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PubMed2003

A fuzzy clustering neural network architecture for multifunction upper-limb prosthesis.

Accurate and computationally efficient means of classifying surface myoelectric signals has been the subject of considerable research effort in recent years. The aim of this paper is to classify myoelectric signals using new fuzzy clustering neural network (NN) architectures to control multifunction prostheses. This paper presents a comparative study of the classification accuracy of myoelectric signals using multilayered perceptron NN using back-propagation, conic section function NN, and new fuzzy clustering NNs (FCNNs). The myoelectric signals considered are used in classifying six upper-limb movements: elbow flexion, elbow extension, wrist pronation and wrist supination, grasp, and resting. The results suggest that FCNN can generalize better than other NN algorithms and help the user learn better and faster. This method has the potential of being very efficient in real-time applications.

Algorithms↗
PubMed1998

Fast and accurate automated measurements in digitized stereophotogrammetric radiographs.

Until recently, Roentgen Stereophotogrammetric Analysis (RSA) required the manual definition of all markers using a high-resolution measurement table. To automate this tedious and time-consuming process and to eliminate observer variabilities, an analytical software package has been developed and validated for the detection, identification, and matching of markers in RSA radiographs. The digital analysis procedure consisted of the following steps: (1) the detection of markers using a variant of the Hough circle-finder technique; (2) the identification and labeling of the detected markers; (3) the reconstruction of the three-dimensional position of the bone markers and the prosthetic markers; and (4) the computation of micromotion. To assess the influence of film digitization, the measurements obtained from nine phantom radiographs using two different film scanners were compared with the results obtained by manual processing. All markers in the phantom radiographs were automatically detected and correctly labeled. The best results were obtained with a Vidar VXR-12 CCD scanner, for which the measurement errors were comparable to the errors associated with the manual approach. To assess the in vivo reproducibility, 30 patient radiographs were analyzed twice with the manual as well as with the automated procedure. Approximately, 85% of all calibration markers and bone markers were automatically detected and correctly matched. The calibration errors and the rigid-body errors show that the accuracy of the automated procedure is comparable to the accuracy of the manual procedure. The rigid-body errors had comparable mean values for both techniques: 0.05 mm for the tibia and 0.06 mm for the prosthesis. The reproducibility of the automated procedure showed to be slightly better than that of the manual procedure. The maximum errors in the computed translation and rotation of the tibial component were 0.11 mm and 0.24, compared to 0.13 mm and 0.27 for the manual RSA procedure. The total processing time is less than 10 min per radiograph, including interactive corrections, compared to approximately 1 h for the manual approach. In conclusion, a new and widely applicable, computer-assisted technique has become available to detect, identify, and match markers in RSA radiographs and to assess the micromotion of endoprostheses. This new technique will be used in our clinic for our hip, knee, and elbow studies.

Automation↗
PubMed1990

Operator performance in myoelectric control of a multifunction prosthesis stimulator.

In this paper, a microcomputer-based system is described which facilitates the evaluation of different myoelectric control strategies. The system is based on an IBM-PC/AT microcomputer which generates and develops tracking targets, processes and displays the operator's response, and computes tracking performance. The dynamics of the prosthetic elbow, hand, and forearm are simulated in software which drives a stick figure in response to the operator's input. Performance is measured in terms of integral absolute error in target-response match. Control strategies to simulate different systems are easily modified through software and are evaluated under identical conditions. As a test of this evaluation system and to obtain some comparative data on control strategies, four strategies which are either in use or proposed for use are evaluated. The test procedure is divided into a control training session and a control evaluation session. Data collected from groups of three normally-limbed subjects per strategy over a period of five control evaluation sessions are presented. The results of this evaluation are discussed and improvements in the evaluation system suggested.

Data Collection↗
PubMed2004

Distal humerus fractures in elderly patients: results after open reduction and internal fixation.

