Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Prosthesis Design”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1975

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↗
PubMed1994

[Studies of sound condition in the reconstructed middle ear with a hydrophone. Initial results].

The acoustic result following reconstruction of the middle ear is often disappointing and unpredictable. Apart from biologic factors, this is due to insufficient knowledge of the mechanism of sound transmission through the operated middle ear. Therefore, temporal bone experiments with simulated middle ear operations were set up to investigate the sound transmission following different prosthesis' designs, materials, etc. We developed a tiny hydrophone which has a frequency range from 100 Hz to 10 kHz in order to measure the sound pressure in the cochlear fluid. By comparing the sound pressure in the inner ear with the sound pressure at the drum membrane, we were able to analyze the transfer function of the manipulated middle ear. First results with different reconstruction techniques, prosthesis' designs and attachments demonstrated the usefulness of this measuring technique for the development of acoustically better middle ear reconstructions.

Bone Conduction↗
PubMed1996

Prosthetic rehabilitation after craniofacial surgery.

We report our experience during the last 6 years with 20 patients fitted with prosthesis (19 patients with osseointegration of screw, 1 patient with primarily gluing method) for camouflage of congenital or acquired (trauma, tumor resection) defects of the ear, nose, or eye. Out of a total of 53 extra-oral implants fitted, 3 were lost in the orbital area due to loosening 6 months after radiation treatment. Another three implants were removed at the request of an 80-year-old patient who preferred a prosthesis retained by spectacles because of recurring infection around one of the implants. On average, 43 months (range, 7 months to 8 years) after completion of the prosthesis, 85% of the patients assessed the result as excellent, 15% as good, 0% as fair, and 0% as poor. The ENT surgeon and the prosthesis designer were slightly more critical (ENT surgeon-95% good or excellent and 5% fair, prosthesis designer-90% good or excellent, 10% fair).

Journal Article↗
PubMed2005

[Dynamic loads at knee joint of trans-tibial amputee on different terrains].

Dynamic loads at knee joint of amputee are fundamental for rehabilitation of knee injury and prosthesis design. In this paper, a 3-D model for calculation of dynamic load at knee joint of trans-tibial amputee was developed. Gait analysis was done on three terrains including normal level walking, upstairs and downstairs. Dynamic loads at knee joint were calculated during one gait cycle. The results show that gait patterns and dynamic loads at knee joint were different among these three terrains. Although the general waveforms were about the same, the motion range of knee joint, ground reaction forces and loads at knee joint when walking upstairs or downstairs were larger than those in a normal level walking. The quantitative findings provide the theoretical basis of gait analysis and prosthesis design for trans-tibial amputee.

Amputation Stumps↗
PubMed2003

Adapting innovative motion-preserving technology to spinal surgical practice: what should we expect to happen?

STUDY DESIGN: A literature-based review of approach-related morbidity and a conjectural analysis of potential complications of disc arthroplasty based on experience with total joint arthroplasty. OBJECTIVE: To describe predictable complications of disc arthroplasty and possible strategies for minimizing or treating these complications. SUMMARY OF BACKGROUND DATA: There is a significant experience with anterior approach-related morbidity in spinal surgery. There is also extensive experience with extremity total joint arthroplasty. The combination of these experiences should predict certain occurrences that will occur with the advent of disc arthroplasty in the spine. METHODS: Review of the medical literature associated with anterior approach to the lumbar spine for spinal fusion was done. Sequential steps for performance of disc arthroplasty and possible problems with each step were evaluated and possible complications identified. Parallel experience in total joint arthroplasty was reviewed for possible predictive experience. RESULTS: There are definable approach-related morbidities that will occur, regardless of prosthesis design and implantation technique. Prosthesis design involves a series of tradeoffs for risks and benefits. Revisions are inevitable; rate of revision and time to revision remain to be determined. CONCLUSIONS: Disc arthroplasty will offer benefits over current fusion techniques. It will come at a cost and certain complications are entirely predictable. There will be deaths from the procedure, due to thromboembolic phenomenon or due to uncontrollable hemorrhage from irreparable vascular injury, especially on repeat operations. There will be prostheses that dislodge. There will be infections that require device removal, a very high-risk procedure. There will be a deterioration of results in the hands of the general medical community as opposed to the hands of the initial investigators, a learning curve if you will. The access surgeon will be critical to minimizing morbidity. Design considerations compete with anatomic constraints. Material choices all have pros and cons. Spine surgeons as a whole are excited about this opportunity, but we must be diligent to minimize these predictable adverse events to make the risk benefit profile the best that it can be for our patients.

Arthroplasty, Replacement↗
PubMedDate not supplied

A new prosthetic design for proximal humeral fractures: reconstructing the glenohumeral unit.

