Prosthetic Forearm Research Articles

A Single-Center Experience with Forearm Arteriovenous Loop Grafts for Hemodialysis

Autogenous arteriovenous fistula (AVF) remains the standard of hemodialysis (HD) access; however, it cannot be reasonably obtained in all patients. For patients with contraindications to AVFs, prosthetic arteriovenous graft (AVG) remains an alternative. AVGs are plagued by high failure rates; however, there is a paucity of literature examining this. This study aims to examine a single-center review of outcomes of forearm loop AVGs in patients requiring HD access. A single institution, retrospective chart review was completed from 2012 to 2019, including demographics, end-stage renal disease etiology, brachial vessel diameters, and comorbidities. Logistic regression and Cox proportional hazard models were evaluated. Outcomes were defined as primary patency (time elapsed from graft creation until it was utilized as the patient's primary access), primary-assisted patency (time from primary access to intervention to maintain patency), and functional patency (time from graft placement until graft failure). Additionally, multinomial regression models were used to evaluate associations with categorical number of required interventions. Ninety-eight patients [mean age 61.8 (13.9) years, 42.9% female] were identified as having brachial artery to brachial vein AVG creation during the study period, of which 75% achieved primary patency. Primary-assisted patency was 0.36 [standard error (SE) 0.07] at 6months and 0.12 (SE 0.05) at 1year. Functional patency was 0.75 (SE 0.07) at 6months and 0.43 (SE 0.09) at 1year. No association between preoperative vessel diameters and primary-assisted or functional patency was observed. Interestingly, there was a significant negative association between previous ipsilateral access and achievement of primary patency with a 60% decrease in odds of achieving primary patency in patients with previous ipsilateral access [odds ratio 0.4, 95% confidence interval (CI) 0.1-0.9, P=0.03]. There was also noted to be a significant association between the presence of an ipsilateral catheter and increased risk of subsequent abandonment of the AVG (hazard ratio 2.6, 95% CI 1.1-5.8, P=0.02). Prosthetic forearm loop AVGs remain hindered in their utility as they show high rates of graft failure within a year of creation. A significant patient-specific factor leading to this was not clearly demonstrated. As guidelines change regarding the nature of dialysis access for patients on HD, these results draw into question the utility of prosthetic forearm loop grafts in patients requiring long-term HD access.

A Single Center Experience With Forearm Arteriovenous Loop Grafts For Hemodialysis

<h3>OBJECTIVES</h3> Autogenous arteriovenous fistula (AVF) remains the standard of care for hemodialysis (HD) access, however, it cannot be reasonably obtained in all patients. For patients with contraindications to AVFs, prosthetic arteriovenous graft (AVG) remains an alternative. AVGs are plagued by high failure rates, however, there is a paucity of literature examining this. This study aims to examine a single-center review of outcomes of forearm loop AVGs in patients requiring HD access. <h3>METHODS</h3> A single institution, retrospective chart review was completed from 2012-2019, including patient demographics, end-stage renal disease (ESRD) etiology, brachial artery and vein diameters, and comorbidities. Logistic regression and cox proportional hazard models were evaluated. Outcomes were defined as length of primary patency (time from graft placement to intervention to maintain patency) and secondary patency (time from graft placement until graft failure despite intervention). <h3>RESULTS</h3> 98 patients [mean age 61.8(13.9) years, 42.9% female] were identified as having brachial artery to brachial vein AVG creation during the study period. Primary patency was 0.36 (SE 0.07) at six months, 0.12 (0.05) at one year. Secondary patency was 0.75 (0.07) at six months and 0.43 (0.09) at one year (see figure 1 below). No association between preoperative vessel diameters and primary or secondary patency was observed. <h3>CONCLUSION</h3> Prosthetic forearm loop AVGs remain hindered in their utility as they show high rates of graft failure within a year of creation. A significant patient-specific factor leading to this was not clearly demonstrated. As guidelines change regarding the nature of dialysis access for patients on HD, these results draw into question the utility of prosthetic forearm loop grafts in patients requiring long-term HD access.

