Prosthesis Design Research Articles

Design and Mechanical Characterization of a Variable Stiffness ESR Foot Prosthesis

Design and Mechanical Characterization of a Variable Stiffness ESR Foot Prosthesis

A robotic emulator for the systematic exploration of transtibial biarticular prosthesis designs.

People with transtibial limb loss frequently experience suboptimal gait outcomes. This is partly attributable to the absence of the biarticular gastrocnemius muscle, which plays a unique role in walking. Although a recent surge of biarticular prostheses aims to restore gastrocnemius function, the broad design space and lack of consensus on optimal hardware and control strategies present scientific and engineering challenges. This study introduces a robotic biarticular prosthesis emulator, comprising a uniarticular ankle-foot prosthesis and knee flexion exoskeleton, each actuated by a custom off-board system. Benchtop experiments were conducted to characterize the emulator's mechatronic performance. Walking experiments with one transtibial amputee demonstrated the system's capability to provide knee and ankle assistance. The -3dB bandwidths for the knee exoskeleton's torque and motor velocity controllers were measured at approximately 5Hz and 100Hz, respectively. A feedforward iterative learning controller reduced the root-mean-squared torque tracking error from 6.04Nm to 0.99Nm in hardware-in-the-loop experiments, an 84% improvement. User-preference-based tuning yielded a peak knee torque of approximately 20% of the estimated biological knee moment. This biarticular prosthesis emulator demonstrates significant potential as a versatile research platform that can offer valuable insights for the advancement of lower-limb assistive devices.

Toward the Development of User-Centered Neurointegrated Lower Limb Prostheses.

The last few years witnessed radical improvements in lower-limb prostheses. Researchers have presented innovative solutions to overcome the limits of the first generation of prostheses, refining specific aspects which could be implemented in future prostheses designs. Each aspect of lower-limb prostheses has been upgraded, but despite these advances, a number of deficiencies remain and the most capable limb prostheses fall far short of the capabilities of the healthy limb. This article describes the current state of prosthesis technology; identifies a number of deficiencies across the spectrum of lower limb prosthetic components with respect to users' needs; and discusses research opportunities in design and control that would substantially improve functionality concerning each deficiency. In doing so, the authors present a roadmap of patients related issues that should be addressed in order to fulfill the vision of a next-generation, neurally-integrated, highly-functional lower limb prosthesis.

Investigating the performance of soft robotic adaptive feet with longitudinal and transverse arches.

Biped robots usually adopt feet with a rigid structure that simplifies walking on flat grounds and yet hinders ground adaptation in unstructured environments, thus jeopardizing stability. We recently explored in the SoftFoot the idea of adapting a robotic foot to ground irregularities along the sagittal plane. Building on the previous results, we propose in this paper a novel robotic foot able to adapt both in the sagittal and frontal planes, similarly to the human foot. It features five parallel modules with intrinsic longitudinal adaptability that can be combined in many possible designs through optional rigid or elastic connections. By following a methodological design approach, we narrow down the design space to five candidate foot designs and implement them on a modular system. Prototypes are tested experimentally via controlled application of force, through a robotic arm, onto a sensorized plate endowed with different obstacles. Their performance is compared, using also a rigid foot and the previous SoftFoot as a baseline. Analysis of footprint stability shows that the introduction of the transverse arch, by elastically connecting the five parallel modules, is advantageous for obstacle negotiation, especially when obstacles are located under the forefoot. In addition to biped robots' locomotion, this finding might also benefit lower-limb prostheses design.

