Quantitative Evaluation of Vacuum-Induced Morphological Changes in Knee-Disarticulation: A Case Study for Personalized Prosthetic Socket Design

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. Develop a method to measure motion between the residual limb and a transtibial prosthetic socket. Single subject, repeated measures with mathematical modeling. 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. 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. The measured movement was greater than the root mean squared error, indicating that this method can measure motion between the residuum and socket. 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.

There is a rapid growth in limb amputation, particularly of the lower limb has been observed over the years due to road traffic accidents (TRA), infections and uncontrolled diabetes in developing countries. Peripheral vascular diseases are the leading cause of amputation in the developed countries. The prosthetic socket design aims to maximize comfort and functionality for an amputee towards ambulation. Prosthetic socket fit has a great impact on the amputee’s quality of life. The body-weight of an amputee transfers optimally through the socket to the ground during the different phases of the gait pattern/cycle and is directly is in contact with the human residual limb while prosthesis is on. Thus, socket designs play an important role in prosthetic rehabilitation; encapsulating the residual limb becomes the weight-bearing structure within the residuum–prosthesis complex. Additionally, biomechanical considerations in the socket design with pressure distribution to tolerant areas and relief to the sensitive part of the stump/residuum promote greater comfort. It acts as an interface between the residual limb and the prosthesis. The socket fit cannot be the same for all, as it differs with the individual level of amputation, shape, and dimension of the residual limb. The goal of prosthetic socket must fulfill the user's needs of increased Range of Motion (ROM) and total suspension to achieve near-normal gait pattern and optimal functioning. The knowledge of socket biomechanics, materials, and residual limb behavior improve the function, comfort, and satisfaction of the end-users. Currently, the Patellar Tendon Bearing (PTB), Total Surface Bearing (TSB), Silicone Socket Suspension (3S), and Vacuum-assisted Socket Suspension (VASS) socket designs are being used globally to optimize the amputee functioning. The clinician's expertise plays an important role in deciding the type of socket. Prosthetic socket design with the feature of self-adaptation in real time during various gait phases is one of the challenges for future research.KeywordsProsthesisSocketRehabilitationTranstibialHealthcareAmputeeTechnologyDesignBiomechanics

In post-amputation rehabilitation, a common goal is to return to ambulation using a prosthetic limb, suspended by a customised socket. Prosthetic socket design aims to optimise load transfer between the residual limb and mechanical limb, by customisation to the user. This is a time-consuming process, and with the increase in people requiring these prosthetics, it is vital that these personalised devices can be produced rapidly while maintaining excellent fit, to maximise function and comfort. Prosthetic sockets are designed by capturing the residual limb’s shape and applying a series of geometrical modifications, called rectifications. Expert knowledge is required to achieve a comfortable fit in this iterative process. A variety of rectifications can be made, grouped into established strategies [e.g. in transtibial sockets: patellar tendon bearing (PTB) and total surface bearing (TSB)], creating a complex design space. To date, adoption of advanced engineering solutions to support fitting has been limited. One method is numerical optimisation, which allows the designer a number of likely candidate solutions to start the design process. Numerical optimisation is commonly used in many industries but not prevalent in the design of prosthetic sockets. This paper therefore presents candidate shape optimisation methods which might benefit the prosthetist and the limb user, by blending the state of the art from prosthetic mechanical design, surrogate modelling and evolutionary computation. The result of the analysis is a series of prosthetic socket designs that preferentially load and unload the pressure tolerant and intolerant regions of the residual limb. This spectrum is bounded by the general forms of the PTB and TSB designs, with a series of variations in between that represent a compromise between these accepted approaches. This results in a difference in pressure of up to 31 kPa over the fibula head and 14 kPa over the residuum tip. The presented methods would allow a trained prosthetist to rapidly assess these likely candidates and then to make final detailed modifications and fine-tuning. Importantly, insights gained about the design should be seen as a compliment, not a replacement, for the prosthetist’s skill and experience. We propose instead that this method might reduce the time spent on the early stages of socket design and allow prosthetists to focus on the most skilled and creative tasks of fine-tuning the design, in face-to-face consultation with their client.

