[Perspectives of artistic prosthesis design and prosthesis construction].
Explore the source record for details and available documents.
Artificial Limbs↗
SEARCH · PubMed Health
Results for “Prosthesis Design”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A new patella prosthesis. Design and application.
The new patella prosthesis design is based on an anatomical study of 80 arthritic patellas and on the normal patellofemoral contact area under loading in cadaver knees. The metal dome-shaped prosthesis is attached by a central pin. The patellar prosthesis is constructed either of metal or plastic for use in combination with the Hospital for Special Surgery design of total knee prosthesis. Methylmethacrylate is used to supplement the fixation after resection of the abnormal patellar articular surface. The fixation tests gave excellent laboratory results for contact area and stability. The prosthesis has been used in 19 cases with encouraging early results.
Adult↗
Biomechanical evaluation of metacarpophalangeal joint prosthesis designs.
A laboratory biomechanical analysis of metacarpophalangeal joint prosthesis designs was done with fresh cadaver finger rays. The center of rotation, range of motion, tendon excursion, and fingertip force were determined on the specimens before and after implanting Swanson, Niebauer, Steffee II, St. Georg-Buchholz, Schultz, and modified Strickland prostheses. Their biomechanical behavior varied considerably and none duplicated the normal metacarpophalangeal (MP) joint. Each has design characteristics that may be clinically advantageous as well as disadvantageous. Irrespective of the design, the studies done cannot be divorced from the following factors: (1) implant material properties--silicone rubber implants buckled with tendon loading; this deformity created a significant flexor mechanical advantage and an extensor mechanical disadvantage; (2) implant fixation--freely movable implant stems dampened part of the applied load; braided suture provided inadequate immediate fixation; (3) implantation technique--the articulated prostheses can be technically unforgiving; errors in technique resulted in alteration of their biomechanical behavior.
Biomechanical Phenomena↗
Prosthesis design for osseointegrated implants in the edentulous maxilla.
The position of osseointegrated implants in the edentulous maxilla is dictated by available bone and can vary widely among patients. Anatomy limits the amount of bone available for placement of osseointegrated implants. With increasing resorption, the number, length, and position of implants are further compromised. Bone grafts are frequently needed to place implants of adequate length. The variability of implant placement indicates the need for multiple prosthesis designs in the maxilla. Prosthesis design considerations are suggested for patients with minimal, moderate, and severe resorption of the edentulous maxilla.
Alveolar Bone Loss↗
A study of Chinese knee joint geometry for prosthesis design.
This study for the first time provides the geometric parameters of the knee joint of Chinese, which is indispensible to the design of knee prosthesis used for compatriotic patients. Thirty-five items, including linear, radial and angular measurements, were taken from 105 cadaveric knees and knee X-ray films of 1,100 subjects. The method and calculation for proper correction of the X-ray image magnification and joint cartilage space was established. Correlation was found to exist between the X-ray correction coefficients and the body weight, which formed the basis for individualized correction of X-ray measurements. Statistical analysis revealed that most of the linear and radial measurements were highly related while the angular measurements were independent of others. Principal component analysis showed that the width of femoral condyle might be taken as the leading index in determining the dimension of the knee, and regression functions were established to supply the serial parameters for prosthetic design. Multivariate discriminate functions could aid the selection of knee prosthesis.
Anthropometry↗
Obturator prosthesis design for acquired maxillary defects.
Fabrication of obturator prostheses does not require a special ability to fabricate a prosthesis extension into a defect or an arbitrary extension of a prosthesis into a defect. Fabrication of an obturator prosthesis depends on the application of basic prosthodontic principles that are used in the treatment of patients without maxillary defects. Some principles must be modified because of the defect and the character and position of the remaining structures. The defect, in conjunction with the remaining structures, must be used to provide support, retention, and stability of an obturator prosthesis. If basic prosthodontic principles are applied the size and extension of the obturator will be determined, and the extensive variation so commonly seen in obturators will be minimized. Acceptable prosthodontic care for the patient with the acquired maxillary defect should include cautious prosthesis design combined with routine maintenance care to provide comfort, function, cosmetics, and minimal change to the compromised remaining structures.
Alveolar Process↗
[A study on knee joint geometry in Chinese: significance to prosthesis design].