Improved postoperative kneeling ability in posterior stabilized total knee arthroplasty with medialized dome-patella resurfacing: A retrospective comparative outcome analysis

ObjectivesThis investigation aimed to evaluate if the modifications to prosthesis designs improve patients' clinical and functional outcomes after total knee arthroplasty (TKA), with a special focus on pain and kneeling ability. MethodsRetrospective and comparative analysis of consecutive patients who were treated with posterior stabilized TKA using two different prostheses designs (single surgeon, single vendor). Group 1 received a traditional design TKA (PFC Sigma; DePuy, Inc., Warsaw, IN) with conventional dome-patella resurfacing, and group 2 received a modern design implant (Attune; DePuy, Inc., Warsaw, IN) with medialized dome-patella resurfacing. Functional outcome (range of motion: ROM) and the Oxford Knee Score (OKS) were collected preoperatively, at 4–6 weeks and 12 months following surgery. ResultsNinety-nine participants were included. Of these, 30 received traditional-design implants and 69 received modern-design knee implants. The comparison between the two implants showed a statistically significant increase in total OKS and kneeling ability in the modern design cohort at 1-year follow-up compared to the traditional design cohort (p ​< ​0.01). In the modern design group, 53% (N ​= ​37) could kneel easily or with little difficulty, compared to 30% (N ​= ​9) in the traditional design group. No statistically significant differences in ROM or the OKS pain component were seen. ConclusionThe incorporation of a medialized dome-patella in modern knee implant design may offer advantages over traditional designs, as seen in improved total OKS and kneeling ability at one-year follow-up. Further research with larger cohorts is needed to confirm these findings and explore the broader impact of implant design changes on patient outcomes. Level of evidenceClinical Study, Level III.

Three-dimensional reconstruction of femur based on Laplace operator and statistical shape model

Reconstructing three-dimensional (3D) models from two-dimensional (2D) images is necessary for preoperative planning and the customization of joint prostheses. However, the traditional statistical modeling reconstruction shows a low accuracy due to limited 3D characteristics and information loss. In this study, we proposed a new method to reconstruct the 3D models of femoral images by combining a statistical shape model with Laplacian surface deformation, which greatly improved the accuracy of the reconstruction. In this method, a Laplace operator was introduced to represent the 3D model derived from the statistical shape model. By coordinate transformations in the Laplacian system, novel skeletal features were established and the model was accurately aligned with its 2D image. Finally, 50 femoral models were utilized to verify the effectiveness of this method. The results indicated that the precision of the method was improved by 16.8%-25.9% compared with the traditional statistical shape model reconstruction. Therefore, the method we proposed allows a more accurate 3D bone reconstruction, which facilitates the development of personalized prosthesis design, precise positioning, and quick biomechanical analysis.

Distal weight bearing in transtibial prosthesis users wearing pin suspension.

Low-level distal weight bearing in transtibial prosthesis users may help maintain perfusion and improve both proprioception and residual limb tissue health. The primary objectives of this research were to develop a sensor to continuously measure distal weight bearing, evaluate how prosthesis design variables affected weight bearing levels, and assess fluctuations in distal weight bearing during at-home and community use. In-lab testing on a small group of participants wearing adjustable sockets demonstrated that if distal contact was present, when socket size was increased distal weight bearing increased and when socket size was reduced distal weight bearing decreased. During take-home use, participants accepted the distal weight bearing level set by the research team. It ranged between 1.1% and 6.4% BW for all days tested. The coefficient of variation (standard deviation/mean) ranged from 25% to 43% and was expected due in part to differences in walking style, speed, terrain, direction of ambulation, and bout duration. Two participants commented that they preferred presence of distal weight bearing to non-presence. Next steps in this research are to develop clinical practices to determine target distal weight bearing levels and ranges, and to simplify the design of the sensor and weight bearing adjustment mechanism for clinical use.

Non-Invasive Sensory Input Results in Changes in Non-Painful and Painful Sensations in Two Upper-Limb Amputees

