Predictive prosthetic socket design: part 2\u2014generating person-specific candidate designs using multi-objective genetic algorithms

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

Review objective The objective of this systematic review is to synthesise the best available evidence informing the effects of prosthetic socket design on outcomes of function, mobility, comfort and pain, energy expenditure, prosthetic and health related quality of life of adults with a trans-tibial amputation. Specifically, the review will consider studies evaluating the effects comparing the contemporary total surface bearing (TSB) socket design with the more traditional specific surface bearing (SSB) socket design Inclusion criteria Types of participants This review will consider adult trans-tibial amputees 18 years or older, with acquired or congenital limb loss irrespective of the aetiology, gender or the presence of co-morbidities using prostheses with either the contemporary total surface bearing (TSB) socket design or the traditional specific surface bearing (SSB) socket design. Each of the studies considered for inclusion will have documented study populations utilising both TSB and SSB socket designs within the study. Types of interventions The intervention of interest is the use of TSB socket. This is the ‘hydro static’ design or ‘limited load bearing’ often using silicon or gel liner interface, with suspension achieved via distal attachment of pin and lock or lanyard, expulsion valve and sleeve, vacuum assisted, integrated membrane seal or a combination of these. The comparative intervention will be the use of a SSB socket. This is often referred to as PTB, PTS, PTB-SC, PTK or KBM, typically utilising soft foam liner interface paired with supracondylar suspension. Types of outcomes This review will consider studies that include but will not be limited to the following outcomes: • Function and Mobility measured for example using Amputee Activity Score (AAS) or Locomotor Capabilities Index (LCI-5) or Timed Walk Tests (TWTs) or Step Activity Monitor (SAM); • Comfort and Pain measured for example using Socket Comfort Score (SCS) or Brief Pain Inventory (BPI); • Quality of Life including: Prosthetic Related Quality of Life (PRQoL) measured for example using Prosthetic Evaluation Questionnaire (PEQ) and Health Related Quality of Life (HRQoL) measured for example using Trinity Amputation & Prosthesis Experience Scales (TAPES) or Short Form 36 (SF-36); • Energy Expenditure measured for example using Physiological Cost Index (PCI).

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.

Limb amputation causes significant challenges for patients in achieving effective mobility and functionality through prosthetic limbs. The prosthetic socket plays a pivotal role in the success of rehabilitation. This review explores the current advancements in prosthetic socket design and fabrication, focusing on traditional techniques like casting and lamination, and emerging technologies such as 3D printing and computer-aided design (CAD). By comparing these methods, this review highlights the advantages, limitations, and suitability for different clinical needs. This article discusses the importance of pressure distribution in socket design, emphasizing the need to relieve pressure in sensitive areas to prevent skin complications. It also examines the materials used in socket fabrication, from high-density polymers to advanced composites, assessing their impact on patient comfort and prosthetic performance. Additionally, we discuss the challenges practitioners face in prosthetic care, particularly in low-resource settings, and propose potential solutions through innovative techniques and materials. Advancements in computational modeling improved socket design and validation, enhancing patient comfort and improving the overall biomechanical interaction between the prosthesis and the user. The manuscript concludes by identifying future research opportunities, particularly in personalized prosthetic design and the integration of smart materials, to further enhance the comfort, functionality, and accessibility of prosthetic sockets.

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.

This review investigates the opportunities and challenges of interdisciplinary research in upper limb prosthetic (ULP) socket design and manufacturing, which is crucial for improving the lives of individuals with limb loss. By integrating various disciplines, such as engineering, materials science, biomechanics, and health care, with emerging technologies such as 3D printing, artificial intelligence (AI), and virtual reality (VR), interdisciplinary collaboration can foster innovative solutions tailored to users’ diverse needs. Despite the immense potential, interdisciplinary research faces challenges in effective communication, collaboration, and evaluation. This review analyses pertinent case studies and discusses the implications of interdisciplinary research, emphasizing the importance of fostering a shared understanding, open communication, and institutional innovation. By examining technological advancements, user satisfaction, and prosthetic device usage in various interdisciplinary research examples, invaluable insights and direction for researchers and professionals seeking to contribute to this transformative field are provided. Addressing the challenges and capitalizing on the opportunities offered by interdisciplinary research can significantly improve upper limb prosthetic socket design and manufacturing, ultimately enhancing the quality of life for users worldwide.