PROBLEM: Fractures of the distal humerus are difficult to treat. In elderly patients, diminished bone mineral quality and increased trauma-associated joint destruction may make stable joint reconstruction even more problematic. Furthermore, comorbidities and poor tolerance of joint immobilization might be additional factors which influence elbow function negatively. Until now, disagreement has existed on how to treat these fractures in elderly patients. Recommendations range from conservative treatment to primary total elbow replacement. So far, reports in the literature on whether or not open reduction and internal fixation in these patients is justified are very rare. AIM OF THE STUDY: To analyze fracture patterns, surgical approach, complications, and functional results after open reduction and internal fixation in patients of age 60 years and older. PATIENTS AND METHODS: Retrospective clinical study of two university level 1 trauma centers, including 45 patients (median age 73 years; range, 61-92 years) with surgically treated distal humerus fractures. Fracture patterns were recorded according to their AO classification. All patients were treated by open reduction and internal fixation. A clinical and radiological follow-up was obtained after a minimum of 24 months following surgery (median 87 months; range, 24-121 months). Functional results were evaluated according to the Mayo Elbow Score. RESULTS: Fractures with complete joint involvement were seen most often. Taking the fracture type into consideration, functional results deteriorated with degree of joint involvement. Postoperative complication rate was high, predominantly seen as screw loosening and/or implant failure at the lateral column. Neverthless, functional results were preponderating good or excellent. Factors negatively influencing outcome were joint immobilization longer than 14 days and severe joint involvement. DISCUSSION: In elderly patients, distal humerus fractures, which are often considered "osteoporotic fractures," still remain one of the most demanding challenges in trauma surgery. The present study demonstrates that despite diminished bone quality and a high complication rate, open reduction and internal fixation in elderly patients is justified. CONCLUSION: Open reduction and internal fixation of distal humerus fractures in elderly patients should be the main goal, since good elbow function can be achieved in the majority of patients. Elbow immobilization longer than 14 days should be avoided. Stable implant anchorage at the lateral column remains problematic, reflecting a general potential for further implant improvements.

Aged↗
PubMed1982

Multifunctional prosthesis and orthosis control via microcomputer identification of temporal pattern differences in single-site myoelectric signals.

The paper discusses results of on-line tests on amputees and hemiplegics of multifunctional prostheses and orthoses control by identifying the parameters of single-site temporal EMG signal signatures. The results relate to tests on above-elbow amputees, on shoulder-disarticulation amputees (including a congenital disarticulation amputee) and on hemiplegics, varying from 5 to 50 years of age. The system employed is based on an 8-bit Intel 8080 microprocessor, when computation is in double precision, to obtain an effective 16-bit work-length. The system employs a sequential least-squares algorithm to identify a 4-parameter auto-regressive time-series model of the EMG signal, and a Bayesian rule discrimination algorithm.

Adolescent↗
PubMedDate not supplied

[Clavicula pro humero--a new surgical method for malignant tumors of the proximal humerus].

In the majority of cases with malignant tumors in the proximal part of the humerus a limb saving tumor resection is possible. Reconstruction of the defect is necessary to maintain the length of the arm and to create a fulcrum for elbow flexion and extension. Several methods of reconstruction have been described in the literature including the fixation of distal humerus to the second rib or to the clavicle by means of Küntscher-nails, the implantation of a proximal humerus prosthesis without or with accompanying bone transplantation, a bridging of the defect using an allograft or an arthrodesis of the shoulder joint using free or vascularized bone transplants. The following paper describes a new surgical procedure whereby the vascularization of the clavicle is preserved and the clavicle used to bridge the defect. Although the follow-up period of the patients operated on so far in this way is relatively short, the functional advantages of this operation over the other forms of reconstruction can already be observed.

Adult↗
PubMed2005

Functional restoration of elbow extension after spinal-cord injury using a neural network-based synergistic FES controller.

Individuals with a C5/C6 spinal-cord injury (SCI) have paralyzed elbow extensors, yet retain weak to strong voluntary control of elbow flexion and some shoulder movements. They lack elbow extension, which is critical during activities of daily living. This research focuses on the functional evaluation of a developed synergistic controller employing remaining voluntary elbow flexor and shoulder electromyography (EMG) to control elbow extension with functional electrical stimulation (FES). Remaining voluntarily controlled upper extremity muscles were used to train an artificial neural network (ANN) to control stimulation of the paralyzed triceps. Surface EMG was collected from SCI subjects while they produced isometric endpoint force vectors of varying magnitude and direction using triceps stimulation levels predicted by a biomechanical model. ANNs were trained with the collected EMG and stimulation levels. We hypothesized that once trained and implemented in real-time, the synergistic controller would provide several functional benefits. We anticipated the synergistic controller would provide a larger range of endpoint force vectors, the ability to grade and maintain forces, the ability to complete a functional overhead reach task, and use less overall stimulation than a constant stimulation scheme.

Algorithms↗
PubMed1984

Management of the infected total joint arthroplasty.

Infection is the most severe complication of total joint arthroplasty. Prompt recognition and correct management, as well as prophylaxis against infection, are essential to minimize morbidity and maximize function. In this article, the etiology and diagnosis of prosthetic infection and the management of infected total arthroplasties of the hip, knee, ankle, shoulder, elbow, and wrist are discussed.