Designs of active prostheses attempt to compensate for various functional losses following amputation. Integration of sensory feedback with the functional control re-enables sensory interaction with the environment through the prosthetic. Besides the functional and sensory loss, amputation induces anatomical and physiological changes of the sensory neural pathways, both peripherally and centrally, which can lead to phantom limb pain (PLP). Additionally, referred sensation areas (RSAs) likely originating from peripheral nerve sprouting, regeneration, and sensory reinnervation may develop. RSAs might provide a non-invasive access point to sensory neural pathways that project to the lost limb. This paper aims to report on the sensory input features, elicited using non-invasive electrical stimulation of RSAs that over time alleviated PLP in two upper-limb amputees. The distinct features of RSAs and sensation evoked using mechanical and electrical stimuli were characterized for the two participants over a period of 7 and 9 weeks, respectively. Both participants received transradial and transhumeral amputation following traumatic injuries. In one participant, a relatively low but stable number of RSAs provided a large variety of types of evoked phantom hand (PH) sensations. These included non-painful touch, vibration, tingling, stabbing, pressure, warmth/cold as well as the perception of various positions and movements of the phantom hand upon stimulation. Discomforting and painful sensations were induced with both mechanical and electrical stimuli. The other participant had a relatively large number of RSAs which varied over time. Stimulation of the RSAs provided mostly non-painful sensations of touch in the phantom hand. Temporary PLP alleviation and a change in the perception of the phantom hand from a tight to a more open fist were reported by both participants. The specificity of RSAs, dynamics in perception of the sensory input, and the associated alleviation of PLP could be effectively exploited by designs of future active prostheses. As such, techniques for the modulation of the sensory input associated with paradigms from interaction with the environment may add another dimension of protheses towards integrating personalized therapy for PLP.

Results of a study of zinc-phosphate cements for fixation of fixed orthopedic structures under the influence of material hardening time

Patients often prefer non-removable prosthesis designs to replace dental row defects, given their undeniable benefits. However, there is a possibility of developing complications during prosthetics, it is impossible to completely exclude medical errors and errors of the dental technician.&#x0D; Dentists know that in 20% of cases, prosthetics with non-removable types of prostheses end unsuccessfully due to errors in treatment, as well as improper use of fixing cements at the stage of storing the prosthesis. About 20% of cases are complications in the near future after prosthetics during the operation of the prosthesis. The proportion of complications due to carious tooth damage under prostheses can reach more than 49%.&#x0D; Non-removable prostheses, firmly fixed by zinc-phosphate cements, gain a number of advantages by choosing this particular material: a slight percentage of shrinkage; low percent solubility; increased strength; creation of a holding layer between tissues of the oral cavity and a selected type of prosthesis.&#x0D; Our study is devoted to the issues of assessing the most significant qualities of fixing cements, which is of great practical importance.

Application of 3D digital smile design based on virtual articulation analysis in esthetic dentistry: A technique

A technique for the application of a virtual articulation system in 3-dimensional digital smile design (DSD) during esthetic restoration is described. To acquire stable occlusion and a smooth jaw movement pattern without premature contacts or interference, a digital facebow and a virtual articulator were used to collect and analyze a patient’s occlusal data and jaw movement information. The original pattern of occlusal contacts and jaw movements were diagnosed as stable and copied to the digital design of the new prostheses. Preparation of the abutments, crown lengthening surgery, and definitive crown fabrication and cementation were performed according to the design. After 9 months, the occlusion remained stable, and the patient was satisfied with the outcome.

Design of 3D-printed prostheses for reconstruction of periacetabular bone tumors using topology optimization.

Background: Prostheses for the reconstruction of periacetabular bone tumors are prone to instigate stress shielding. The purpose of this study is to design 3D-printed prostheses with topology optimization (TO) for the reconstruction of periacetabular bone tumors and to add porous structures to reduce stress shielding and facilitate integration between prostheses and host bone. Methods: Utilizing patient CT data, we constructed a finite element analysis (FEA) model. Subsequent phases encompassed carrying out TO on the designated area, utilizing the solid isotropic material penalization model (SIMP), and this optimized removal area was replaced with a porous structure. Further analyses included preoperative FEA simulations to comparatively evaluate parameters, including maximum stress, stress distribution, strain energy density (SED), and the relative micromotion of prostheses before and after TO. Furthermore, FEA based on patients' postoperative CT data was conducted again to assess the potential risk of stress shielding subsequent to implantation. Ultimately, preliminary follow-up findings from two patients were documented. Results: In both prostheses, the SED before and after TO increased by 143.61% (from 0.10322 to 0.25145mJ/mm3) and 35.050% (from 0.30964 to 0.41817mJ/mm3) respectively, showing significant differences (p < 0.001). The peak stress in the Type II prosthesis decreased by 10.494% (from 77.227 to 69.123MPa), while there was no significant change in peak stress for the Type I prosthesis. There were no significant changes in stress distribution or the proportion of regions with micromotion less than 28μm before and after TO for either prosthesis. Postoperative FEA verified results showed that the stress in the pelvis and prostheses remained at relatively low levels. The results of follow-up showed that the patients had successful osseointegration and their MSTS scores at the 12thmonth after surgery were both 100%. Conclusion: These two types of 3D-printed porous prostheses using TO for periacetabular bone tumor reconstruction offer advantages over traditional prostheses by reducing stress shielding and promoting osseointegration, while maintaining the original stiffness of the prosthesis. Furthermore, in vivo experiments show that these prostheses meet the requirements for daily activities of patients. This study provides a valuable reference for the design of future periacetabular bone tumor reconstruction prostheses.