Development of Multi-DoFs Prosthetic Forearm based on EMG Pattern Recognition and Classification

This paper presents a multiple DoFs (degrees-of-freedom) prosthetic forearm and sEMG (surface electromyogram) pattern recognition and motion intent classification of forearm amputee. The developed prosthetic forearm has 9 DoFs hand and single-DoF wrist, and the socket is designed considering wearability. In addition, the pattern recognition based on sEMG is proposed for prosthetic control. Several experiments were conducted to substantiate the performance of the prosthetic forearm. First, the developed prosthetic forearm could perform various motions required for activity of daily living of forearm amputee. It was able to control according to shape and size of the object. Additionally, the amputee was able to perform ‘tying up shoe’ using the prosthetic forearm. Secondly, pattern recognition and classification experiments using the sEMG signals were performed to find out whether it could classify the motions according to the user’s intents. For this purpose, sEMG signals were applied to the multilayer perceptron (MLP) for training and testing. As a result, overall classification accuracy arrived at 99.6% for all participants, and all the postures showed more than 97% accuracy.

Design and Integration of an Inexpensive Wearable Mechanotactile Feedback System for Myoelectric Prostheses.

The aim of this paper was to demonstrate the functionality of an inexpensive mechanotactile sensory feedback system for transhumeral myoelectric prostheses. We summarize the development of a tactile-integrated prosthesis, including 1) evaluation of sensors that were retrofit onto existing commercial terminal devices; 2) design of two custom mechanotactile tactors that were integrated into a socket without compromising suction suspension; 3) design of a modular controller which translated sensor input to tactor output, was wirelessly adjusted, and fit within a prosthetic forearm; and 4) evaluation of the system with a single transhumeral participant. Prosthesis functionality was demonstrated over three test sessions; the participant was able to identify tactor stimulation location and demonstrated a reduction in grasp force with the mechanotactile stimulation. This system offers an inexpensive and modular solution for integration of a mechanotactile sensory feedback system into a prosthetic socket without compromising the suction seal. These principles can be applied in future studies to investigate the direct impact of sensory feedback on tangible outcomes for prosthetic users, thereby reducing barriers to clinical translation.

Pre-clinical evaluation of a natural prosthetic elbow control strategy using residual limb motion and a model of healthy inter-joint coordinations

A gap has been growing between the mechanical features of newly commercialized prosthetic devices and the control strategies available to the users. The prosthetic joints are controlled sequentially via myoelectric control, and each actuation requires the user's attention. Because of a complex control scheme, transhumeral amputees are generally equipped with a 1-degree-of-freedom myoelectric hand, a myoelectric wrist rotator, and a manually locked elbow. The prosthetic forearm position, adjusted before the movement, is not involved in the overall upper limb movements, resulting in the development of compensatory strategies. A promising solution to improve prosthetic control utilizes the residual limb motions to control the elbow. Previous studies have shown that elbow motion could be predicted from measures of the residual limb movements and an inter-joint coordination model. This study is the first to report the utilization of an automatically driven prosthetic elbow by a transhumeral amputee. The participant pointed at targets with a prosthesis prototype including a modified motorized elbow. The prosthetic elbow motion was derived from a generic model of inter-joint coordinations, and IMU-based residual limb measurements. The participant performed also the task with the prosthetic elbow implemented with his own myoelectric control strategy. Body movements were assessed with the data recorded with a motion capture system. The patient achieved the pointing task with a better precision when the elbow was myoelectrically-driven. However, these movements required important trunk compensations. Trunk movements were smaller with residual limb motion-based elbow control, which enabled a more natural overall body behavior with synchronous shoulder and elbow motions. Due to socket impairment, but also to post-amputation body scheme modifications and discrepancies between healthy and artificial limbs, the participant's residual limb amplitudes were different of the ones of healthy shoulder movements for the same tasks. This work questions the paradigm whereby a prosthetic elbow can be intuitively and naturally used by an amputee while its motion is derived from healthy individual data. Although there is a need for novel modeling approaches to build an inter-joint coordination model adapted to each user, residual limb motion-driven prosthetic elbow enables simultaneous control of elbow and end-effector, and restores a more natural body behavior.