Anti-Bacterial Agents↗
PubMed1989

Survivorship of unconstrained total shoulder arthroplasty.

The results of fifty-three unconstrained (Neer-II or Gristina) total shoulder arthroplasties were reviewed with the use of survivorship analysis. Failure was defined as the need for revision or the onset of the patient's dissatisfaction. The method of survivorship analysis is presented in detail. Fifty-one total shoulder arthroplasties were followed for a minimum of two years (average, sixty-seven months). The results are reported with the use of the American Shoulder and Elbow Surgeons' rating form. After eleven years, the survivorship was 73 per cent for all prostheses, 71 per cent for the Neer prostheses, and 92 per cent for all prostheses in patients who had rheumatoid arthritis. Data on survivorship of the Gristina prosthesis were available after four years only, at which time it was 100 per cent. The relief of pain, which was the primary reason for the operation, was good or excellent in 82 per cent, improved in 6 per cent, and poor in 12 per cent of the shoulders in these patients.

Adult↗
PubMed1995

[Humeral retroversion and shoulder prosthesis].

PURPOSE OF THE STUDY: From a theoretical point of view, humeral torsion is described as the angle between the transcondylar plane and the posteromedially facing joint surface of the humeral head. In this study, humeral torsion was also identified as the angle between the anatomical neck of the humerus and at the inferior part the axis of rotation of the elbow and the axis of the forearm. MATERIALS: 60 cadaveric humeral shafts were obtained. The axis were defined and measured by CT Scans. METHODS: The orientation of the cartilage of the humeral head was determined as a line perpendicular to the limits of the joint area of the humeral head. The axis of the humeral anatomical neck was defined as the plane that contains both the long axis of the humerus and the center of the humeral head. The rotation axis of the elbow was defined as the line passing through the centers of the capitellum and the trochlear sulcus. RESULTS: The angle between the orientation of the humeral head and the orientation of the transcondylar line averaged 23 degrees. The angle between the humeral neck and the orientation of the transcondylar line averaged 38 degrees. The angle between the humeral neck and a line perpendicular to the axis of the forearm averaged 41 degrees. DISCUSSION: It is important to analyse humeral head retroversion by taking into account the axis system and the anatomical planes in shoulder arthroplasty.

Humans↗
PubMed1993

Lightweight prostheses for bilateral below-elbow amputees.

In view of the anticipated activity of the patient and working environment, lightweight prostheses were designed for an adult female, bilateral below-elbow (BE) amputee at NIRTAR to provide the greatest degree of function. The prostheses were fabricated using lightweight materials and new techniques. Depending on the stump length there were two different types of lightweight prostheses designed and successfully used, (1) an endoskeletal BE prosthesis and (2) an exoskeletal BE prosthesis. After periodic follow-up and evaluation the function of the prostheses was found to be most satisfactory. By reducing the weight considerably compared to other available alternatives, it is more likely that the amputee will make use of the prostheses to efficiently perform various activities. The new prosthesis designs may counteract the high rejection rate of old conventional ones and the principle may be applied to the fabrication of all BE prostheses.

Activities of Daily Living↗
PubMed2002

The influence of weight and starting height on lifting mechanics in lower extremity amputees.

This study compares the lifting mechanics of lower extremity amputees to controls and describes the influence of weight lifted and starting height on lifting style. Subjects included three individuals with transtibial amputation (TTA), two individuals with transfemoral amputation (TFA), and three able-bodied controls (CO). Amputee subjects performed six repetitions of six weights, randomly ordered, from two starting heights. TTA lifted from 30 cm and knee height, TFA from knee and thigh height, and controls from all three heights. Data were obtained from a work simulator, force plate, and a motion analysis system, with starting posture index, lateral sway index, lift duration, synchrony index, and hip moments and elbow moments as dependent measures. The results for each lifting height were analyzed using a mixed model repeated measures MANOVA to test for group and weight differences and post hoc tests were applied when appropriate. Results suggest that healthy lower extremity amputees who have had a number of years to adjust to their prosthesis and develop compensatory strategies can complete a repetitive lifting task at a performance level very similar to able-bodied controls. The most consistent group differences detected were in the timing parameters: synchrony and duration. TTA and TFA tended to lift with less synchronization of hip and knee movements than able-bodied controls and to initiate the lift with their upper bodies. In contrast, able-bodied controls tended to move their upper and lower bodies more synchronously during the lift. TTA had longer lift durations than CO. In terms of stability and moments generated, TTA lifted very similarly to controls. TFA used a different lifting style that involved higher moments and more use of the upper body, particularly for lifts of heavier weights. TFA appeared to be less stable than CO, while TTA did not appear to be less stable than CO.

