Prosthesis Design Research Articles

Mid-term clinical outcomes of a posterior stabilized total knee prosthesis for Japanese patients: A minimum follow-up of 5 years

BackgroundA high–flexion posterior-stabilized total knee prosthesis has been developed for the Asian population. The component design was based on computed tomography images of Japanese osteoarthritic knees. The femoral component is composed of zirconia ceramics, which exhibit low friction and high durability. The present study aimed to evaluate the mid-term clinical outcomes of this implant. MethodsThis study included 334 knees of 210 patients who underwent primary total knee arthroplasty with this implant at our hospital between October 2010 and December 2014. The patients comprised 28 men and 172 women with an average age of 73 years. The average follow-up period was 5.9 years, and the follow-up rate was 71.1%. Clinical outcomes were assessed using the Knee Society scoring system, 2011 Knee Society questionnaire, and Knee Injury and Osteoarthritis Outcome Score. Kaplan–Meier survivorship analysis was performed to determine the cumulative prosthesis survival rate. ResultsIn terms of clinical outcomes at the final follow-up, the average ranges of motion were −2.0 in extension and 126.7 in flexion. The Knee Society knee and function scores were 94.2% and 72.6%, respectively. With revision surgery or radiographic failure for any reason as the endpoint, the survival rates at 5 and 9 years were 98.2% and 95.5%, respectively. The most common reason for revision surgery or radiological failure was aseptic loosening. ConclusionsDespite several revision cases mainly due to aseptic loosening, the present study found that this new high-flexion posterior-stabilized total knee arthroplasty prosthesis design showed comparable results for Asian populations with other PS prosthesis. Levels of evidenceLevel Ⅱ (Prospective cohort study).

Influencia de las prótesis inversas con diseño lateralizado en la consolidación de las tuberosidades en fracturas de húmero proximal

IntroductionProximal humerus fractures are the third most frequent type of fracture in elderly patients. Nowadays, surgical treatment is indicated one third of the time, being the reverse shoulder prosthesis an option especially in complex comminuted patterns. In this study we analyzed the effects of a lateralized reverse prosthesis in tuberosity union and its relationship with the functional results. Material and methodsRetrospective case study of patients with proximal humerus fractures treated with a lateralized design reverse shoulder prosthesis with one-year minimum follow-up. Tuberosity nonunion was defined as a radiological concept: absence of tuberosity, distance>1cm from the tuberosity fragment to the humeral shaft or tuberosity above the humeral tray. Subgroup analysis was performed, group 1 (n=16) tuberosity union vs. group 2 (n=19) tuberosity nonunion. Groups were compared with the following functional scores: Constant, American Shoulder and Elbow Surgeons and Subjective Shoulder Value. ResultsA total of 35 patients were included in this study with a median age of 72.65 years. Postoperative radiographic analysis at one year after surgery revealed a tuberosity nonunion rate of 54%. Subgroup analysis revealed no statistically significant differences in terms of range of motion or functional scores. However, there were differences regarding the Patte sign (p=0.03) which was positive in a larger proportion of patients in the group with tuberosity nonunion. ConclusionEven though there was a large percentage of tuberosity nonunion with the use of a lateralized prosthesis design, patients obtained good results in a similar manner to those found in the union group in terms of range of motion, scores, and patient satisfaction.

Low-cost prosthetic feet for underserved populations: A comparison of gait analysis and mechanical stiffness.

Lower-limb loss is an ongoing cause of disability throughout the world. Despite advancements in prosthetic technologies, there are numerous underserved populations in need of effective low-cost prosthetic foot options. To evaluate the biomechanical performance of several low-cost prosthetic feet, using a combination of instrumented gait analysis and mechanical stiffness testing. Randomized crossover with additional case study. We compared the solid-ankle-cushioned-heel (SACH), Jaipur, and Niagara feet with carbon fiber feet. Mechanical stiffness was evaluated using a cantilever-style bending test at 2 angles that was designed to mimic late stance gait loading. Eight below-knee amputees participated in the gait analysis, which focused on foot and ankle motion and energetics. Metric analysis showed significant differences among feet in ankle motion and power as well as distal-to-shank power, with SACH showing reduced ankle motion and positive work compared with the other feet. Waveform analysis additionally revealed a compensatory knee flexion moment in SACH and a knee extension moment in Niagara and Jaipur during midstance. In mechanical stiffness testing, SACH had the highest stiffness, with Niagara and carbon fiber roughly similar, and Jaipur the most compliant with the greatest hysteresis. There may be an optimal stiffness range for future prosthesis designs that maximizes propulsive energy. This may be achieved by combining some characteristics of Jaipur and Niagara feet in new designs. Ultimately, optimizing stiffness and energetics for gait biomimicry while maintaining cost, availability, and versatility across cultures will alleviate the effects of limb loss among underserved populations.

