Ankle Prosthesis Research Articles

Material selection for biomedical application in additive manufacturing using TOPSIS approach

In ortho-prosthetic industries, the latest development of rapid prototyping is introduced, specifically process of manufacturing orthopedic assistive devices is analysed its use has been widely expanded in orthopaedic operation. These tools are used for correct posture or movement (orthotics) or to auxiliary part of respective shape (prosthetics) while maintaining function. The production of customized base or ankle prostheses still depend on the unhurried and laborious stages of outdated plaster model making technology. Additive manufacturing technology in which three-dimensional substances can be directly created based on data computer-aided-design of layered objects to manufacture new and modified medical equipment. The motive of this paper is to search out the materials for biomedical application and then prioritize the suitable materials by TOPSIS (technique for order performance by similarity to ideal solution) approach. This approach will provide the rank of the suitable materials, which fit for biomedical products or device. Clinical trials were conducted on the prosthesis, or it was successful in terms of wearing practice, looks (colour), and adoption of materials and technology.

The INBONE-2 Total Ankle Prosthesis: Outcomes At 5 to 9 Years Follow-Up

Category:Ankle; Hindfoot; OtherIntroduction/Purpose:Short and medium term outcomes of the INBONE I and INBONE II tibial stems have been favorable. The INBONE-2 talus has been shown to have lower reoperation and failure rates compared to its predecessor, INBONE-1 at short term follow-up. The purpose of the present study was to assess mid-term outcomes for the INBONE-2 prosthesis at 5 to 9 years follow-up considering both the tibial and talar components.Methods:All patients who underwent primary total ankle arthroplasty (TAA) with INBONE-2 between July 2010 and July 2014 at a single institution and who were at least 5 years postoperative were included. A total of 15 ankles with a mean follow up 85 (range, 61-113) months met the criteria. Radiographs were assessed using coronal and sagittal alignment parameters preoperatively, at 6 weeks postoperative, and at the most recent follow-up. Medical records were reviewed and revisions, reoperations, and complications were classified according to the criteria established by Vander Griend et al. and Glazebrook at el., respectively.Results:Survivorship for the INBONE-2 at a mean of 85 months was 93.7%. Coronal and sagittal tibiotalar alignment improved after surgery (p=0.081, p=0.15), and was maintained at the most recent follow-up (p=0.684, p=0.837). One ankle (6.7%) required early component revision; while 4 (26.7%) required a non-implant related revision. Six complications (2 high grade, 1 intermediate, and 3 low) in 5 ankles (33.3%) were recorded according to the Glazebrook classification system.Conclusion:The present study is the first to report midterm follow-up after TAA with the INBONE-2. High survivorship, maintenance of correction, and a low incidence of major complications was observed. The most common complication overall was lateral gutter impingement, which accounted for the majority of the non-revisional reoperations.

Comparison of the Outcome of the 3-Component Salto Total Ankle Arthroplasty for Ankle with Preoperative Varus, Valgus and Neutral Alignment in End-Stage Osteoarthritis