Adaptation, Biological↗
PubMed1995

Elbow osteoarthritis and a massive forearm cyst. A case report.

Despite exhaustive evaluation, a massive forearm cyst in a 74-year-old man with elbow osteoarthritis could not be diagnosed. The patient had total elbow arthroplasty, and the cyst did not recur postoperatively. Osteoarthritis presumably caused the huge, but noncommunicating, synovial forearm cyst.

Aged↗
PubMed1977

[Paresis of the brachial plexus: subcapital varus osteotomy, arthrodesis of shoulder joint and above-elbow amputation (author's transl)].

In brachial plexus paresis with partial sensory sparing in the upper arm and complete motor paralysis we amputate through the humerus at the distal limit of sensation. The remaining proximal humerus is fixed by an arthrodesis of the shoulder joint, combined with a varus-osteotomy below the head. This increases with axillary space, facilitates the fitting of a prosthesis and improves care of the skin in this critical area. It also improves the outline of the shoulder the muscles of which shrink.

Amputation, Surgical↗
PubMedDate not supplied

Neer Award 2005: The Grammont reverse shoulder prosthesis: results in cuff tear arthritis, fracture sequelae, and revision arthroplasty.

This clinical study was performed to analyze the midterm results and potential complications of the reverse prosthesis in different diagnosis. Forty-five consecutive patients with Grammont prosthesis were evaluated clinically and radiographically with a mean follow-up of 40 months (range, 24-72 months). The indication was a massive and irreparable cuff tear associated with arthrosis (CTA) in 21 cases, fracture sequelae (FS) with arthritis in 5 cases, and failure of a revision arthroplasty (revision) in 19 cases. Fourteen complications occurred in 11 patients. 3 dislocations, 3 deep infections (all 3 in the revision group), 1 case of aseptic humeral loosening, 2 periprosthetic humeral fractures, 1 intraoperative glenoid fracture, 1 wound hematoma, 2 late acromial fractures, and 1 axillary nerve palsy. Of the patients, 10 (22%) required further surgery: 4 reoperations, 4 prosthesis revisions, and 2 prosthesis removals. Complications were higher in revision than in CTA (47% vs. 5%). All 3 groups showed a significant increase in active elevation (from 55 degrees preoperatively to 121 degrees postoperatively) and Constant score (from 17 to 58 points) but no significant change in active external rotation (from 7 degrees to 11 degrees ) or internal rotation (S1 preoperatively and postoperatively). Of the patients, 78% were satisfied or very satisfied with the result and 67% had no or slight pain. However, the postoperative Constant score, adjusted Constant score, and American Shoulder and Elbow Surgeons shoulder score were all significantly higher in the CTA group with as compared with the revision group (P = .01, .004, and .002, respectively). Scapular notching was seen in 24 cases (68%). No glenoid loosening was observed at current follow-up, even when the notch extended beyond the inferior screw (28% of cases). Atrophy of severe fatty infiltration of the teres minor was associated with lower external rotation (15 degrees vs 0 degrees , P = .02) and lower functional results (Constant score of 46 points vs 66 points, P < .007). The Grammont reverse prosthesis can improve function and restore active elevation in patients with incongruent cuff-deficient shoulders; active rotation is usually unchanged. Results are less predictable and complication and revision rates are higher in patients undergoing revision surgery as compared with those in patients with CTA. Results of the reverse prosthesis depend on the diagnosis and on the remaining cuff muscles, specifically the teres minor. Surgeons should be vigilant with regard to low-grade infection in revision surgery.

Aged↗
PubMed1990

Shoulder function after prosthetic replacement of proximal humerus.

Between 1973 and 1985 eighteen patients with bone tumours and two patients with comminuted fractures had their proximal humerus replaced with a custom made isoelastic hemiendoprosthesis. In 1987 a clinical and radiographical review was performed of eleven patients with a mean follow up time of seven years, range 3-10 years. Four patients had pain at rest and six patients experienced severe pain on exertion. Active range of motion was poor and constituted only half of the corresponding range of passive motion. Shoulder girdle muscles were generally weak, only one patient could keep the arm straight in a flexed or abducted position. All patients had returned to their previous occupations, but their ability to perform ADL functions was poor. Rotator cuff insufficiency was considered to be the major cause of poor shoulder function. In comparison to most other surgical alternatives in tumour cases endoprosthetic replacement of the proximal humerus appears to be a safe and reliable method. The endoprosthesis gives stability to the arm and normal elbow and hand function is preserved.

Adult↗