Arthroplasty in thumb trapeziometacarpal (CMC joint) osteoarthritis: An alternative to excision arthroplasty

Trapeziectomy for base of thumb arthritis is well established, but base of thumb arthroplasty offers potential advantages. The review covers the development of arthroplasty for the thumb from interposition arthroplasty to total joint replacement. It discusses contemporary prosthesis designs and results, including trapezial component geometry, bearing surfaces, and dual mobility.

Early and mid-term results with the ATTUNE total knee replacement system compared to PFC Sigma: a prospective comparative study

PurposeUp to 20% of all patients are not satisfied with the result after total knee arthroplasty (TKA). To improve patient satisfaction manufacturers have modified prosthesis design. The ATTUNE prosthesis is a modified version of the PFC Sigma. Aim of this study was to evaluate the outcome at 6 months and 5 years after TKA with ATTUNE compared to PFC Sigma.MethodsSixty patients were included prospectively (30 ATTUNE vs. 30 PFC Sigma). Knee Society Score and Hospital for Special Surgery Score were recorded preoperatively, at 6 months and at least 5 years postoperatively. At 5-years follow-up X-rays in two planes were evaluated, radiolucent lines were documented.ResultsPatient characteristics were similar in both groups. Both ATTUNE and PFC Sigma provided good to excellent clinical results. There were no statistically significant differences based on the overall scores and patient rated outcome measures. Nevertheless, patients in the ATTUNE group tended to be symptom-free earlier and to achieve better clinical results after 5 years.ConclusionEven with the scores not being significantly different here, the modified design of ATTUNE could increase long-term satisfaction with the implant and reduce the need for revision surgery. However, long-term results are required to prove this.

Advances in Penile Prosthesis Surgery: A Clinical Update.

Despite the introduction of effective oral pharmacotherapy for the treatment of erectile dysfunction (ED), penile implants are still the standard care for patients who do not respond well to medical therapy. Since the first inflatable penile implant surgery was performed almost 40 years ago, a variety of improvements in the penile prosthesis design, and advancements in material science, surgical technique, and post-operative care have been developed to increase patients' satisfaction, as well as that of their partners. Penile implants have evolved vastly during that same time frame and now represent the cutting-edge technology, durability, and function. Here, advancements are reviewed with a focus upon recent developments in surgical techniques and device technology.

Best practice in shoulder arthroplasty-a reflective personal review

IntroductionShoulder arthroplasty is uncommon but increasing in number when compared to hip and knee arthroplasty. The average UK shoulder surgeon performs less than 10 a year and revision surgery is even more rare. The surgeon should be familiar with surgical approaches, implant designs and preferably be fellowship trained to produce good outcomes. MethodsNarrative review was undertaken and senior author's personal practice was discussed. ResultsThe need for a clear understanding of indications and contraindications for both anatomic shoulder arthroplasty and reverse total shoulder arthroplasty, good preoperative planning, protocol-based peri-operative management and good rehabilitation protocol in the post operative period cannot be overemphasized. ConclusionWe are still learning best practice and prosthesis designs have changed over the past years with extensive choices especially in Reverse arthroplasty. Each of these designs has unique biomechanical properties and require a deep understanding of indications. Good surgical training and the use of multi-disciplinary team meetings for complex cases should improve the safety and quality of surgery for patients and ultimately long-term outcome of shoulder arthroplasty.

Comparison of the in-vivo kinematics of three different knee prosthesis designs during a step-up movement

BackgroundThere is no consensus on the importance of the kinematics of the prosthetic joint for the clinical outcome after total knee arthroplasty. A 3-armed randomized controlled trial was done to determine and compare the in vivo kinematics of a posterior cruciate-retaining and two posterior cruciate-sacrificing (Anterior-Stabilized and Posterior-Stabilized) prosthetic designs from the same total knee arthroplasty system. Since the anterior-stabilized and posterior-stabilized designs are posterior cruciate ligament-sacrificing designs, we hypothesized they would have similar contact-point kinematics. Further, we hypothesized that the cruciate-retaining design would have contact-point kinematics different from the anterior-stabilized and the posterior-stabilized designs, but comparable to a native knee. MethodsThirty-nine patients with a well-functioning total knee arthroplasty one year postoperatively underwent kinematic analysis of a weight-bearing step-up movement under fluoroscopic recording. Model-based radiostereometric analysis was used to determine anteroposterior contact-point translations and rotations through the movement path to assess knee kinematics. FindingsThe cruciate-retaining and anterior-stabilized groups' medial and lateral contact-points displayed similar paradoxical posterior translations during step-up in the magnitude of 7 and 2 mm, respectively. In contrast, the posterior-stabilized group's contact-points translated anteriorly by 4 and 10 mm throughout the movement and were significantly more posterior than the cruciate-retaining and the anterior-stabilized groups from >100° to 40° of flexion. The femur rotated internally with all designs. InterpretationThe cruciate-retaining and anterior-stabilized designs displayed similar contact-point translation patterns during a step-up movement. Only the posterior-stabilized design showed a pattern comparable to native knees. Conversion from a cruciate-retaining to an anterior-stabilized design because of posterior cruciate ligament insufficiency will not change knee kinematics.