Category:Ankle; Ankle ArthritisIntroduction/Purpose:As the popularity of total ankle arthroplasty (TAA) increases, indication of TAA also expands. Recently, the ankles more than 20° of varus or valgus deformity in the coronal plane are treated with TAA. However, severe varus or valgus deformity should be corrected in the coronal plane to avoid residual mal-alignment that leads to instability, insert wear, and clinical failure. In this study, we compare the clinical and radiologic outcome of the Salto mobile bearing 3-component total ankle prosthesis for ankles with preoperative varus, neutral, and valgus alignment.Methods:TAA was performed in 101 consecutive ankles (99 patients) by a single surgeon using 3-component Salto total ankle implant from June 2014 to October 2019. A prospectively collected database was used to identify all patients who underwent primary TAA with a minimum 1-year follow-up. We classified the enrolled ankles as neutral, varus, or valgus groups. More than 10° of tibial anterior surface angle, talta tilt angle, tibial axis-talar dome angle, talar dome-ground surface angle (TD-GSA), or tibio- calcaneal angle was defined as varus or valgus groups. All patients were followed up at postoperative three months, six months, at one year and yearly thereafter. Clinical outcome scoring was done pre-operatively and post-operatively. American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot functional score, pain VAS, satisfaction score and clinical range of motion (ROM) were collected along with weight-bearing radiographs of the ankle. Post-operative coronal alignment of the component were evaluated with radiographs.Results:The average follow-up was 21.6 months (range, 12-71). Preoperatively, there were 63 ankles (62%) with varus deformity, 27 ankles (27%) with neutral alignment, and 11 ankles with valgus deformity. In preoperative varus group, 13 ankles (21%) were performed with concomitant lateral sliding calcaneal osteotomy, and 23 ankles (37%) with deltoid release. No additional procedures for the correction of ankle and hindfoot deformity were performed in preoperative neutral and valgus groups. VAS pain score and AOFAS score were significantly improved in all groups (p < 0.05). Overall satisfaction rate was 88%. After TAA, there were no significant radiologic alignment among the groups (3.9° (range, 0.7°~9.7°) in varus group, 4.1° (range, 0.4°~6.8°) in neutral group, and 2.2° (range, -0.4°~4.4°) in valgus group; p > 0.05).Conclusion:There was no significant difference in outcome among the varus, neutral, and valgus groups postoperatively in the TAA series using single Salto 3-componenet implant. Postoperative neutral alignment was achieved in all ankles. For favorable long-term outcomes, coronal alignment should be corrected with proper additional procedures in TAA.

Midterm Survivorship of the INBONE II Total Ankle Arthroplasty

The use of total ankle arthroplasty (TAA) in the treatment of ankle arthritis has grown substantially as advancements are made in design and surgical technique. Among the criteria guiding the choice between arthroplasty and arthrodesis, the long-term survival and postoperative outcomes are of crucial importance. Although outcomes of the INBONE I have been published, there is limited midterm survival data for the INBONE II. The purpose of this study was to determine the radiographic and patient-reported outcomes, and survivorship of this prosthesis in patients with a minimum 5-year follow-up. We retrospectively identified 51 ankles (46 patients) from 2010 to 2015 who underwent TAA with the INBONE II prosthesis at our institution. Of these, 44 cases had minimum clinical follow-up of 5 years (mean, 6.4; range 5-9). Median age was 66 years (range 42-81) and median BMI was 27.5 (range 20.1-33.0). A chart review was performed to record the incidence of revision and reoperation. Preoperative and postoperative radiographs were analyzed to assess the coronal tibiotalar alignment (TTA), the talar inclination angle, and the presence of periprosthetic lucencies and cyst formation. Preoperative and minimum 5-year postoperative Foot and Ankle Outcome Score (FAOS) subscales were compared. Survivorship was determined by incidence of revision, defined as removal of a metallic component. The survivorship at 5 years was 98% and the rate of reoperation was 7.8% (n = 4); 2 patients underwent irrigation and debridement for infection, 1 patient underwent a medializing calcaneal osteotomy, and 1 patient underwent open gutter debridement, 1 patient underwent a revision of a subsided talar component at 3.2 years after index surgery. Average postoperative TTA was 88.6 degrees, with 42 rated as neutral (85-95 degrees), 2 varus (<85 degrees), and no valgus (>95 degrees) ankles. At final follow-up, asymptomatic periprosthetic cysts were observed in 8 patients. All FAOS domain scores improved between preoperative and final follow-up. At midterm follow-up, we observed significant improvement in radiographic alignment and patient-reported outcome scores for the INBONE II total ankle prosthesis. In addition, this cohort has had a relatively low reoperation rate and high survivorship. Level IV, case series.

