Socket Fit Research Articles

Evaluating the Effectiveness of Transtibial Prosthetic Socket Shape Design Using Artificial Intelligence: A Clinical Comparison With Traditional Plaster Cast Socket Designs

ObjectiveTo investigate the feasibility of creating an artificial intelligence (AI) algorithm to enhance prosthetic socket shapes for transtibial prostheses, aiming for a less operator-dependent, standardized approach. DesignThe study comprised 2 phases: first, developing an AI algorithm in a cross-sectional study to predict prosthetic socket shapes. Second, testing the AI-predicted digitally measured and standardized designed (DMSD) prosthetic socket against a manually measured and designed (MMD) prosthetic socket in a 2-week within-subject cross-sectional study. SettingThe study was done at the rehabilitation department of the Radboud University Medical Center in Nijmegen, the Netherlands. ParticipantsThe AI algorithm was developed using retrospective data from 116 patients from a Dutch orthopedic company, OIM Orthopedie, and tested on 10 randomly selected participants from Papenburg Orthopedie. InterventionsUtilization of an AI algorithm to enhance the shape of a transtibial prosthetic socket. Main Outcome MeasuresThe algorithm was optimized to minimize the error in the test set. Participants’ socket comfort score and fitting ratings from an independent physiotherapist and prosthetist were collected. ResultsPredicted prosthetic shapes deviated by 2.51 mm from the actual designs. In total, 8 of 10 DMSD and all 10 MMD-prosthetic sockets were satisfactory for home testing. Participants rated DMSD-prosthetic sockets at 7.1 ± 2.2 (n=8) and MMD-prosthetic sockets at 6.6 ± 1.2 (n=10) on average. ConclusionsThe study demonstrates promising results for using an AI algorithm in prosthetic socket design, but long-term effectiveness and refinement for improved comfort and fit in more deviant cases are necessary.

The Overlay, a New Solution for Volume Variations in the Residual Limb for Individuals with a Transtibial Amputation.

The company Ethnocare has developed the Overlay, a new pneumatic solution for managing volumetric variations (VVs) of the residual limb (RL) in transtibial amputees (TTAs), which improves socket fitting. However, the impact of the Overlay during functional tasks and on the comfort and pain felt in the RL is unknown. 8 TTAs participated in two evaluations, separated by two weeks. We measured compensatory strategies (CS) using spatio-temporal parameters and three-dimensional lower limb kinematics and kinetics during gait and sit-to-stand (STS) tasks. During each visit, the participant carried out our protocol while wearing the Overlay and prosthetic folds (PFs), the most common solution to VV. Between each task, comfort and pain felt were assessed using visual analog scales. While walking, the cadence with the Overlay was 105 steps/min, while it was 101 steps/min with PFs (p = 0.021). During 35% and 55% of the STS cycle, less hip flexion was observed while wearing the Overlay compared to PFs (p = 0.004). We found asymmetry coefficients of 13.9% with the Overlay and 17% with PFs during the STS (p = 0.016) task. Pain (p = 0.031), comfort (p = 0.017), and satisfaction (p = 0.041) were better with the Overlay during the second visit. The Overlay's impact is similar to PFs' but provides less pain and better comfort.

The Dynamic Donning Technique of Prosthetic Liners

ABSTRACT Introduction Prosthetic liners are widely used for a variety of indications such as improving prosthetic socket fit and suspension. However, these are associated with complications affecting the skin, including skin rubs, breakdown, and ulceration. Methods and Discussion We outline the splinting effect of prosthetic liners as a possible contributing factor that results in increased shear during joint motion and propose a simple liner donning technique to minimize these shear forces by spreading liner/skin tension over the whole range of motion of the proximal joint. Clinical Relevance The proposed dynamic donning technique would minimize the risk of skin ulcerations and improve joint range of motion in prosthetic limb users.