Finite Element Analysis (FEA) for the Evaluation of Retention in a Conometric Connection for Implant and Prosthesis

Today, dental implantology represents a reliable technique for treating both partial and total edentulism. The fixation of dentures on dental implants can be achieved using various techniques, where the choice of a specific technique depends on the patient’s individual needs, the jawbone’s condition, and the prosthesis design. Currently, the two most common types of prosthetic abutment connections are cemented and screwed, each with its own set of advantages and disadvantages. This study aimed to analyze a novel Morse cone connection system between the prosthesis and implant using finite element analysis (FEA). The analysis of connection retention was conducted using three different approaches: analytical, in vitro, and FEA. Three-dimensional models were created for systems comprising an abutment, healing cap, and crown under three inclination conditions: 0°, 15°, and 30°. Using Ansys finite element software (R1 2023), the impact of the tilt on the system retention was examined. The FEA showed results comparable with the in vitro studies regarding the retention strength for an abutment cap system with a 4° taper, obtaining 66.6 N compared with the 68 N calculated in our in vitro study. The inclination of the abutment affected the system retention due to the hole made in the abutment’s surface, decreasing the contact area between components. The Morse cone prosthesis–implant connection system was found to be the most stable and efficient compared with threaded or cemented systems. The retention was influenced by factors such as the abutment conicity, insertion strength, and the contact surface between components.

The effects of length and width of the stem on proximal humerus stress shielding in uncemented primary reverse total shoulder arthroplasty.

To preserve humeral bone during RTSA, stems have been made shorter and cement avoided whenever possible. However, with the increased use of uncemented RTSA, a phenomenon comparable to the stress shielding of the hip has been described for the proximal humerus. The aim of this study was to investigate the influence of stem length and width on proximal humeral bone resorption after primary uncemented RTSA. The prospective shoulder arthroplasty database of our institution was reviewed for all primary uncemented RTSAs from 2017 to 2020 in osteoarthritis and cuff tear arthropathy cases with > 2-year follow-up. We compared the clinical and the radiographic 2-year outcome of the short and standard length stems of the same prosthesis design. This allowed us to assess the effects of stem length and width with regard to stress shielding. Furthermore, we defined a cut-off value for the filling ratios to prevent stress shielding. Fifty patients were included in the analysis, nineteen were in the short stem group (SHORT) and thirty-one in the standard stem group (STANDARD). After 2years, SHORT showed a relative Constant Score of 91.8% and STANDARD of 98.3% (p = 0.256). Stress shielding was found in 4 patients (21%) in SHORT and in 16 patients (52%) in STANDARD (p = 0.03); it occurred more frequently in patients with higher humeral filling ratios (p < 0.05). The calculated cut-off to prevent stress shielding was 0.7 (± 0.03) for the metaphyseal and distal filling ratio. While short and standard stems for RTSA have good results after 2years, we found a significant negative effect of higher length and width of the stem with regard to stress shielding. Even though the clinical effects of stress shielding have to be assessed, short stems should be chosen with a filling ratio at the metaphyseal and distal position below 0.7. III.