Early outcomes with the vantage total ankle prosthesis

The Vantage total ankle replacement is a modern prosthetic design not well investigated in the literature. The aim of the present study was to analyze the early outcomes and complications of the Vantage total ankle system. Twenty-two Vantage total ankle implants were included in this retrospective study. Survivorship, complication rate, patient satisfaction, postoperative brace use, and pain levels were evaluated. At a mean follow up of 24.6 months (range 24 to 32 months). there was a 4.54% (1/22) overall complication rate and 100% implant survivorship. Patient-reported pain scores decreased from an average 7.4 (range 5-10).preoperatively to 0.66 (range 0-3). postoperatively. Only 9.09% (2/22) of patients required a brace postoperatively, and there was a 100% patient-reported satisfaction rate. The Vantage total ankle system was associated with a low complication rate and positive early outcomes in terms of pain improvement and patient-reported satisfaction.

Emerging National Trends in Ankle Prosthesis: A 15-Year Analysis of the Italian National Hospital Discharge Records

Total ankle replacement (TAR) has gained popularity in recent years becoming the mainstream treatment for conditions like rheumatoid arthritis, posttraumatic arthritis and severe osteochondral lesions of the talus. The aim of the study was to assess the nationwide number of implants performed in a 15-year period (2001-2016) and to identify trends like patients’ interregional migratory flows and their accessibility to this procedure. Data for this study were obtained from the Italian National Hospital Discharge records (SDO), obtained from the National Ministry of Health. The selected SDOs were evaluated for demographic data, like the patient's age and gender, for geographical data, including the region of hospitalization and the region of origin of the patient, and for hospitalization data, like the hospital stay length and the principal source of payment. In a 15-year span, a sharp increase in the number of TARs was observed with a 600% growth. The incidence was 0.16 per 100,000 persons in 2001 and increased to 0.915 per 100,000 persons in 2016. Most TAR were performed in northern Italy (73.9%), followed by central Italy (16.7%) and lastly southern Italy (9.4%). The rates of utilization of TAR increased every year from 2001 to 2016, indicating that demand for ankle arthroplasties is growing faster regarding to other procedures performed in Italy. The surgical cost was covered, in the majority of cases, by the National Health System and may play a role in the rising rates of TAR.

Design and Numerical Characterization of a Human Ankle Prosthesis

This paper addresses to a finite element analysis in dynamic conditions of a human ankle joint prosthesis based on a cam mechanism design. The proposed ankle joint prosthesis mechanism is a parameterized one and was designed in order to fulfil main human locomotion tasks namely walking during daily activities. A proper 3D CAD model has been developed and the proposed cam mechanism ankle prosthesis was modelled and simulated into MSC Visual Nastran environment. Results of simulations demonstrate the engineering feasibility of the design and validate the proposed parameterized prototype.

Corin ankle arthroplasty: Case-series

BackgroundTotal Ankle Arthroplasty (TAA) is complex and can bring a wide variety of complications. Implant revision rates can vary from 4% to 8% in 5 years. Recent publications have shown good results in the short and intermediate follow-up and high patient satisfaction. The pre- and postoperative evaluation of these patients should include physical examination and objective radiographic measurements, which may have predictive value for implant failures and survivorship. In this paper we will present the results obtained with 29 patients treated with the Zennith (Corin Group, UK) total ankle prosthesis in Brazil. MethodsThis paper presents the results obtained with 29 patients treated with the Corin-Zennith prosthesis in three tertiary hospitals in Brazil, with an average follow-up of 5 years. The patients were submitted to clinical and radiographic evaluation. There were seventeen women and twelve men, ranging in age from 35 to 76 years, who were submitted to surgical treatment between January 16, 2013 and May 5, 2017. ResultsSeven patients (24%) presented cysts, being 4 (13.7%) tibial cysts and 3 (10.3%) tibial and talar cysts. Six patients (20.6%) presented talar subsidence and 3 (10.3%) presented tibial subsidence. Three patients (10.3%) presented component wear. VAS reduced and AOFAS and ROM increased in the post-operative period. The development of Cysts was associated with the theta angle and the difference in LTS (between the post and preoperative period) was associated with tibial subsidence. The complications rate was 44.8%, the revision rate was 6.9% and the survivorship rate was 93.1%. ConclusionThe Corin-Zennith prosthesis demonstrated to be a safe implant for improving functional parameters. Functional outcomes were not influenced for most commonly measured radiographic parameters. Further studies are needed to better understand these associations.