Introduction of arteriovenous grafts with graft insertion anastomosis for hemodialysis access

ObjectiveAn arteriovenous bridging graft is a viable option for patients with compromised arteries or veins because of advanced age or diabetes. Arteriovenous graft with graft insertion anastomosis (AVGI) is the novel technique for graft-vein anastomosis where the prosthesis is inserted into the vein, and the anastomosis is performed on the surface of the prosthesis. This study assessed the short-term and long-term results of AVGI to clarify the efficacy of this technique. MethodsBetween 2010 and 2015, AVGI was performed in graft-vein anastomosis of prosthetic forearm loop access. Characteristics and level of complications were assessed. To evaluate the long-term results, functional graft patency and frequency of percutaneous transluminal angioplasty were examined. ResultsThe study comprised 58 patients. There were no deaths related to the surgery. The time of hemostasis after AVGI was recorded at 0 seconds because no bleeding from the suture holes was seen. At 1, 2, and 3 years, primary patency were 45.1% ± 7.5%, 23.1% ± 7.5%, and 23.1% ± 7.5%, respectively, and assisted primary patency rates were 59.4% ± 7.2%, 50.8% ± 7.6%, and 50.8% ± 7.6%, respectively. Secondary patency rates at 4 and 5 years were 100% ± 0% and 94.1% ± 5.7%, respectively. The frequency of percutaneous balloon angioplasty to maintain the patency was 1.61 ± 0.53 times per year. Graft infection occurred in four patients (6.9%). ConclusionsAVGI is an advantageous technique for graft vein anastomosis in an arteriovenous bridging graft in both the short-term and long-term.

Prospective Evaluation of Ischemia in Brachial–Basilic and Forearm Prosthetic Arteriovenous Fistulas for Hemodialysis

Ischemia is a devastating complication after arteriovenous fistula (AVF) creation. When not timely corrected, it may lead to amputation. Symptomatic ischemia occurs in 3.7-5% of the hemodialysis population. Upper arm AVFs have a higher incidence of ischemia compared to forearm AVFs. As more patients may need upper arm AVFs in the growing and older hemodialysis population, occurrence of symptomatic ischemia may increase. The purpose of this study is to identify predictors for occurrence of ischemia. A prospective evaluation of ischemia was performed in patients randomised for either a brachial-basilic (BB-) AVF or a prosthetic forearm loop AVF. Clinical parameters, preoperative vessel diameters, access flows, digital blood pressures, digit-to-brachial indices (DBI) and interventions for ischemia were recorded. Sixty-one patients (BB-AVF 28) were studied. Seventeen patients (BB-AVF 8) developed ischemic symptoms. Six patients (BB-AVF 3) needed interventions for severe symptoms. Age, history of peripheral arterial reconstruction and radial artery volume flow were significant predictors for the occurrence of ischemia. Symptomatic ischemia occurred in 28% of patients with brachial-basilic and prosthetic forearm AVFs. Age, history of peripheral arterial reconstruction and radial artery volume flow might be important for prediction of ischemia.

Steal in Hemodialysis Patients Depends on Type of Vascular Access

To study incidence and severity of steal phenomena in hemodialysis patients and to investigate possible methods for its detection. A questionnaire was composed based on a literature search. A subgroup of patients having steal as identified by the questionnaire was studied using physical examination, arterial blood pressure, skin temperature, digital oxygenation, grip strength and plethysmography. Contralateral arms served as controls. A cold hand was present in 50% of the patients with a brachiocephalic (BC) arteriovenous fistula (AVF, n = 28) compared to 25% of prosthetic forearm loops (loop, n = 27) and 12% of the radiocephalic (RC, n = 65, p < 0.05) fistulas. Diabetics were at risk for steal (p < 0.001). Intensity of steal was not related to magnitude of access flow. Digital skin temperatures and grip strength were lower in steal hands (p < 0.02). Manual compression of the AVF normalised low digital pressures in steal hands (106 +/- 33 vs 154 +/- 25 mmHg, p < 0.001, contralateral side 155 +/- 21 mmHg). Mild to moderate steal symptoms are common in a hemodialysis patient. Individuals with a BC are at a higher risk for developing complaints associated with reduced hand circulation compared to patients with a RC or loop. Low finger pressures in the presence of steal symptoms are usually reversible.