Comparison of Socket Geometry, Socket Comfort, and Patient Experience between Manually- and Digitally-Designed Prosthetic Sockets for Lower-Limb Amputees: A Feasibility Study

This shift in practice may change the socket geometry and fit; however, to what extent is unknown. Thus, the aim of this study was to explore the feasibility of analyzing geometric and clinical differences between digitally- and manually-designed sockets. Nine adult inpatients with below-knee amputation were recruited. Two sockets were 3D printed for each participant from 3D socket models that were developed from: (1) 3D scanning a manually-modified hand-casted positive mold of the residuum; and (2) a digitally-modified 3D scan of the residuum. Manual and digital procedures were compared for three measures: final socket geometry, the Socket Comfort Score, and a patient experience survey. Feasibility data were collected to measure protocol implementation fidelity to inform a future larger study. These data revealed that 89% of participants followed the intended protocol, no participants dropped out, and only one adverse event was report. As no significant geometric differences were found and participants experienced similar comfort scores between manually- and digitally-designed sockets, study feasibility was determined to be successful. Thus, a randomized control trial study will be conducted to draw statistically relevant conclusions from these outcome measures that may provide meaningful information for improving digital design procedures.

Rehabilitative outcomes with preparatory suction prostheses following traumatic Gritti-Stokes amputation: A case series.

Gritti-Stokes amputation (GSA) is a knee disarticulation variant, where the femur is transected at the level of the epicondyle and the patella is fixated to the distal end. GSA results in a long residual limb with little postoperative swelling and less potential for muscular atrophy, so stable limb volume may allow the use of seal-in suction for suspension for preparatory prostheses. The purpose of this case series was to report on the efficacy of seal-in suction preparatory prostheses for 2 adults with traumatic GSA. Between October and December of 2021, 2 participants with unilateral traumatic Gritti-Stokes amputation, who had received seal-in suction suspension for their preparatory prostheses, were recruited. Information was extracted from medical charts regarding prosthetic care and mobility at preparatory and definitive prosthesis evaluation, and participants underwent standardized measurement of their residual limb and prosthesis. Duration of preparatory prosthesis use was >6 months; neither participant reported loss of suspension nor significant complications with socket fit. Participant 1 required socket replacement because of residual limb pain secondary to osteophyte formation, and Participant 2 required component replacement because of weight gain. At definitive prosthesis evaluations, both participants were unlimited community ambulators; both successfully returned to work before provision of their definitive prostheses. Results indicate that seal-in suction suspension may be viable for preparatory prostheses among adults with traumatic GSA, but knee center height discrepancies persist. GSA may yield highly functional outcomes for adults with traumatic amputation. Further research is required to substantiate these findings.

An adaptive prosthetic socket for people with transtibial amputation

It is essential that people with limb amputation maintain proper prosthetic socket fit to prevent injury. Monitoring and adjusting socket fit, for example by removing the prosthesis to add prosthetic socks, is burdensome and can adversely affect users’ function and quality-of-life. This study presents results from take-home testing of a motor-driven adaptive socket that automatically adjusted socket size during walking. A socket fit metric was calculated from inductive sensor measurements of the distance between the elastomeric liner surrounding the residual limb and the socket’s inner surface. A proportional-integral controller was implemented to adjust socket size. When tested on 12 participants with transtibial amputation, the controller was active a mean of 68% of the walking time. In general, participants who walked more than 20 min/day demonstrated greater activity, less doff time, and fewer manual socket size adjustments for the adaptive socket compared with a locked non-adjustable socket and a motor-driven socket that participants adjusted with a smartphone application. Nine of 12 participants reported that they would use a motor-driven adjustable socket if it were available as it would limit their socket fit issues. The size and weight of the adaptive socket were considered the most important variables to improve.

Techniques for Measuring the Fluctuation of Residual Lower Limb Volume in Clinical Practices: A Systematic Review of the Past Four Decades

Increased pressure and shear stress distributions at the limb–socket interface are hypothesised to result from changes in the residual limb shape and volume, which can cause socket fit difficulties. Accurate residual limb volume measurements may aid clinicians in developing strategies to accommodate volume fluctuations. This review primarily aims to analyse the techniques available for measuring the residual lower limb volume that may be used in clinical settings, as documented in the works published over the previous four decades. A comprehensive search of articles in PubMed, ScienceDirect, Web of Science, and Google Scholar identified 904 articles, and further analysis resulted in only 39 articles being chosen to be analysed. Based on the findings, there are nine techniques available to measure the residual limb volume: water displacement, anthropometric measurement, contact probes, optical scanning, spiral X-ray computed tomography (SXCT), magnetic resonance imaging (MRI), ultrasound, laser scanning, and bioimpedance. Considering the variety of techniques for determining residual limb volume, it is critical to choose the ones that best suit clinicians’ objectives, and each technique has potential sources of error that should be avoided by taking precautionary action. A comprehensive study of the measurement techniques is needed since researchers have developed and extensively utilised many new measuring devices, especially handheld 3D laser scanners.