Effect of artificial surface shapes and their malpositioning on the mechanics of the replaced ankle joint for possible better prosthesis designs

BackgroundThe clinical outcomes of total ankle replacement are limited by prosthesis component malpositioning during surgery. The goal of this study is to assess the mechanical impact of this malpositioning in a validated computer model. MethodsIn a previously developed multi-body dynamic model of the human ankle complex three different artificial implants were designed, each one presenting a different approximation of the natural articular surfaces of the corresponding specimen. The most common implant translational and rotational malpositionings were defined and mimicked. Dynamic simulations of joint motion were run for the various surfaces and malpositionings. The same input loading conditions derived from a previous in-vitro experiment on the corresponding natural specimen were applied. FindingsFrom load-displacement graphs it was observed that all three artificial surfaces reproduced well physiological motion between the calcaneus and the tibia/fibula, with a maximum difference of 2°. It was found that antero-posterior translation of either the tibial or the talar component and inclination of the tibial component in the sagittal plane led to considerable increases in the range of motion. Antero-posterior and dorsiflexion of the tibial component resulted in an increased internal-external rotation by up to 3.5° and 4.0°, respectively. The corresponding increase of inversion-eversion was 5.0° and 6.5°. InterpretationThis study showed that relatively small surgical errors have great consequences in replaced joint mechanics. The present model can be used in future studies to analyse the effect of malpositioning with any specific current total ankle prosthesis.

Altering the tuning parameter settings of a commercial powered prosthetic foot to increase power during push-off may not reduce collisional work in the intact limb during gait.

Increased knee osteoarthritis risk in patients with unilateral lower extremity limb loss is attributed to increased intact limb loading. Modulating powered ankle prosthesis push-off power may be an effective way to modulate intact limb loading. We examined how changes in the parameter settings of a commercial prosthetic ankle affect power delivery during push-off and the resulting collisional work experienced by the intact limb in persons with unilateral lower extremity limb loss. Five subjects with unilateral transtibial amputation were fitted with a commercially available powered ankle prosthesis (Ottobock Empower). Subjects walked on a treadmill in seven conditions, where ankle power delivery settings were adjusted using methods accessible to clinicians. Kinetics and kinematics data were collected. Standard adjustment of parameter settings within the prosthetic foot did not alter timing of peak prosthesis power or intact limb collisional work but did have a significant effect on the magnitude of positive prosthesis ankle work. Increased prosthesis work did not decrease intact limb collisional work as predicted. Altering the parameter settings on a commercial powered ankle prosthesis affected the magnitude, but not the timing, of power delivered. Increased prosthesis push-off power did not decrease intact limb loading.

Ankle prosthesis design for transtibial amputation

People who suffer an amputation at the transtibial level choose to wear an ankle prosthesis to make their walk like a person without disabilities. In the present investigation, an ankle prosthesis design and simulation are made, which involves a restricted patella mechanism and a linear actuator capable of granting two degrees of freedom. A ball joint is designed where twelve springs that support the weight of a person are located, six springs comply with the eversion movement and the rest comply with the inversion movement, likewise, the actuator performs the dorsiflexion and plantar-flexion movements. The simulations were made in Inventor software. The results obtained on the ‘Y’ axis indicate a patella displacement in the inversion and eversion movement of 13.65 mm and 11.89 mm, respectively. These values are obtained when a tension of 1876.1 N is applied to the twelve springs. With these data obtained, stability and support for a person weighing 70 kg can be guaranteed, in addition, the established movement angles are com-plied. The prosthesis was built using additive and subtractive manufacturing.