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.

The large numbers of terrorist attacks and wars in Iraq led to increase the numbers of amputees. However, typically a large number of the amputations are trans-femoral or above knee (AK). In this work, manufacturing a socket by using new method (REVO FIT SOLUTION) for manufacturing trans-femoral prosthetic socket by two molding. The main objectives of this work is to design and manufacturing of above knee prosthetic socket by revo fit solution method to increase suspension, decrease weight of socket and easier to doffing and donning especially for the elderly. The experimental work included subjecting the socket materials to tensile and fatigue testing. The results show that the mechanical properties for (4 layers of carbon fiber) are бult =213MPa, бy =135MPa and E=3.5GPa. The Fatigue life equation for carbon fiber are б=739.6 (Nf)-0.13 and The fatigue limit are 90 MPa The data of gait cycle (force plate) and Interface pressure between the socket and the residual limb was calculated using F-Socket device, the pressure in anterior region equal to (222Kpa)between the socket and the residual limb for patient(male) suffering from above knee right leg amputation and age(42)year. The finite element technique (ANSYS) is used to analyze the model of prosthetic socket and calculate the safety factor, equivalent (Von Mises) stress, and total deformation. The obtained results from ANSYS gave the profile of safety factor of fatigue, for AK with carbon fiber is (1.26).

The prosthetic socket serves as a critical interface between the human body and the prosthesis; however, conventional sockets are associated with a skin breakdown risk exceeding 60%. To address this issue, we conducted a biomechanical analysis of the limb-socket interface aiming to enhance both comfort and functional performance. Medical imaging scans of three hip disarticulation amputees were combined with reverse engineering techniques and finite element analysis to reconstruct a 3D model of the residual limb and socket, enabling stress distribution assessment. A novel socket design was proposed, leveraging computer-aided digital modeling and 3D printing to replace conventional manual fabrication, thereby enhancing fit, comfort, and manufacturing precision. The novel socket reduced stress concentrations at the limb-socket interface by 16.97% overall, with nearly a 25% reduction observed at the bottom of the residual limb. Experimental pressure distribution measurements exhibited a high degree of consistency with finite element analysis simulations ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mover> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> <mml:mo stretchy="true">¯</mml:mo> </mml:mover> </mml:mrow> </mml:math> = 0.991). Furthermore, the socket significantly improved gait symmetry in prosthesis users. The inverse design methodology based on digital modeling, coupled with biomechanical analysis, offers an effective strategy for optimizing the structural design and fabrication process of hip prosthetic sockets.

Achieving a best-fit prosthetic socket is essential to comfort, functional performance, and long-term residual limb health in lower-limb amputees. To our knowledge, no previous study has quantitatively compared in vivo residual limb geometry under vacuum versus non-vacuum conditions using high-resolution computed tomography (CT). In this patient-specific case study of a bilateral knee-disarticulation (KD) amputee, both residual limbs were scanned under standardized conditions: one enclosed in a vacuum-compressed sleeve and the contralateral limb untreated as a natural control, thereby minimizing inter-subject variability. CT-based 3D reconstructions enabled volumetric and cross-sectional quantification, including symmetry/asymmetry analysis of paired limbs, while finite element analysis (FEA) assessed the biomechanical consequences for socket performance. Vacuum application resulted in a 4.1% reduction in total limb volume and a 5.3% reduction in mid-thigh cross-sectional area, with regionally asymmetric displacement of soft tissues. FEA demonstrated that vacuum-induced geometry reduced peak Von Mises stresses (27.43 MPa to 15.83 MPa), minimized maximum displacement (1.72 mm to 0.88 mm), and improved minimum factor of safety (~2.0 to ~3.0), while homogenizing contact pressure distribution (peak fell from 2.42 to 1.28 N/mm2). These findings provide preliminary CT-based evidence that vacuum application induces measurable morphological adaptations with implications for socket conformity, comfort, and load transfer. While limited to a single patient, this study highlights the potential of vacuum-induced modeling to inform personalized prosthetic socket design.