Preliminary characterization of rectification for transradial prosthetic sockets

Achieving proper socket fit is crucial for the effective use of a prosthesis. However, digital socket design lacks standardization and presents a steep learning curve for prosthetists. While research has focused on digital socket design for the lower-limb population, there is a research gap in upper-limb socket design. This study aimed to characterize the design (rectification) process for the transradial socket, specifically the three-quarter Northwestern-style design, towards the development of a more systematic, data-driven socket design approach. Fourteen (n = 14) pairs of unrectified and rectified plaster models were compared. Six common rectification zones were identified through shape analysis, with zones of plaster addition being the most prominent in terms of volume and surface area. A novel 3D vector mapping technique was employed, which revealed that most of the shape changes occurred in the anterior–posterior and proximal–distal directions. Overall, the interquartile range of each rectification zone demonstrated reasonable consistency in terms of volume, surface deviation, and 3D vector representation. The initial findings from this study support the potential for quantitively modelling the transradial socket design process. This opens the door for developing tools for categorizing and predicting socket designs across diverse populations through the application of techniques such as machine learning.

Shape Analysis of Prosthetic Socket Rectification Procedure for Transtibial Amputees

Achieving a comfortable socket residual limb interface is crucial for effective prosthetic rehabilitation, depending on the precise characterisation and fluctuations in the shape and volume of residual limbs. Clinicians rely on subjective and iterative methods for shaping sockets, often involving a trial-and-error approach. This study introduces a framework for measuring, analysing, and comparing residual limb shape and volume using scanned data to facilitate more informed clinical decision-making. Surface scans of 44 transtibial residual limb casts of various sizes and lengths were examined. All scans were spatially aligned to a mid-patella and subjected to analysis using a shape analysis toolbox. Geometric measurements were extracted, with particular attention to significant rectified regions during the cast rectification process. Following PTB guidelines, our analysis revealed substantial alterations, primarily in the mid-patella region, followed by the patellar tendon area. Notably, there was a significant volume change of 6.02% in the region spanning from mid-patella to 25% of the cast length. Beyond this point, linear cast modifications were observed for most amputees up to 60% of the cast length, followed by individual-specific deviations beyond this region. Regardless of residual limb size and length, the modifications applied to positive casts suggested categorising patients into five major groups. This study employs the AmpScan shape analysis tool, to comprehend the cast rectification process used for capturing and assessing the extent of rectification on patients’ residual limb casts. The clinical implications of our research are threefold: (a) the comparison data can serve as training resources for junior prosthetists; (b) this will aid prosthetists in identifying specific regions for rectification and assessing socket fit; (c) it will help in determining optimal timing for prosthetic fitting or replacement.

A pneumatic reconfigurable socket for transtibial amputees.

Many transtibial amputees rate the fit between their residual limb and prosthetic socket as the most critical factor in satisfaction with using their prosthesis. This study aims to address the issue of prosthetic socket fit by reconfiguring the socket shape at the interface of the residual limb and socket. The proposed reconfigurable socket shifts pressure from sensitive areas and compensates for residual limb volume fluctuations, the most important factors in determining a good socket fit. Computed tomography scan images are employed to create the phantom limb of an amputee and to manufacture the reconfigurable socket. The performance of the reconfigurable socket was evaluated both experimentally and numerically using finite element modelling. The study showed that the reconfigurable socket can reduce interface pressure at targeted areas by up to 61%.

A high precision laser scanning system for measuring shape and volume of transtibial amputee residual limbs: Design and validation.

Changes in limb volume and shape among transtibial amputees affects socket fit and comfort. The ability to accurately measure residual limb volume and shape and relate it to comfort could contribute to advances in socket design and overall care. This work designed and validated a novel 3D laser scanner that measures the volume and shape of residual limbs. The system was designed to provide accurate and repeatable scans, minimize scan duration, and account for limb motion during scans. The scanner was first validated using a cylindrical body with a known shape. Mean volumetric errors of 0.17% were found under static conditions, corresponding to a radial spatial resolution of 0.1 mm. Limb scans were also performed on a transtibial amputee and yielded a standard deviation of 8.1 ml (0.7%) across five scans, and a 46 ml (4%) change in limb volume when the socket was doffed after 15 minutes of standing.