Design of a S-shape middle-ear ossicular replacement prosthesis and its comparison with present-day prostheses using finite element modelling

Design of a S-shape middle-ear ossicular replacement prosthesis and its comparison with present-day prostheses using finite element modelling

Ten-year follow-up of a total knee prosthesis combining multi-radius, ultra-congruency, posterior-stabilization and mobile-bearing insert shows long-lasting clinically relevant improvements in pain, stiffness, function and stability

PurposeThere is a paucity of data available on total knee prostheses combining dual-radius, ultra-congruency, posterior-stabilization and mobile-bearing insert. This prospective cohort study aimed to assess the clinical evolution of the FIRST® prosthesis (Symbios Orthopédie, Yverdon, CH), the earliest prosthesis with this particular design. It was hypothesized that the primary outcomes, evaluating pain, stiffness, function and stability, would improve following arthroplasty and remain improved during the follow-up period of 10 years.MethodsAll patients programmed for a total knee arthroplasty using a FIRST® prosthesis at our university hospital between 2006 and 2008 were invited to participate. Study knees were evaluated pre-operatively as well as one, five and ten years post-operatively. Patients filled out questionnaires at each evaluation point and had a radiographic assessment at the five-year and ten-year follow-ups. Primary outcomes were the total, pain, stiffness and function measures of the Western Ontario and McMaster Universities Osteoarthritis questionnaire (WOMAC) and the knee and function measures of the Knee Society Score (KSS). Friedman and Wilcoxon’s rank-sum tests were used to compare measures across time points.ResultsHundred and twenty four prostheses were included (baseline demographics: 69.9 ± 8.3 years old, 28.1 ± 4.3 kg/m2, 54% male) and 68 could be followed during ten years. Five prostheses underwent a revision. All other prostheses lost at follow-up were lost for reasons unrelated to the prosthesis. All primary measures reported statistically and clinically significant improvements between baseline and the three follow-up evaluations. Statistically significant improvements at the three follow-up evaluations were also observed for most secondary measures. There was no implant loosening. At ten-year follow-up, radiolucent lines were observed in 2.9% femoral implants and 1.5% tibial implants.ConclusionThe positive results observed in all domains of assessment and the small revision rate demonstrated an effective functioning of the FIRST® prosthesis during the ten-year follow-up period. The results, globally similar to those previously published for other prosthesis designs, encourage the development of assistive methods to select the most appropriate designs on an individual basis.Level of evidenceIV, prospective cohort study.

Reverse shoulder arthroplasty using an onlay humeral prosthesis, offset humeral tray, and augmented glenoid baseplate: surgical technique and review of the impact of prosthesis design on scapular fractures following reverse shoulder arthroplasty

Reverse total shoulder arthroplasty (RSA) has become the most utilized form of arthroplasty of the shoulder. Acromial stress fractures and scapular spine stress fractures are rare, yet well-recognized complications of RSA with ongoing studies identifying whether patient factors or prosthetic designs serve as risk factors. Specifically, it remains unclear if or how the position of the humeral tray (inlay or onlay) in RSA affects rates of periscapular fractures. The purpose of this article is to describe our technique for RSA using an onlay prosthesis, a variable-offset humeral tray, and an augmented glenoid baseplate, as well as to review the published results of acromial and scapular spine fractures after RSA based on humeral implant design.

Extended Arm of Precision in Prosthodontics: Artificial Intelligence.