Autogenous Radial-Cephalic or Prosthetic Brachial-Antecubital Forearm Loop AVF in Patients With Compromised Vessels? A Randomized, Multicenter Study of the Patency of Primary Hemodialysis Access

Autogenous Radial-Cephalic or Prosthetic Brachial-Antecubital Forearm Loop AVF in Patients With Compromised Vessels? A Randomized, Multicenter Study of the Patency of Primary Hemodialysis Access

Upper Arm Arteriovenous Fistula Versus Forearm Looped Arteriovenous Graft for Hemodialysis Access: A Comparative Analysis

If an autogenous wrist radiocephalic arteriovenous fistula cannot be created, the next choice for chronic hemodialysis access may be a prosthetic forearm looped arteriovenous graft (FAL-AVG) or a native upper arm arteriovenous fistula (UA-AVF). We reviewed our experience with these two forms of dialysis access to determine which is preferable. Patient medical records were retrospectively reviewed. The main outcomes were time to first use, complications, and reinterventions as well as primary and assisted primary patency. Eighty-six patients underwent creation of UA-AVF, and 60 patients underwent placement of FAL-AVG. Time to first use was 3.8 months for UA-AVFs vs. 1.8 months for FAL-AVGs (p < 0.018). Complication rates were 42% vs. 65% for UA-AVFs vs. FAL-AVGs, respectively (p = 0.006). Thrombosis was more common in FAL-AVGs than UA-AVFs (42% vs. 17%, p = 0.001), as was nonelective reintervention (50% vs. 30%, p = 0.016). Patency rates were similar at 1 and 2 years. Although UA-AVFs and FAL-AVGs share similar early patency rates, UA-AVFs may be a better choice for chronic hemodialysis access because of a lower incidence of complications and nonelective reinterventions. To maximize the benefits of UA-AVFs, however, early surgical referral is required.

Excellent performance of one-stage brachial–basilic arteriovenous fistula

According to the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) and the European Guidelines, the first and second choice for vascular access for haemodialysis are the radial-cephalic and brachial-cephalic arteriovenous fistula (AVF). Autogenous fistulas have a longer functional lifetime, less thrombotic complications and a lower infection risk compared with prosthetic implants. If it is impossible to create a brachial-cephalic AVF or after failure, either a brachial-basilic (BB) or a prosthetic forearm loop AVF may be considered. To determine the outcome of BB-AVFs, we retrospectively surveyed the results of this type of vascular access. All BB-AVF patient records over a 6 year period were subtracted from an academic hospital registry. Primary failure and primary, assisted primary and secondary patency rates were calculated with the Kaplan-Meier method. Sex, diabetes mellitus (DM), pre-operative duplex diameters, complications and interventions were recorded and correlated with the patency rates. A total of 31 BB-AVFs were created in a one-stage surgical procedure. Of the patients, 36% were male and 19% had DM. Only one patient had a primary failure, leaving 30 (97%) of the BB-AVFs functional for dialysis treatment. Four patients died within 1 year after the operation, one of them from a catheter sepsis. Primary, assisted primary and secondary patency rates after 1 year were, 58, 83 and 90%, respectively. Patient characteristics and pre-operative duplex parameters did not influence patency rates. The BB-AVF is an excellent third choice option for vascular access.

生EMG信号による電動義手の制御

生EMG信号による電動義手の制御

Bio-mimetic Control of An Externally Powered Prosthetic Forearm Based on EMG Signals.

Bio-mimetic Control of An Externally Powered Prosthetic Forearm Based on EMG Signals.

超音波モータを用いた3自由度前腕筋電義手

超音波モータを用いた3自由度前腕筋電義手