Reliability and Validity Testing of the Persian Version of the Derriford Appearance Scale 24 in a Sample of Individuals with Craniofacial Irregularity and Amputation.

Despite the recent advancements in the design and manufacture of prostheses for individuals with craniofacial irregularity and amputation, these individuals tend to become self-conscious about their appearance. The aim of this study was to investigate the reliability and validity of Persian version of the Derriford Appearance Scale24 (P-DAS24) for a sample of individuals with craniofacial irregularity and limb loss. Reliability of the P-DAS24 was determined by computing internal consistency and test-retest reliability utilizing Cronbach's alpha coefficient and Pearson's correlation coefficient. Discriminant validity was investigated with comparing the total score of the P-DAS24 between disfigured participants and those with no appearance problem. Known-groups validity was evaluated regarding the participants' gender and their level of involvement. The sample size comprised of 251 individuals with disfigurement and 101 without disfigurement who were deemed normal in appearance. The P-DAS24 showed satisfactory internal consistency (Cronbach's alpha = 0.89) and excellent test-retest reliability (r = 0.96). The total score of the P-DAS24 showed a statistically significant difference between individuals deemed disfigured or normal (P=0.01). The total scores P-DAS24 in individuals with different levels of involvement were significantly different (P<0.001). The scores of the DAS2, DAS18, DAS21, and DAS24 were significantly different between men and women (P<0.01, <0.01, 0.03, and 0.01, respectively). The P-DAS24 is a valid and reliable tool that may be utilized in clinical practice and researches to assess the outcomes of prosthetic reconstructions in individuals with disfigurement.

Outcomes of isolated patellofemoral arthroplasty

Osteoarthritis of the patellofemoral compartment can cause significant functional impairment. Isolated patellofemoral osteoarthritis affects greater than 10% of males and females over the age of 60. Patellofemoral arthroplasty (PFA) was developed as a joint-preserving procedure that maintains natural knee kinematics in those with isolated patellofemoral disease. First-generation implants were fraught with complications, a high rate of revision, and early conversion to total knee arthroplasty (TKA). Second-generation implants have demonstrated significant improvements in patient-reported outcome measures, complication rates and implant survivorship. Factors that can affect outcomes include surgical indications, patient selection, and PFA prosthesis design. Modern PFA for isolated patellofemoral osteoarthritis has comparable outcomes to TKA for isolated patellofemoral osteoarthritis. In this article, we discuss the use of PFA, implant design, the indications and factors affecting outcomes, and comparison to TKA.

Development of Customized Passive Arm Prosthetics by Integrating 3D Printing and Scanning Technology

Severe hand injuries resulting from accidents can lead to the traumatic loss of an upper limb. The provision of an assistive device, such as an arm prosthesis, can help patients regain their courage and motivation to engage with the public. This project aimed to integrate 3D scanning and printing technology to develop a customized passive arm prosthesis for individuals who have experienced shoulder disarticulation due to a traumatic accident. The fabrication of the arm prosthesis was specifically designed and tailored to meet each patient’s unique needs and preferences. The prosthesis design was created based on 3D scan files obtained from the patients. Finite element analysis was employed to analyze the design and determine the optimal materials to use, as well as to optimize the overall design. The finalized model was then converted into STL file format and G-code for the 3D printing process. To ensure ease of use, the entire arm prosthesis and a harness system were assembled, and multiple tests and fittings were conducted on the patient. Several prototypes of the arm prosthesis were fabricated to achieve the best fit for each individual patient.

Restoratively driven planning for implants in the posterior maxilla - Part 2: implant planning, biomechanics and prosthodontic planning a proposed prosthodontic complexity index

Restoratively driven implant planning in the posterior maxilla requires a comprehensive understanding of the anatomical and physiological changes of the alveolar bone following tooth extraction and sinus augmentation. As a part of restoratively driven planning, alveolar bone, inter-arch relationships, proposed crown-implant ratio and anticipated non-axial loading should be assessed pre-operatively. This helps determine the prosthodontic and surgical aspects of implant treatment, such as prosthesis design, implant number, implant angulation, implant length and the necessity for additional bone grafting procedures. However, currently no implant planning classification is restoratively driven and include these important prosthodontic considerations. Therefore, a new index - the Posterior Maxilla Prosthodontic Index - is defined to encourage restoratively driven implant planning in the posterior maxilla.