A Pneumatically Controlled Prosthetic Socket for Transfemoral Amputees.

Amputees typically experience changes in residual limb volume in their daily lives. It causes an uncomfortable fit of the socket by applying high pressure on the sensitive area of the residual limb or by loosening the socket. In this study, we developed a transfemoral prosthetic socket for above-the-knee amputees that ensures a good socket fit by maintaining uniform and constant contact pressure despite volume changes in the residual limb. The socket has two air bladders in the posterior femoral region, and the pneumatic controller is located on the tibia of the prosthesis. The pneumatic system aims to minimize unstable fitting of the socket and improve walking performance by inflating or deflating the air bladder. The developed socket autonomously maintains the air pressure inside the prosthetic socket at a steady-state error of 3 mmHg or less by adjusting the amount of air in the air bladder via closed-loop control. In the clinical trial, amputee participants walked on flat and inclined surfaces. The displacement between the residual limb and socket during the gait cycle was reduced by up to 33.4% after air injection into the socket. The inflatable bladder increased the knee flexion angle on the affected side, resulting in increased stride length and gait velocity. The pneumatic socket provides a stable and comfortable walking experience not only when walking on flat ground but also on slopes.

Evaluating Feasibility and Durability of the Aero Prosthetic Liner in Transtibial Prosthetic Users.

The choice of prosthetic socket interface material significantly affects user comfort and satisfaction. The Affordable Ethylene-Vinyl Acetate Roll-On (AERO) liner was created with the aim of improving functionality and streamlining the wearing process for users. The purpose of this study was to comprehensively assess user satisfaction, comfort, and durability of the AERO liner and compare it with the common soft Pe-Lite liner. Fourteen individuals with transtibial amputation participated in this three-month randomized crossover trial study. The Prosthesis Evaluation Questionnaire (PEQ), Expanded Socket Comfort Score (ESCS), and liner thickness measurements were used to comprehensively compare the AERO and Pe-Lite liner. The AERO liner demonstrated notable improvements in prosthetic comfort and functionality over Pe-Lite liner. After three months use, there was a significant reduction in reported frustration with the AERO liner (p=0.023, r=0.604) in the PEQ subscale. Specific aspects, such as walking with the prosthesis (p=0.030, r=0.601) and odor perception (p=0.024, d=0.579), favored the use of the AERO liner. The expanded socket comfort score (ESCS) revealed significant superiority for the AERO liner "at best" (p=0.04) and "on average" (p=0.02) after one and three months, respectively. Liner thickness analysis showed significant reductions at the mid-patellar tendon location for the AERO liner at one (0.57±0.48) and three months (0.90±0.69, p=0.01) and in the posterior region after three months (0.63±0.64, p=0.05). Our study highlights the potential advantages of the AERO liner in enhancing comfort and satisfaction. Yet, durability and thinning of the liner when compared to Pe-Lite may be a concern which may eventually affect socket fit. These findings contribute to ongoing efforts to optimize prosthetic interventions and improve the quality of life of individuals with lower limb prosthesis in resource-limited environments.

Perceived Service Quality and User Satisfaction with Orthotic-Prosthetic Devices and Services Among Individual with Physical Disabilities

This research contributes to ongoing efforts to enhance healthcare service quality and improve the well-being of individuals with disabilities, particularly those with physical disabilities relying on orthotic-prosthetic care in their communities. Currently, there is limited evidence available to guide policy, funding decisions, and practitioners in Indonesia. Study participants included adult orthosis/prosthesis users and parents/guardians of children using these devices, all of whom sought services at the Jakarta I Ministry of Health Polytechnic educational clinic in January to June 2023. Subsequently, the socket fabrication, fitting, and evaluation process took place, utilizing purposive sampling for surveys encompassing demographics and the Modified Orthotic Prosthetic User Survey (OPUS) – Client Satisfaction with Devices and Services. 73% of patients reported satisfaction with high-quality Orthotic-Prosthetic devices, while 86% expressed satisfaction with excellent service. This highlights the effectiveness of the Modified Orthotic Prosthetic User Survey (OPUS) in assessing user satisfaction with prosthetic-orthotic devices and services, underscoring the need for ongoing tool refinement.