Accurate modeling of residual limb geometry is essential for prosthetic socket design, yet current scanning techniques can be costly, operator-dependent, or impractical for repeated clinical use. This study presents a fully automated, low-cost photogrammetry workflow capable of generating metrically accurate 3D models of lower-limb residual limbs using video and still images acquired with a standard smartphone or a full-frame digital camera. The pipeline integrates adaptive frame selection, deep learning-based background removal, robust metric scaling via ArUco markers, and open-source Structure-from-Motion and Multi-View Stereo reconstruction, requiring no manual post-processing or proprietary software. Accuracy and repeatability were evaluated using four 3D-printed limb phantoms and high-resolution CT-derived meshes as ground truth. Smartphone video and full-frame camera acquisitions achieved sub-millimeter surface accuracy, volume and perimeter errors within ±1%, and high inter-session repeatability, all within clinically accepted thresholds for prosthetic socket fabrication. In contrast, smartphone still-photo reconstructions showed larger deviations and reduced stability. Acquisition time was under five minutes, and complete reconstruction required approximately 1 h and 30 min. These results demonstrate that smartphone video-based photogrammetry provides a practical, scalable, and clinically viable alternative for residual limb modeling, particularly in resource-constrained or remote care settings.

Dermatological problems of amputees due to excessive heat generation within the prosthetic socket can lead to ulcers, cysts, sores, infections, and tumors. Approximately two-thirds of those suffering from dermatological problems are lower limb amputees. Currently there is research into developing new prosthetic socket designs with lighter or ventilated material to alleviate these problems. However, these designs have to be tested to ensure the amputee can rely on the device to be mechanically sound. The proposed dynamic gait simulator is designed to measure prosthetic socket strain distribution for a range of ground reaction forces and gait velocities so that mechanical integrity of these new designs can be evaluated, as well as assist training of new prosthetists in socket design.

Numerical simulation and experimental testing for static failure prediction in additively manufactured below-knee prosthetic sockets.

To perform activities of daily living (ADL), people with lower limb amputation depend on the prosthetic socket for stability and proprioceptive feedback. Poorly fitting sockets can cause discomfort, pain, limb tissue injuries, limited device usage, and potential rejection. Semi-passively controlled adjustable socket technologies exist, but these depend upon the user's perception to determine safe interfacial pressure levels. This paper presents a framework for automatic control of an adjustable transtibial prosthetic socket that enables active adaptation of residuum-socket interfacial loading through localized actuators, based on soft tissue injury risk estimation. Using finite element analysis, local interfacial pressure vs. compressive tissue strain relationships were estimated for three discrete anatomical actuator locations, for tissue injury risk assessment within a control structure. Generalized Predictive Control of multiple actuators was implemented to maintain interfacial pressure within estimated safe and functional limits. Controller simulation predicted satisfactory dynamic performance in several scenarios. Actuation rates of 0.06-1.51kPa/s with 0.67% maximum overshoot, and 0.75-1.58kPa/s were estimated for continuous walking, and for a demonstrative loading sequence of ADL, respectively. The developed platform could be useful for extending recent efforts in adjustable lower limb prosthetic socket design, particularly for individuals with residuum sensory impairment.

Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) are well-known medications commonly prescribed for type 2 diabetes management and pharmacologic management of obesity. While GLP-1 RAs have many positive effects on glycemic control and cardiovascular health, the secondary effect of weight loss can present a challenge in maintaining optimal prosthesis fitting and functionality among individuals with prosthetic limbs. More specifically, weight loss can lead to decreased muscle mass and volume of the residual limb, resulting in loosening of the prosthesis. In turn, individuals often require more frequent prosthetic adjustments to ensure their safety and comfort while using the prosthetic device. Herein, we describe three cases of semaglutide use in patients with prosthetic limbs who subsequently presented with a variety of complications including skin breakdown, disproportionate residual limb volume loss, decreased prosthetic use and increased residual limb pain. Such "Ozempic® limbs" have not yet been reported in the literature. These observations suggest that further research in GLP-1 RA selection is required for persons with amputation, as well as increased patient education regarding the unique complications.