Design and control of active lower limb prosthesis with sensorial frame

In this article, we have designed an active prosthesis for the lower limb of a human. The unique design incorporates an exoskeletal extension that serves as a low-cost sensory framework, providing feedback on residual signals, namely the states of the hip and thigh. The controller takes advantage of system modeling and employs a simple proportional–derivative control. A stability analysis has been conducted. We have also provided simulations and analysis of the active prosthesis to evaluate the effectiveness of the design and control.

Clinical Outcomes and Complications of 2-Stage Septic Versus Aseptic Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Although several studies have compared the clinical outcomes of septic and aseptic revision total knee arthroplasty (TKA), their results have been controversial. Therefore, this study aimed to compare clinical outcomes and complications of septic and aseptic revision TKA through a systematic review and meta-analysis. The PubMed (MEDLINE) and Embase databases were searched for studies evaluating the clinical outcomes and complications of 2-stage septic revision and aseptic revision TKAs. A systematic review of clinical outcomes (Knee Society Knee and Function Scores and range of motion) and complications (reoperation, infection, and failure rates) was conducted. Thirteen studies were included in the systematic review. The mean MINORS (Methodological Index for NOn-Randomized Studies) score of the included studies was 20.5 (range, 18 to 22). The meta-analysis revealed higher reoperation (risk ratio [RR], 1.98; 95% confidence interval [CI], 1.50 to 2.62; p < 0.00001), infection (RR, 4.08; 95% CI, 2.94 to 5.64; p < 0.00001), and failure rates (RR, 2.88; 95% CI, 1.38 to 6.03; p = 0.005) in septic revision TKAs than in aseptic revision TKAs. Moreover, septic revision TKAs showed lower Knee Society Knee Scores compared with aseptic TKAs (mean difference [MD], -6.86; 95% CI, -11.80 to -1.92; p = 0.006). However, the Knee Society Function Score (MD, -1.84; 95% CI, -7.84 to 3.80; p = 0.52) and range of motion (MD, -6.96°; 95% CI, -16.23° to 2.31°; p = 0.14) were not significantly different between septic and aseptic revision TKAs. Despite the heterogeneity of prosthesis designs and surgical protocols used in septic and aseptic revision TKAs, the results of this systematic review suggest that 2-stage septic revision TKAs have poorer clinical outcomes and higher complication rates than aseptic revision TKAs do. Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Establishing Baseline Radiological Metrics of the Talus and Calcaneus: A Retrospective Analysis of Computed Tomography Imaging in an Irish Cohort.

Introduction The subtalar joint anatomy is complex and heterogeneity in its morphology creates unique challenges for foot and ankle surgeons. Anatomical metrics used for prosthesis design are well established. However, there is a paucity of literature quantifying foot and ankle measurement techniques and metrics used for prosthesis design. The aim of this study was to documentreproducible measurement techniques and quantify talar and calcaneal metrics in a sample of Irish patients on computed tomography imaging to aid in the design of a novel hindfoot plate. Methods A retrospective analysis of consecutive foot and ankle computed tomography images performed at our institution was undertaken. Five measurements were performed on each foot and ankle image. Statistical analysis was performed to identify if a correlation existed between measurements. Results Sixty-four CTs met the inclusion criteria. Talar body height 27.1 mm (SD 2.17 mm), talar neck width 32.7 mm (3.16 mm), talar head height 25.41 (SD 2.16 mm), lateral process to posterior talus 23.6 (2.64 mm), calcaneal height 43.8 mm (SD 3.9 mm). A positive correlation was identified between all measurements. Conclusion This study identified that there was a low degree of heterogeneity in talar and calcaneal measurements in an Irish cohort. Furthermore, the metrics used in this study will provide valuable information for the preliminary design of a novel hindfoot plate.