Redesign of a Biomechanical Energy Regeneration-based Robotic Ankle Prosthesis using Indonesian Gait Data

In this research, the robotic ankle design from Arizona State University (ASU) known as SPARKy was redesigned to accommodate the specific needs of Indonesian people. Most active prosthetic legs are designed based on gait parameters for people from Western countries, which may differ for people from other cultures that have a different anthropometry and economic background. Indonesians have smaller actuating power characteristics compared to people from Western cultures due to their smaller average weight and body height. Thus, the applied design strategy took advantage of a biomechanical energy regeneration scheme to reduce the actuator input power requirement and the relatively smaller mechanical power of the typical Indonesian ankle to create a potentially affordable robotic ankle with a smaller actuator that meets the technical specifications. The specifications of the powered prosthetic ankle were determined through the same methods used by SPARKy. Only one low-level control system, to actuate normal walking, was designed and tested on a fully assembled robotic ankle. The test results indicated a promising low-level control, where the robotic ankle can follow the predetermined trajectory required to actuate normal walking based on Indonesian gait data.

Design and Preliminary Results of a Reaction Force Series Elastic Actuator for Bionic Knee and Ankle Prostheses

We present an actuator designed for untethered, lower-extremity powered-prostheses that replicates biological kinetic and kinematic function of both human knees and ankles. An electric energy optimal hardware specification is defined by kinematically clamping walking gait data to the dynamic model of a series elastic actuator (SEA) and searching for motor, reduction ratio, and spring. The actuator is shown to achieve the required torque, angle, and velocity requirements for nominal walking conditions on level ground as well as varied terrain. The performance of the actuator is demonstrated on benchtop and as worn by a human subject with unilateral below knee amputation. The resulting design is a moment-coupled cantilever-beam reaction-force SEA (MC-RFSEA) that has a nominal torque rating of 85Nm, repeated peak torque of 175Nm, 105 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> range of motion, and a hardware mass of 1.6kg. Preliminary results from level-ground walking with the actuator tested in an ankle configuration show an electric cost of transport of 0.053J/kg when walking at 1.5m/s.

The effect of powered ankle prostheses on muscle activity during walking

Individuals with transtibial amputation (TTA) walk with greater muscle activity and metabolic costs than non-amputees. Powered prostheses aim to address these deficits by replicating the active function of the biological ankle. The purpose of this study was to determine if people with TTA alter muscle activity when walking with a powered prosthesis, and if this change relates to changes in metabolic costs. Ten individuals with TTA and 10 non-amputees walked on a treadmill while we measured metabolic cost and muscle activity from 16 lower limb muscles. Participants with TTA walked with their prescribed unpowered prosthesis and a commercial powered prosthesis (BiOM T2, Bedford, MA, USA), in random order. The integrated EMG across the gait cycle was greater with the powered prosthesis for the intact limb gluteus medius (p = 0.002) and residual limb vastus medialis (p = 0.013). There were several non-significant, moderate-to-strong correlations between changes in muscle activity and changes in metabolic cost between prostheses (p > 0.0504). Decreased muscle activity in the residual limb gluteus medius correlated with lower metabolic cost (r = 0.543). In contrast, lower metabolic cost was correlated with increased residual limb rectus femoris activity (r = -0.627) and increased co-contractions in the residual limb thigh muscles in terminal stance (r = -0.585) and late swing (r = -0.754). Overall, there were no consistent changes in muscle activity in response to the powered prosthesis. The correlations suggest that individuals who can effectively stabilize their residual limb during stance are more likely to benefit metabolically.

2자유도 저관성 능동 발목 의족 개발 및 비평탄면 보행을 위한 임피던스 제어

In this paper, a lightweight low-inertia 2-DOF ankle prosthesis is presented. This prosthesis is designed to reduce the heterogeneity of amputees and enable them to walk comfortably with low effort. The compact size and low height of this prosthesis means that it can be widely used by amputees with various physical conditions. The proposed ankle prosthesis has two active joints in the sagittal and the coronal planes, and these joints are actuated by a parallel linkage mechanism, which helps amputees to walk normally and maintain balance when stepping on obstacles or uneven ground. A unique spring mechanism helps with propulsion without increasing the distal mass. This paper describes the kinematics of the proposed prosthesis and joint-level impedance control and presents a balancing control algorithm based on the human gait cycle. The height and weight of the developed ankle prosthesis are 220 ㎜ and 2.25 ㎏, respectively, which are comparable to those of commercial 1-DOF prostheses. The experiments conducted using the proposed prosthesis on even and uneven terrains demonstrated that the proposed 2-DOF prosthesis appropriately adapts to various ground conditions and consistently assists users with balance and propulsion.