This study for the first time provided the geometric parameters of knee joints in Chinese, which are indispensable for the design of domestic knee prosthesis. Thirty five items, including linear, radial and angular measurements, were taken from 105 cadaver knees and knee X-ray films of 100 subjects. The method and calculation for proper correction of the X-ray image magnification and joint cartilage space was established. Correlation between the X-ray correction coefficients and the body weight was found to exist, and it formed the basis for individualized correction of X ray measurements. Statistical analysis revealed that most of the linear and radial measurements were highly related while the angular measurements were independent of others. Principal component analysis showed that the width of femoral condyle might be taken as the leading index in determining the dimension of the knee, and regression functions were established. Multivariate discriminate functions could aid the selection of knee prosthesis.
Adolescent↗
The derivation of elbow joint forces, and their relation to prosthesis design.
A literature review showed a lack of accurate data for upper limb joint forces. After discussing methods to determine muscle forces, the physiological cross-sections of muscles were used to estimate their strengths. Elbow joint forces were predicted for isometric actions which gave severe loading conditions. The predicted forces were discussed in relation to prosthesis design, and the use of a radial head replacement was recommended.
Biomechanical Phenomena↗
The mechanics of the knee and prosthesis design.
The mechanisms controlling and limiting movement and serving to transmit load between the femur and the tibia are discussed. Having accounted for the transmission of all components of force and couple across the joint and noted the load-bearing role of the menisci, some principles which might guide the design of knee prostheses are deduced. It is shown that current designs transgress some of these principles. An experimental prosthesis is then described, which incorporates analogues of the natural menisci. The possible practical application of this novel principle has been studied in cadaveric human joints and in living patients.
Biomechanical Phenomena↗
[Prosthesis design for a toothless maxilla in a case of an enlarged tuberosity].
Explore the source record for details and available documents.
Denture Design↗
Range of motion studies for total hip replacements. A comparative study with a new experimental apparatus.
Significant differences in ROM exist between different THR prosthesis designs: several of the prosthesis designs tested are marginal in flexion; several millimeters of socket wear will decrease the ROM. The results also emphasize the importance of proper component orientation at surgery. The surgeon has less latitude in orienting the components of a THR with limited ROM. Subluxation and dislocation due to rim contact can be minimized with most prosthetic units by instructing the patients to abduct and/or externally rotate their hips during acute flexion. Analyses suggest that impingement of prosthesis neck and socket rim may lead to increased risk of dislocation and increased rim wear. Prostheses with adequate ROM for everyday activities should provide stability, less frequent neck and socket contact with decreased rim wear, less force transmission to acrylic-bone interface, and less diminution of ROM with wear of the socket wall.
Hip Joint↗
Knee morphology as a guide to knee replacement.
The complexity of knee geometry requires correct prosthesis design and size selection for the recipient. This study analyzes the morphological relationships within the knee; 16 linear anatomical parameters were measured on 30 cadaveric knees. The marginal femoral condylar contour was geometrically described by two tangent radii. Standardized radiographic techniques were developed to obtain a modified tunnel and true lateral view of the knee. Subsequently, X-rays were taken from 11 cadaver knees to achieve reproducible magnification factors. From X-rays of 53 normal subjects, 11 comparable linear dimensions were measured. The linear dimensions and condylar contour measurements were analyzed for their interrelationships by computer techniques. The width of the femur was found to be dimensionally related (correlation coefficient significant at the one per cent level) to the measured parameters with the exception of the intercondylar notch and interspinous widths. Using regression analysis, nomograms were developed to predict the linear and marginal femoral contour dimensions from the femur width. The resulting standard deviations were low, ranging from 1.0 mm for ascertaining the tibial width to 3.5 mm for determination of the femoral width at the level of the intercondylar notch. The nomograms we developed will aid the surgeon in a more precise, preoperative, morphological evaluation and may be used as a guide for future knee prosthesis design.
Anthropometry↗
Pontic design and localized ridge augmentation in fixed partial denture design.
The endpoint of fixed prosthesis design is an esthetic and functional pontic that is compatible with soft-tissue health. In the posterior segment, where esthetics is not as critical, a sanitary pontic form is most compatible with function and hygiene. In the maxillary anterior region, a properly contoured modified ridge-lap pontic design constructed of glazed porcelain most readily fulfills both the esthetic and physiologic requirements. Although the ovate pontic form may satisfy esthetic demands to a greater degree, this is often at the expense of underlying soft-tissue health. In maxillary edentulous regions, ridge deformities may preclude a good pontic fit and esthetic result and dictate the need for surgical augmentation of the collapsed ridge. Selection of the appropriate surgical procedure and graft material depends on the nature and extent of the defect and availability of donor tissue. The subepithelial graft employing the tunnel approach is appropriate when augmentation in only a labial dimension is necessary. When the employing the trapdoor approach or full thickness gingival onlay graft may be employed. In large defects, sequential grafting procedures may be necessary to achieve the desired result. An esthetic and functional result can be attained through proper execution of an appropriate surgical technique and adherence to the principles of proper pontic design.