Dentistry based onartificial intelligence (AI) is not a myth but turning into a reality. AI has revolutionized medicine and dentistry in various ways. AI is a technology that uses machines to imitate intelligent human behavior. AI is gaining popularity worldwide because ofits significant impact and breakthrough in the field of intelligence innovation. It is a lifesaver in dentistry, particularly in the field of prosthodontics, because it aids in the design of prostheses and the fabrication of functional maxillofacial appliances. It also helps in the processes of patient documentation, diagnosis, treatment planning, and patient management, allowing oral healthcare professionals to work smarter rather than harder. While it cannot replace the work of a dentist because dentistry is not about disease diagnosis, it does involve correlation with other clinical findings and provides treatment to the patient. The integration of AI and digitization has brought a new paradigm in dentistry, with extremely promising prospects. The availability of insufficient and inaccurate data is now the only barrier to the deployment of AI. Therefore, dentists and clinicians must focus on collecting and entering authentic data into their database, which will be completely utilized for AI in dentistry shortly. This study focuses on various applications of AI in prosthodontics along with its limitations and future scope.

A Power-Capable Knee Prosthesis With Ballistic Swing-Phase

This paper proposes a new approach to the design of a power-capable prosthesis; namely, one that expands the behavioral capability of a knee prosthesis into the powered quadrants of the power plane, without sacrificing the range of capable behaviors in the passive quadrants, relative to existing passive microprocessor-controlled knee prostheses (MPKs). It is well-known that swing-phase knee motion during walking in healthy human gait results from the combination of inertial coupling between the thigh and shank, gravitational effects, and passive behavior at the knee. Motor-actuated prostheses with powered stance and swing capabilities have recently emerged, but none have been shown to provide a strictly-passive biomimetic swing-phase. This paper describes an approach that enables expansion of knee behavior into the powered quadrants of the power plane, without sacrificing the ability to provide a strictly-passive biomimetic swing-phase, or the passive stance-phase behaviors provided by passive MPKs.

State of the art of prosthesis simulators for the upper limb: A narrative review.

Research into prosthesis training and design puts a burden on the small population of people with upper-limb absence who can participate in these studies. One solution is to use a prosthetic hand simulator, which allows for attaching a hand prosthesis to an intact limb. However, whether the results of prosthesis simulator studies can be translated to people with upper-limb absence using a hand prosthesis is unclear. To review the literature on prosthetic hand simulators, provide an overview of current designs, and highlight the differences and similarities between prosthesis simulators and traditional prostheses. A Boolean combination of keywords was used to search 3 electronic databases: PubMed, Scopus and Web of Science. Relevant articles in English were selected. In total, 52 papers were included in the review, and an overview of the state of the art was presented. We identified the key differences between prosthesis simulators and traditional prostheses as the position of the terminal device and the available degrees of freedom of the arm and (prosthetic) wrist. This paper provides an overview of prosthesis simulator designs over the past 27 years and an overview of the similarities and differences between prosthesis simulators and prostheses. The literature does not provide enough evidence to establish whether the results obtained from simulator studies could be translated to prostheses. A recommendation for future simulator design is to constrain pro- and supination of the forearm of anatomically intact participants and add a prosthetic wrist that can pro- and supinate. Additional research is required to find the ideal terminal device position for a prosthesis simulator with respect to the person's hand.

Prosthetic reconstruction of a patient with an irradiated rhinectomy and upper lip resection with a maxillofacial prosthesis and removable complete dentures: A clinical report

When surgery is performed to remove aggressive cancer, the extent of the lesion commands the amount of tissue removed. The removal of extensive tissue such as crucial landmarks complicates prosthesis design. This clinical report describes the prosthetic reconstruction of a patient who underwent tumor resection of the upper lip, anterior portion of the nasal cavity, and cartilaginous portion of the nasal septum, as well as subsequent radiation therapy. The prosthetic rehabilitation consisted of magnetic attachments, eyeglasses, and silicone adhesives. The applied technique effectively covered the site of squamous cell carcinoma removal providing natural color and form.

Constitutive parameter identification of transtibial residual limb soft tissue using ultrasound indentation and shear wave elastography

Finite element analysis (FEA) can be used to evaluate applied interface pressures and internal tissue strains for computational prosthetic socket design. This type of framework requires realistic patient-specific limb geometry and constitutive properties. In recent studies, indentations and inverse FEA with MRI-derived 3D patient geometries were used for constitutive parameter identification. However, long computational times and use of specialized equipment presents challenges for clinical, deployment. In this study, we present a novel approach for constitutive parameter identification using a combination of FEA, ultrasound indentation, and shear wave elastography. Local shear modulus measurement using elastography during an ultrasound indentation experiment has particular significance for biomechanical modeling of the residual limb since there are known regional dependencies of soft tissue properties such as varying levels of scarring and atrophy. Beyond prosthesis design, this work has broader implications to the fields of muscle health and monitoring of disease progression.