Assessing Socket Fit Effects on Pressure and Shear at a Transtibial Residuum/Socket Interface.

Fluctuations in residuum volume during daily activities are known to occur in lower-limb amputees. This can cause frequent changes to fit, which cannot be accommodated by commonly-used prosthetic sockets. The real-time effects, if any, of these minor socket fit changes on interface biomechanics have not been studied extensively. Amputees commonly use different layers of socks to accommodate frequent volume fluctuations, enabling adjustment of socket fit. We, thus, altered socket fit levels via addition/removal of sock layers to a transtibial amputee who habitually-donned two-sock layers to mimic relatively looser and tighter socket fits. Interface pressure and shear sensors were placed at known prominent load-bearing sites of the transtibial residuum/socket interface, i.e., patellar tendon (PT), popliteal fossa (PF), and anterior-distal (AD) end, to measure real-time biomechanical interactions during standing and level walking. Although socket fit level was only slightly modified, changes in interface pressure and shear across anatomical sites were still observed. Tighter fit corresponds to notable pressure reduction at AD during early stance and pressure increase at PT during terminal stance due to the residuum being pushed up. Shear-to-pressure ratios were used to assess comfort, while pressure- and shear-time integrals were used to assess tissue health. We observed more notable changes at tissue sites (e.g., AD and PF). Combined evaluation of pressure and shear, including shear-to-pressure ratio and time integrals, may offer insight for residuum care.

Short partial doffs of release/relock sockets may effectively stabilize limb fluid volume in prosthesis users with transtibial amputation

BackgroundA challenge often faced by people with lower extremity amputation is management of prosthetic socket fit due to changes in fluid volume within their residual limb. Prior research suggests that intermittently doffing the prosthetic socket may help stabilize daily residual limb fluid volume. MethodsTo assess the effects of partial doff duration on residual limb fluid volume retention, participants with transtibial amputation were tested by walking on a treadmill in a controlled, laboratory setting under three conditions. An automated system to release the locking pin and enlarge the socket was used to produce the partial doffing. Percent limb fluid volume changes after partial doffing for 4 min (Short Rest) and for 10 min (Long Rest) were compared with no partial doffing (No Release). Limb fluid volume was monitored using bioimpedance analysis. FindingsMean percent fluid volume changes in the posterior region were ‐1.2% for No Release, 2.7% for Short Rest, and 1.0% for Long Rest. Short and Long Rests had larger increases than No Release (P = 0.005 and 0.03, respectively); Short and Long Rests were not statistically different (P = 0.10). Eight of the thirteen participants experienced a higher percent fluid volume gain for both release protocols while four experienced a higher percent fluid volume gain for only one release protocol. InterpretationA partial doff duration as short as 4 min may be an effective strategy to stabilize limb fluid volume in prosthesis users with transtibial amputation. Trials in at-home settings should be pursued.

Custom Silicone Distal Cup Designed and Fabricated Using 3D Optical Scanning and Additive Manufacturing to Improve Socket Fit of an Individual with Tranfemoral Amputation with Irregular Distal Residual Limb Morphology

ABSTRACT Introduction The study presents the design and manufacturing of a custom silicone distal cup, with a high spatial resolution, to fit inside the prosthetic liner for the treatment of irregular morphology at the distal residual limb of a patient with lower-limb amputation. This distal cup for the inside of the prosthetic liner has intricate interior features matching the shape of the distal residual limb to prevent localized high-pressure regions. Methods High-resolution 3D optical scanning, computer-aided design (CAD), and material extrusion (MEX) process for additive manufacturing of molds are three key techniques for designing and manufacturing this custom distal cup. A three-part mold for molding the distal cup with matching features was designed by CAD and fabricated by MEX. The subject evaluated the distal cup by walking using the distal cup before wearing the prosthetic liner in the lower-limb prosthesis. Results A custom silicone distal cup was fabricated using a 3D-printed mold and evaluated using a Prosthetic User’s Survey. Based on the survey, the insert has an acceptable comfort, suspension requirement, and ease of use. Conclusions The scan by high spatial resolution Space Spider optical scanner could capture detailed features of the distal residual limb. The resulting distal cup had the protrusion that functioned to separate the invaginations. The subject was satisfied with the distal cup based on the Prosthetic User’s Survey. Clinical Relevance The approach to fabricate the custom silicone distal cup using a high-resolution 3D optical scanner and a 3D-printed mold can be applied to fabricate the distal cup with intricate features for a patient with irregular morphology at the distal residual limbs.

