pressure and shear at the fingertip/object interface via a single subject test. STUDY DESIGN: Descriptive study, proof of concept. METHODS: One healthy subject participated in the study and was asked to perform a single finger test protocol and a simple hand test protocol. The corresponding multidirectional loads at the fingertip/object interface were measured in real time using a pressure and shear sensor system. RESULTS: Results from the finger test protocol show peak values of up to approximately 50 kPa (5 N) and 30 kPa (3 N) of pressure for each test, respectively. Results from the hand test protocol show a pressure and shear profile that shows a large increase in grip force during the initial grasping of the object, with a peak pressure of approximately 50 kPa (5 N). The pressure and shear profile demonstrates that the load is not evenly distributed across all digits. CONCLUSION: This study provides evidence that the reported sensor system has sufficient resolution, dynamic response and load capability to capture biomechanical information during basic protocols and hand-grasping tasks. Clinical relevance The presented sensor system could be potentially used as a tool for measuring and evaluating hand function and could be incorporated into a prosthetic hand as a tactile feedback system.

Broadband Prosthetic Interfaces: Combining Nerve Transfers and Implantable Multichannel EMG Technology to Decode Spinal Motor Neuron Activity.

Modern robotic hands/upper limbs may replace multiple degrees of freedom of extremity function. However, their intuitive use requires a high number of control signals, which current man-machine interfaces do not provide. Here, we discuss a broadband control interface that combines targeted muscle reinnervation, implantable multichannel electromyographic sensors, and advanced decoding to address the increasing capabilities of modern robotic limbs. With targeted muscle reinnervation, nerves that have lost their targets due to an amputation are surgically transferred to residual stump muscles to increase the number of intuitive prosthetic control signals. This surgery re-establishes a nerve-muscle connection that is used for sensing nerve activity with myoelectric interfaces. Moreover, the nerve transfer determines neurophysiological effects, such as muscular hyper-reinnervation and cortical reafferentation that can be exploited by the myoelectric interface. Modern implantable multichannel EMG sensors provide signals from which it is possible to disentangle the behavior of single motor neurons. Recent studies have shown that the neural drive to muscles can be decoded from these signals and thereby the user's intention can be reliably estimated. By combining these concepts in chronic implants and embedded electronics, we believe that it is in principle possible to establish a broadband man-machine interface, with specific applications in prosthesis control. This perspective illustrates this concept, based on combining advanced surgical techniques with recording hardware and processing algorithms. Here we describe the scientific evidence for this concept, current state of investigations, challenges, and alternative approaches to improve current prosthetic interfaces.

Progress Toward Optimizing Prosthetic Socket Fit and Suspension Using Elevated Vacuum to Promote Residual Limb Health.

Objective: Prosthetic sockets are custom made for each amputee, yet there are no quantitative tools to determine the appropriateness of socket fit. Ensuring a proper socket fit can have significant effects on the health of residual limb soft tissues and overall function and acceptance of the prosthetic limb. Previous work found that elevated vacuum pressure data can detect movement between the residual limb and the prosthetic socket; however, the correlation between the two was specific to each user. The overall objective of this work is to determine the relationship between elevated vacuum pressure deviations and prosthetic socket fit. Approach: A tension compression machine was used to apply repeated controlled forces onto a residual limb model with sockets of different internal volume. Results: The vacuum pressure-displacement relationship was dependent on socket fit. The vacuum pressure data were sensitive enough to detect differences of 1.5% global volume and can likely detect differences even smaller. Limb motion was reduced as surface area of contact between the limb model and socket was maximized. Innovation: The results suggest that elevated vacuum pressure data provide information to quantify socket fit. Conclusions: This study provides evidence that the use of elevated vacuum pressure data may provide a method for prosthetists to quantify and monitor socket fit. Future studies should investigate the relationship between socket fit, limb motion, and limb health to define optimal socket fit parameters.

Characteristics of a volume-adjustable compression chamber for transradial prosthetic interface.

In the transradial limb-socket contact interface, the physiological properties and prosthetic operating habits of the residual limb might affect the comfort and functionality of the prosthesis. To enhance the comfort and functionality of the interface, a frame-type socket with four volume-adjustable compression chambers was proposed for the transradial amputation level. The contact pressure of the limb-socket interface was adjusted by the volume changes in the chambers and controlled by a vacuum pump and the corresponding control system. The parameters of the chamber were designed in accordance with the biomechanics of the forearm soft tissue. The chamber with a negative stiffness characteristic was theoretically compared with the chamber with a positive stiffness characteristic. The results showed that the former had a superior performance to the latter in safety and pump performance requirements. A physical model of the transradial frame-type prosthetic interface was also manufactured with four negative stiffness chambers. The experimental results showed that this new prosthetic interface achieved more fitting time and better performance in comfort and functionality than the fixed frame-type socket. This new prosthetic interface with volume-adjustable compression chambers might be an alternative choice for transradial amputees.