Clinico-pathological diagnosis of Facioscapulohumeral Dystrophy in a 22-year-old Male

Background: Facioscapulohumeral dystrophy (FSHD) is a rare hereditary disease with a prevalence of 2.03–6.8 per 100,000 individuals. FSHD is the third most common type of muscular dystrophy after the Duchene muscular dystrophy and myotonic dystrophy. To the best of our knowledge, the current case report is the first to report probable FSHD case mainly diagnosed using clinico-pathological evidence from sub-Saharan Africa (SSA).&#x0D; Case Report: A 22-year-old right-handed male college student presented with progressive proximal muscular weakness associated with wasting. The weakness started from the bilateral facial muscles and progressively involved proximal upper and lower limbs muscles associated with scapular winging, waddling gait, and bilateral foot drops. His bulbar, sensory, autonomic, and cognitive systems were spared. Muscles EMG showed myopathic patterns and normal serum CK. Muscle biopsy from affected muscles showed variation in fiber size with groups of angular fibers, preserved fibers, and hypertrophic fibers with marked fibrosis and adipose tissue replacement with no apparent inflammation and necrosis which is consistent with pathological features of muscular dystrophy. Considering the clinical semiology, physical findings, EMG findings, and pathological findings diagnosis of FSHD of scapuloperoneal variant was made. The patient was managed with analgesics, nutritional advice, and ankle prosthesis for foot drops. Currently, the patient is in a similar condition with modest improvement in his musculoskeletal pain complaints.&#x0D; Conclusion: This case highlights the fact that a careful clinical evaluation with thorough utilization of diagnostic investigations available at our disposal may support the diagnosis of FSHD in resource-limited areas where the necessary genetic tests were not available.&#x0D; Keywords: facioscapulohumeral muscular dystrophy, dystrophy, clinico-pathology, sub-Saharan Africa

Evaluation of Continuous Walking Speed Determination Algorithms and Embedded Sensors for a Powered Knee &amp; Ankle Prosthesis

Dynamically altering the parameters for assistance in a lower limb prosthesis is a challenge that depends directly on the ability to estimate gait parameters. Machine learning algorithms present an opportunity to develop methods for continuously determining walking speed in different conditions. Current state-of-the-art solutions involve using wearable sensors such as IMUs to estimate these parameters. These methods require an entire gait cycle to update the walking speed; this leads to delays when responding to changing speeds and ultimately renders these methods ineffective for adaptation into real-time prosthesis control. In this study, we developed subject dependent and independent machine learning models for rapidly determining walking speed and evaluated on data collected from 6 individuals with unilateral transfemoral amputation walking on our robotic knee/ankle prosthesis. We evaluated the performance of these models across a variety of static walking speeds and dynamic speed trials. Our findings suggest that using machine learning models offers excellent accuracy for both subject dependent and subject independent algorithms (DEP RMSE: 0.014 $\pm$ 0.001 m/s, IND RMSE: 0.070 $\pm$ 0.007 m/s, (p < 0.05), with the advantage of real-time continuous determination at 50 Hz, which allows for good performance when rapidly changing walking speed. We also determine the most effective sensors to use for improving model performance. Our study provides valuable information for determining walking speed more reliably across different users and is robust to dynamic changes experienced in gait.