Influence of neck shaft angle of humerus in prosthesis design

BackgroundA better understanding of the proximal humerus is essential for anatomical reconstruction of the glenohumeral joint during prosthetic replacement. The neck-shaft angle is critical for correct calcar screw positioning when fixing a proximal humeral fracture with a locking plate. It's essential for exact implant placement and treatment of any soft-tissue or bone pathology. Improper implants cause discomfort and post-operative complications, therefore understanding the humeral neck shaft angle is fundamental in the design and manufacturing of prostheses. This study looked into the necessity regional data of the humeral neck shaft angle (NSA) and its importance in shoulder prosthesis manufacturing. MethodThis cross-sectional investigation was conducted on 300 dry cadaveric humeri of unknown gender and age that were free of damage or deformity. The Goniometer was used to measure the neck shaft angle. The data was analysed using SPSS software. The standard deviation and mean were calculated. The statistical difference between the right and left humeri was assessed using the students' t' test. ObservationsThe NSA of the humerus was 131.265.82° on average. The NSA mean values were substantially higher on the right side. A statistically significant difference between the right and left humeri was revealed by a P value of 0.001. ConclusionSuccess of the shoulder arthroplasty demands anatomical reconstruction of the normal neck-shaft angle of the humerus. Racial variations in the morphometry of the neck-shaft angle needs to be considered in prosthesis design.

Failure Analysis of Ultra-High Molecular Weight Polyethylene Tibial Insert in Total Knee Arthroplasty.

Knee osteoarthritis is treated based on total knee arthroplasty (TKA) interventions. The most frequent failure cause identified in surgical practice is due to wear and oxidation processes of the prothesis’ tibial insert. This component is usually manufactured from ultra-high molecular weight polyethylene (UHMWPE). To estimate the clinical complications related to a specific prosthesis design, we investigated four UHMWPE tibial inserts retrieved from patients from Clinical Hospital Colentina, Bucharest, Romania. For the initial analysis of the polyethylene degradation modes, macrophotography was chosen. A light stereomicroscope was used to estimate the structural performance and the implant surface degradation. Scanning electron microscopy confirmed the optical results and fulfilled the computation of the Hood index. The oxidation process in UHMWPE was analyzed based on Fourier-transform infrared spectroscopy (FTIR). The crystallinity degree and the oxidation index were computed in good agreement with the existing standards. Mechanical characterization was conducted based on the small punch test. The elastic modulus, initial peak load, ultimate load, and ultimate displacement were estimated. Based on the aforementioned experimental tests, a variation between 9 and 32 was found in the case of the Hood score. The oxidation index has a value of 1.33 for the reference sample and a maximum of 9.78 for a retrieved sample.

A mixed integer linear programming framework for improving cortical vision prosthesis designs

Although cortical vision prosthesis design has been an active area of research since the early 70s, progress in performance remains quite limited. This paper aims to develop a rigorous mathematical framework, based on mixed integer programming, for the analysis of the cortical vision prosthesis design problem and the optimal estimation of a prosthesis setup parameters. The simulated examples illustrate the unique capabilities of the proposed strategy in testing the feasibility of the goals of a prosthesis under a set of specified design constraints. Investigation of the results of the simulated examples suggest that a number of electrodes much larger than the number of cortical locations that are to be controlled is needed to achieve an improved vision experience, approaching the quality of normal vision (to reach a 300 pixels/inch resolution a million-electrode implantation is required). Thus, future research should focus on how these electrodes can be safely implanted. Once this is possible, the proposed framework can be applied to decide their optimal locations and excitation currents.

Designing a 3D virtual test platform for evaluating prosthetic knee joint performance during the walking cycle

AbstractThis article introduced a three-dimension CAD model of a prosthesis testing platform using SolidWorks software to conduct a kinematic and dynamic analysis of the transfemoral prosthesis of the virtual model. Concurrently, the event-based motion simulation (EBMS) procedure was carried out on the CAD model. The concept of the operational strategy of the test platform was clarified through the machine’s real-life experience before being constructedin vitro. The platform model is capable of reproducing two active movements to simulate the locomotion of the thigh angle and hip vertical displacement for assessing the artificial knee angle motion during the gait cycle. These motions were controlled by two rotary forces (motors) that are utilized to implement control actions in EBMS. The prosthetic knee joint was built with a single axis that performs flexion and extension via the axial force of the spring. The simulation results of the thigh angle motion ranged from20°2{0}^{^\circ }to−15°-1{5}^{^\circ }, while the maximum flexion of the prosthetic knee joint was (46°4{6}^{^\circ }). The mean absolute error was (2.727°2.72{7}^{^\circ }) and (8.338°8.33{8}^{^\circ }) for the thigh and knee joints, respectively. In conclusion, the findings can be utilized to facilitate the design and development of prostheses.