Biomechanical design considerations for transradial prosthetic interface: A review.

Traditional function and comfort assessment of transradial prostheses pay scant attention to prosthetic interface. With better understanding of the biomechanics of prosthetic interface comes better efficiency and safety for interface design; in this way, amputees are more likely to accept prosthetic usage. This review attempts to provide design and selection criteria of transradial interface for prosthetists and clinicians. Various transradial socket types in the literature were chronologically reviewed. Biomechanical discussion of transradial prosthetic interface design from an engineering point of view was also done. Suspension control, range of motion, stability, as well as comfort and safety of socket designs have been considered in varying degrees in the literature. The human-machine interface design should change from traditional "socket design" to new "interface design." From anatomy and physiology to biomechanics of the transradial residual limb, the force and motion transfer, together with comfort and safety, are the two main aspects in prosthetic interface design. Load distribution and transmission should mainly rely on achieving additional skeletal control through targeted soft tissue relief. Biomechanics of the residual limb soft tissues should be studied to find the relationship between mechanical properties and the comfort and safety of soft tissues.

Marker-based method to measure movement between the residual limb and a transtibial prosthetic socket.

BACKGROUND: Limb movement between the residuum and socket continues to be an underlying factor in limb health, prosthetic comfort, and gait performance yet techniques to measure this have been underdeveloped. OBJECTIVES: Develop a method to measure motion between the residual limb and a transtibial prosthetic socket. STUDY DESIGN: Single subject, repeated measures with mathematical modeling. METHODS: The gait of a participant with transtibial amputation was recorded using a motion capture system using a marker set that included arrays on the anterior distal tibia and the lateral epicondyle of the femur. The proximal or distal translation, anterior or posterior translation, and angular movements were quantified. A random Monte Carlo simulation based on the precision of the motion capture system and a model of the bone moving under the skin explored the technique's accuracy. Residual limb tissue stiffness was modeled as a linear spring based on data from Papaioannou et al. RESULTS: Residuum movement relative to the socket went through ~30 mm, 18 mm, and 15° range of motion. Root mean squared errors were 5.47 mm, 1.86 mm, and 0.75° when considering the modeled bone-skin movement in the proximal or distal, anterior or posterior, and angular directions, respectively. CONCLUSION: The measured movement was greater than the root mean squared error, indicating that this method can measure motion between the residuum and socket. CLINICAL RELEVANCE: The ability to quantify movement between the residual limb and the prosthetic socket will improve prosthetic treatment through the evaluation of different prosthetic suspensions, socket designs, and motor control of the prosthetic interface.

Interface pressure in transtibial socket during ascent and descent on stairs and its effect on patient satisfaction.

BACKGROUND: Transtibial amputees encounter stairs and steps during their daily activities. The excessive pressure between residual limb/socket may reduce the walking capability of transtibial prosthetic users during ascent and descent on stairs. The purposes of the research were to evaluate the interface pressure between Dermo (shuttle lock) and Seal-In X5 (prosthetic valve) interface systems during stair ascent and descent, and to determine their satisfaction effects on users. METHODS: Ten amputees with unilateral transtibial amputation participated in the study. Interface pressure was recorded with F-socket transducer (9811E) during stair ascent and descent at self-selected speed. Each participant filled in a questionnaire about satisfaction and problems encountered with the use of the two interface systems. FINDINGS: The resultant mean peak pressure (kPa) was significantly lower for the Dermo interface system compared to that of the Seal-In X5 interface system at the anterior, posterior and medial regions during stair ascent (63.14 vs. 80.14, 63.14 vs. 90.44, 49.21 vs. 66.04, respectively) and descent (67.11 vs. 80.41, 64.12 vs. 88.24, 47.33 vs. 65.11, respectively). Significant statistical difference existed between the two interface systems in terms of satisfaction and problems encountered (P<0.05). INTERPRETATION: The Dermo interface system caused less pressure within the prosthetic socket compared to the Seal-In X5 interface system during stair negotiation. The qualitative survey also showed that the prosthesis users experienced fewer problems and increased satisfaction with the Dermo interface system.