Alveolar Ridge Augmentation↗
Design of intramedullary prostheses to prevent bone loss: predictions based on damage-stimulated remodelling.
The adaptation of bone around intramedullary fixated prostheses, such as the femoral component of the hip joint or the radial component of the elbow joint, is well documented in follow-up studies. Bone adaptation takes the form of proximal bone atrophy accompanied, in some cases, by distal bone hypertrophy. A mechanistic model has been formulated to predict bone adaptation based on the concept that the continuous processes of damage and repair regulate bone adaptation. We apply the model to investigate the significance of two features of intramedullary prosthesis design on bone adaptation: prosthesis Young's modulus and the presence of a prosthesis collar. Results, as well, as indicating some characteristics of accumulative-damage stimulated bone adaptation, predict that a low Young's modules stem will very much reduce the extent of bone loss whereas the presence of a collar will have no significant effect. The results predict that a collarless low stiffness prosthesis is one possible approach for improving the secondary stability of intramedullary-fixated orthopaedic implants.
Adaptation, Physiological↗
[St. George's model of total elbow-joint prosthesis].
The elbow-prosthesis, design St. George, a hinge prosthesis is developed according to the principle of the Low Friction Arthroplasty. Only small resection of the joint is necessary so that in the "second line of defence" a resection-arthroplasty of elbow is possible. The experiences on 44 implanted prosthesis and the results of 37 cases are described. Restriction of motion, pain, instability and ankylosis in case of rheumatiod arthritis and posttraumatic arthrosis were the main indications.
Adult↗
Comparison of an EMG-controlled prosthesis and the normal human biceps brachii muscle.
An electromyographically-controlled elbow prosthesis, the "Boston arm", was tested with constant and sinusoidally-modulated inputs under different loading conditions. These tests were used to determine the frequency response of the EMG amplifier, the range of motor speeds, the force-velocity curve, and the frequency response of the prosthesis for cyclic movements. Human biceps muscle was tested during movements under similar loads, and under isometric conditions using random, electrical stimuli to determine its frequency response. The results were compared to evaluate the performance of the prosthesis and contrast its characteristics to those of the physiological system it replaces. The prosthesis minimizes quiescent power drain, and the possibilities of instability or "tremor" by employing velocity control, an overdamped mechanical system, and an electrical "dead-band". These factors limit the ability of the prosthesis to follow rapidly changing inputs or to move rapidly and accurately to a desired position. These comparisons should provide a useful supplement to the usual clinical evaluations, and a starting point for further improvements in prosthesis design.
Arm↗
[Reconstruction prosthesis after upper epiphyseal and diaphyseal resection of the femur for tumor. Results of 16 cases and a biomechanical study].
The authors have treated 16 cases of tumours of the upper end of the femur by resection over at least 12 centimetres and insertion of a massive prosthesis. The tumour was secondary in 9 cases and primary in 7. This treatment was used for metastases where conservative surgery was impossible or had failed. In primary tumours, when the excision was very extensive, the main problem was of stability of the prosthesis and its long-term future. A new type of total massive prosthesis, designed by the authors after biomechanical studies, is described.
Biomechanical Phenomena↗
Functional evaluation of patients fitted with total knee prostheses.
Degenerative or inflammatory diseases of the knee joint account for a large proportion of diseases affecting the elderly. Treatment aims to eliminate pain, correct the deformity and maintain complete joint mobility. In cases of total joint degeneration, fitting of a joint prosthesis is the technique currently favoured since elimination of pain and correction of the deformity, accompanied by recovery of joint mobility (the fundamental requirements for normal everyday life) can only be obtained if the knee joint is completely replaced. With the discovery of new materials and increasingly sophisticated knowledge about articular mechanics, the knee prosthesis, although more recent than the hip prosthesis, has become ever more widespread to the point that it now represents an irreplaceable aid in the treatment of this common disease. The clinical results obtained are already stable and particularly encouraging and prosthesis design is sophisticated and accurate. There is, however, still the suspicion that current prostheses can be considered "rudimentary" in comparison with the physiological and biomechanical behaviour of the human joint. We therefore wanted to begin an evaluation using a gait analysis system to assess patients fitted with knee prostheses. The first impressions gained in this study are the subject of this article.
Activities of Daily Living↗