Fabricating Sockets With Distance Sensors for Monitoring Prosthesis Use and Socket Fit

ABSTRACT Introduction In previous research, we developed and implemented novel inductive sensors to detect the motion of a prosthesis user’s residual limb in the prosthetic socket. Materials and Methods In this article, methods for installing the inductive sensors within the wall of a prosthetic socket are described. The sensors are flexible, 32 mm in diameter, and less than 0.2 mm thick. Two sensor placement configurations are described, one to monitor prosthesis use and the other to monitor socket fit. Results The sensors are installed after the inner resin layer of the socket is completed. Installation of the sensors increases the fabrication time over that of a traditional laminated socket by about 6 hours. Conclusions A systematic and repeatable method for manufacturing prosthetic sockets with embedded distance sensors was developed to facilitate adoption of this technique. Clinical Relevance Dissemination of the fabrication technique to install inductive distance sensors in sockets may facilitate clinical research investigation using this new technology, ultimately improving decision making for treatment, diagnosis, and prognosis of health issues faced by people with lower-limb amputation.

Validation of a Custom Interface Pressure Measurement System to Improve Fitting of Transtibial Prosthetic Check Sockets.

Achievement of fit between the residual limb and prosthetic socket during socket manufacture is a priority for clinicians and is essential for safety. Clinicians have recognised the potential benefits of having a sensor system that can provide objective socket-limb interface pressure measurements during socket fitting, but the cost of existing systems makes current technology prohibitive. This study will report on the characterisation, validation and preliminary clinical implementation of a low cost, portable, wireless sensor system designed for use during socket manufacture. Characterisation and benchtop testing demonstrated acceptable accuracy, behaviour at variable temperature, and dynamic response for use in prosthetic socket applications. Our sensor system was validated with simultaneous measurement by a commercial sensor system in the sockets of three transtibial prosthesis users during a fitting session in the clinic. There were no statistically significant differences between the sensor system and the commercial sensor for a variety of functional activities. The sensor system was found to be valid in this clinical context. Future work should explore how pressure data relates to ratings of fit and comfort, and how objective pressure data might be used to assist in clinical decision making.

Development of a prosthetic fit and alignment assessment (ProFit) in persons with post-traumatic transtibial amputation.

There are no standards for reliably measuring the quality of prosthetic fit and alignment which is important for evaluation and improvement of clinical care for patients with transtibial amputation. The purpose of this study was to develop an instrument to quantitatively assess prosthetic fit and alignment in patients with transtibial amputation. Prospective cohort study. The fit and alignment assessment (ProFit) included 39 items for assessments of skin quality, stance and gait, and radiographic characteristics that could be feasibly captured in clinic using photographs, video, and radiographs. Data were collected on adults aged 18-60 years treated with transtibial amputation and followed up for 18 months at 1 of 27 US hospitals. One hundred thirteen assessments were conducted by 6 prosthetists using an online platform. Items demonstrating reliability and face validity were included in the ProFit score for subsequent validation testing. Validation measures included 18-month patient-reported function (Short Musculoskeletal Function Assessment ), tests of physical performance, patient-reported pain (Brief Pain Inventory ), satisfaction with prosthesis (Orthotics Prosthetics Users Survey), prosthesis use, and walking activity. The ProFit score included 10 of 39 items that demonstrated high inter-rater reliability and face validity. A higher ProFit score correlated with worse function on all domains of the Short Musculoskeletal Function Assessment except arm and hand and with worse performance on the 4-Square Step Test, Shuttle Run, and Illinois Agility Test. ProFit scores did not correlate with the Brief Pain Inventory, Orthotics Prosthetics Users Survey, prosthesis use, or walking activity. The ProFit score can be used by researchers and clinicians to measure the quality of socket fit and prosthetic alignment. Future prospective validation is necessary to verify the promising results observed in ProFit development and establish clinical utility.