Prosthetic sockets and the related suspension systems play key roles in functional restoration for individuals with limb loss; a good fit of the socket-suspension systems (SSSs) is critical to avoid unexpected skin breakdown. However, maintaining a good fit between the limb and SSS is challenging due to daily volume changes in the residual limb. In clinical practice, the fit of the SSS is monitored only through haptic feedback from the user. While important, this subjective feedback is often unreliable and inaccurate. Several automatic SSS monitoring approaches have been proposed, but widespread adoption has been limited by related high costs and difficulty of use. To address these issues, we designed a wearable SSS monitor that can be adopted for any SSS using liners without requiring permanent modifications of the SSS. Using a tiny magnetic disk as a marker, we were able to monitor the relative displacement between the residual limb (represented by the liner) and the prosthetic socket along the proximal-distal direction using field orientation measurement sensors. We conducted bench tests to validate the high accuracy of the wearable SSS monitor and demonstrated the capability of tracking SSS fit changes during locomotion without permanent modification of the SSS.

Recently, three-dimensional models 3DM in the prosthetics field gained popularity, especially in the context of residual limb shape creation resulting from collecting medical images in Digital Imaging and Communications in Medicine DICOM format from a magnetic resonance imaging MRI after image processing accurately. In this study, a three-dimensional model of the residual limb for a patient with transtibial amputation was realized with the integration of artificial intelligence and a computer vision approach demonstrating the benefits of AI segmentation tools and artificial algorithms to generate higher accuracy three-dimensional model before prosthetic socket design or in case of comparison the 3D model generated from MRI with another 3D model generated from another technique, where a residual limb of a 23 years old male patient with amputation in the left leg wearing a prosthetic socket liner, and having 62 kg weight, 168 cm height, with high activity level. The patient was scanned using GE Medical Systems, 1,5 Tesla Signa Excite. MRI images in DICOM format were read to retrieve essential metadata such as pixel spacing and slice thickness. These images were processed to obtain a model that reflects the real shape of the residual limb using a specific algorithm, and the 3D model was extracted using AI segmentation tools. The obtained 3D model result with high resolution proves the potential of the artificial intelligence approach with deep learning to reconstruct 3D models concluding that AI has an instrumental role in medical image analysis, particularly in the areas of organ and tissue classification and segmentation., thus generating automatic and repetitive a 3D model.

Para Surfing Performance in Athletes With Lower Limb Amputations - A Cross-Sectional Study

Impact of Incision Technique and Post-operative Factors on Time to Prosthetic Fitting following Transtibial Amputation: A SwedeAmp Registry Study.

ABSTRACTThe snug fit of a prosthetic socket over the residual limb can disturb thermal balance and put skin integrity in jeopardy by providing an unpleasant and infectious environment. The prototype of a temperature measurement and control (TM&C) system was previously introduced to resolve thermal problems related to prostheses. This study evaluates its clinical application in a setting with reversal, single subject design. The TM&C system was installed on a fabricated prosthetic socket of a man with unilateral transtibial amputation. Skin temperature of the residual limb without prosthesis at baseline and with prosthesis during rest and walking was evaluated. The thermal sense and thermal comfort of the participant were also evaluated. The results showed different skin temperature around the residual limb with a temperature decrease tendency from proximal to distal. The TM&C system decreased skin temperature rise after prosthesis wearing. The same situation occurred during walking, but the thermal power of the TM&C system was insufficient to overcome heat build-up in some regions of the residual limb. The participant reported no significant change of thermal sense and thermal comfort. Further investigations are warranted to examine thermography pattern of the residual limb, thermal sense, and thermal comfort in people with amputation.

Automatic segmentation of magnetic resonance images of the trans-femoral residual limb

Between 60 and 80 percent of amputees typically report inadequate fit between their residual limb and their prosthetic socket. Inadequate fit of a prosthetic socket can result not only in secondary medical problems, but can also lead to increased financial burden as the patient is forced to undergo repeated adjustment of the prosthesis. To address this problem, studies have been undertaken to investigate the feasibility of adjustable prosthetic sockets using embedded shape-memory alloy (SMA) wire. Embedded SMA actuators will allow the socket to be adjusted to the patient’s stump as needed for a better fit. It is believed that this method will not only reduce replacement costs (excluding normal wear and tear), but will minimize secondary medical problems due to poor fit. and improve overall patient satisfaction with the prosthesis. Preliminary tests using Nitinol SMA wire on a surrogate socket have shown that a diametral reduction of 4 percent is possible. Present research entails SMA characterization; selection of the appropriate SMA for clinical use; experimentation with location, orientation, and connection of the SMA within the socket wall; and heating of the SMA within the polyethylene matrix.