Patellar tendon bearing (PTB) and total surface bearing (TSB) sockets have been used respectively in the prosthetic treatment of 20 trans-tibial amputees to investigate the effectiveness of both sockets on prosthetic fitting and rehabilitation. Data analysis showed that prostheses with TSB sockets were lighter than the prostheses with PTB sockets and better suspension was obtained from TSB prosthetic socket (p<0.05). It was also found that weight acceptance on the amputated side advanced to a more normal value with TSB prostheses (p<0.05). There was a statistically significant difference between the two socket types in walking and in other ambulation activities except sitting and standing up from a chair, in favour of the TSB socket (p<0.05). Consequently, due to the outcome of this study it can be said that TSB prosthetic sockets can be used effectively in the rehabilitation of trans-tibial amputees.

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.

A very attractive advantage of manufacturing prosthetic sockets using solid freeform fabrication is the freedom to introduce design solutions that would be difficult to implement using traditional manufacturing techniques. Such is the case with compliant features embedded in amputee prosthetic sockets to relieve contact pressure at the residual limb-socket interface. The purpose of this study was to present a framework for designing compliant features to be incorporated into transtibial sockets and manufacturing prototypes using selective laser sintering (SLS) and Duraform material. The design process included identifying optimal compliant features using topology optimization algorithms and integrating these features within the geometry of the socket model. Using this process, a compliant feature consisting of spiral beams and a supporting external structure was identified. To assess its effectiveness in reducing residual limb-socket interface pressure, a case study was conducted using SLS manufactured prototypes to quantify the difference in interface pressure while a patient walked at his self-selected pace with one noncompliant and two different compliant sockets. The pressure measurements were performed using thin pressure transducers located at the distal tibia and fibula head. The measurements revealed that the socket with the greatest compliance reduced the average and peak pressure by 22% and 45% at the anterior side distal tibia, respectively, and 19% and 23% at the lateral side of the fibula head, respectively. These results indicate that the integration of compliant features within the socket structure is an effective way to reduce potentially harmful contact pressure and increase patient comfort.

Prosthetic gel liners are often prescribed for persons with lower-limb amputations to make the prosthetic socket more comfortable. However, their effects on residual limb pressures and gait characteristics have not been thoroughly explored. This study investigated the effects of gel liner thickness on peak socket pressures and gait patterns of persons with unilateral transtibial amputations. Pressure and quantitative gait data were acquired while subjects walked on liners of two different uniform thicknesses. Fibular head peak pressures were reduced (p = 0.04) with the thicker liner by an average of 26 +/- 21%, while the vertical ground reaction force (GRF) loading peak increased 3 +/- 3% (p = 0.02). Most subjects perceived increased comfort within the prosthetic socket with the thicker liner, which may be associated with the reduced fibular head peak pressures. Additionally, while the thicker liner presumably increased comfort by providing a more compliant limb-socket interface, the higher compliance may have reduced force and vibration feedback to the residual limb and contributed to the larger vertical GRF loading peaks. We conclude that determining optimal gel liner thickness for a particular individual will require further investigations to better identify and understand the compromises that occur between user perception, residual-limb pressure distribution, and gait biomechanics.

A software package, written in Pascal, whkh automates the shape management process associated with fitting prosthetic sockets to transtibial (below-knee) amputees, is described. The system allows an operator to apply global and piecewise transformations, based upon clinkal measurements, to a primitive socket database. These transformations yield a modified socket database which defines the surface shape of a positive socket mold over which an amputee's prosthetic socket is formed. The mold is replicated using a computer numerkally controled milling machine, with the final socket being formed over this mold by a specialized vacuum former. Preliminary clinical trials indkate that this automated approach to shape management yields comfortable prostheses, with savings in time and cost over the traditional methods of prosthesis manufacture.