Reconstruction of a missing or insufficient distal fibula in the setting of a total ankle replacement: The Milanese technique

BackgroundThe presence of an intact distal fibula is reported as a prerequisite when considering total ankle replacement and its lack is usually considered a contraindication. The purpose of the study was to describe the results of a surgical technique to reconstruct the distal fibula (Milanese fibular reconstruction technique) in the setting of a total ankle replacement and insufficient fibula. MethodsRetrospective analysis of 15 patients (15 ankles) who underwent rotational fibular reconstruction technique with minimum follow-up of 24 months. Patients were evaluated preoperatively and at the last follow-up with AOFAS Ankle and Hindfoot score, VAS pain scale, SF-12 and range of motion. Standard weightbearing radiographs were used for radiographic assessment. ResultsThe average of all clinical scores significantly improved (P<.001). The average radiographic parameters showed a neutral alignment. No cases of reabsorption of the new lateral malleolus were observed even in cases with complications that accounted for 2 superficial wound infection and 2 deep infections. ConclusionsThe Milanese fibular reconstruction technique can successfully reestablish a lateral strut and in the setting of an ankle prosthesis in patients with an insufficient fibula.

Intermediate-Term Outcomes of a Third-Generation, 2-Component Total Ankle Prosthesis.

Short-term outcomes for the INBONE I and INBONE II tibial stems have been favorable. The INBONE-II talus has been shown to have lower reoperation and failure rates compared to its predecessor at short term follow-up. The purpose of the present study was to assess mid-term outcomes for the third generation, two component total ankle prosthesis at 5 to 9 years follow-up, evaluating both the tibial and talar components. All patients who underwent primary total ankle arthroplasty (TAA) with INBONE-II between July 2010 and July 2014 at a single institution and who were at least 5 years postoperative were included. A total of 15 ankles with a mean follow-up of 85 months (range, 61-113 months) met the criteria. Radiographs were assessed using coronal and sagittal alignment parameters preoperatively, at 6 weeks postoperatively, and at the most recent follow-up. Medical records were reviewed and revisions, reoperations, and complications were classified according to the criteria established by Vander Griend et al and Glazebrook et al, respectively. The survivorship of the prosthesis at a mean of 85 months was 93.7%. The coronal and sagittal tibiotalar alignments 6 weeks after surgery were 2.1 degrees (P = .081) and 36% (P = .15), respectively. Maintenance of this alignment was observed during the latest follow-up (P = .684 and P = .837, respectively). One ankle (6.7%) required early component revision, while 4 (26.7%) required a non-implant-related revision. Six complications (2 high grade, 1 intermediate, and 3 low) in 5 ankles (33.3%) were recorded according to the Glazebrook classification system. The present study is the first to report midterm follow-up after TAA with this third-generation, 2-component prothesis. High survivorship, maintenance of correction, and a low incidence of major complications were observed in this small case series. The most common complication overall was lateral gutter impingement, which accounted for the majority of the nonrevisional reoperations. Level IV, case series.

Stand-Up, Squat, Lunge, and Walk With a Robotic Knee and Ankle Prosthesis Under Shared Neural Control.

Emerging robotic knee and ankle prostheses present an opportunity to restore the biomechanical function of missing biological legs, which is not possible with conventional passive prostheses. However, challenges in coordinating the robotic prosthesis movements with the user's neuromuscular system and transitioning between activities limit the real-world viability of these devices. Here we show that a shared neural control approach combining neural signals from the user's residual limb with robot control improves functional mobility in individuals with above-knee amputation. The proposed shared neural controller enables subjects to stand up and sit down under a variety of conditions, squat, lunge, walk, and seamlessly transition between activities without explicit classification of the intended movement. No other available technology can enable individuals with above-knee amputations to achieve this level of mobility. Further, we show that compared to using a conventional passive prosthesis, the proposed shared neural controller significantly reduced muscle effort in both the intact limb (21–51% decrease) and the residual limb (38–48% decrease). We also found that the body weight lifted by the prosthesis side increased significantly while standing up with the robotic leg prosthesis (49%–68% increase), leading to better loading symmetry (43–46% of body weight on the prosthesis side). By decreasing muscle effort and improving symmetry, the proposed shared neural controller has the potential to improve amputee mobility and decrease the risk of falls compared to using conventional passive prostheses.