A new shoulder prosthesis design for proximal humeral fractures has been developed. The rim of the articular component of this prosthesis has several holes to which the bone-tendon junction of the rotator cuff is fixed, to allow an anatomic reconstruction of the glenohumeral unit. The strength of the tuberosity fixation to this prosthesis is investigated in a cadaveric study. Artificial 4-part fractures were created in 18 human, fresh-frozen, paired shoulder joints with intact rotator cuffs. Two methods of tuberosity fixation were used in a matched-pair fashion. In group I the tuberosities were sutured to the rim of the prosthetic head, and in group II the tuberosities were circumferentially tension band-wired. Strength testing was performed on a material-testing machine, and displacement was recorded with an opto-electronic device. Both fixation methods proved to be equally reliable in the forces exerted during activities of daily living without significant displacement of the fracture fragments.

Aged↗
PubMed2000

Fixed or removable implant-supported restorations in the edentulous maxilla: literature review.

Among the prosthesis designs used to treat the edentulous maxilla are fixed or removable implant-supported restorations. Since the aesthetic requirements and preoperative situation of each patient varies, controversy exists regarding prostheses' success rates and complications. The purpose of this article is to compare the treatment options and prosthesis designs with their indications and to compare implant and prosthesis success and treatment expense. This objective was accomplished through the review of reports with regard to varying design considerations and factors that influence the decision-making process and treatment outcomes.

Cementation↗
PubMed2004

[Endoprostheses of the knee joint].

Due to the advances in prosthesis design and standardisation of implant techniques, the maintenance of implants in arthroplasty of the knee joint has enormously increased during the past few years. Various arthroplastic designs enable an adjustment towards the patient's individual indiction and anatomy. For one-compartmental arthrosis, monocondylous prosthesis can be implanted using microinvasive operation techniques. Prerequisite for mere joint resurfacing is an intact lateral ligament apparatus, whereas the the symmetrical ligament balancing is essential for long-term analgesia, joint stability and good flexion. Aseptic loosening, discreet infections, instabilities and patellar problems are common reasons for painful knee arthroplastics.

Arthroplasty, Replacement, Knee↗
PubMed2003

[Total elbow arthroplasty in rheumatoid arthritis using GUEPAR prosthesis].

PURPOSE OF THE STUDY: We report a retrospective analysis of 16 patients with rheumatoid arthritis treated with a total humero-ulnar and humero-radial GUEPAR prosthesis (GIII). MATERIAL AND METHODS: The GUEPAR III elbow prosthesis is an anatomic polyethylene-metal gliding prosthesis designed to maintain physiological valgus. Right and left models are available in two sizes. On the humero-ulnar side of the prosthesis, was associated with a radial head, born on an intramedullary metallic stem, that can be fit with several sizes of mobile polyethylene cups. The 16 GIII prostheses were implanted in 1997 to 2001 in accordance with the manufacturers instructions. Mean follow-up was 2 years. RESULTS: Before surgical treatment, all patients had moderate or severe but invalidating pain. The Mayo Clinic score was 33 points. The Larsen radiographic score was grade III (7 elbows) or grade IV (9 elbows). Patients were reassessed 1 to 5 years after implantation of the GIII (mean follow-up 2 years). At last follow-up the mean Mayo Clinic score had improved from 33 to 90 points. Outcome was considered excellent for 15 elbows and fair for 1. DISCUSSION: We review the indications for total elbow arthroplasty in patients with rheumatoid arthritis. Semi-constrained prostheses are useful and necessary for the treatment of elbows exhibiting massive destruction, but the use of minimally constrained prostheses such as the GUEPAR III is becoming increasingly widespread. We use the GUEPAR III for 70% of our patients, particularly those with rheumatoid arthritis.

Adult↗
PubMedDate not supplied

[Endoprosthetic replacement of the shoulder joint. Possibilities and their analysis].

Functional and anatomic characteristics of the shoulder girdle are special problems, that have to be solved in the process of using an artificial joint replacement to improve the function of a painful shoulder, which is restricted in movement. Seen from a biomechanical point of view, besides a safe fixation of the prosthesis the stability and kinematic of the artificial joint are of considerable importance for the success of the endoprosthetic treatment. The efforts of meeting these requirements by a respective prosthesis design led to a variety of prosthesis types. This study shows the possibilities for prosthetic replacement of the shoulder joint and comprises an analysis of all systems, which are available on the market, as well as of the patent applications of the past 15 years. The prostheses are listed according to their stability. Relative to the state of destruction of the joint unconstrained prosthesis types with completely free and partially restricted mobility, as well as constrained types of joints are being discussed.

Biomechanical Phenomena↗
PubMed1980

Preliminary report on postoperative results of newly designed stable total knee prosthesis.

A newly designed stable total knee prosthesis was made for the severely destructed knee. This prosthesis was named the Yoshino total knee prosthesis, and is a non-hinged type prosthesis consisting of a vitallium femoral component and a ultra-high molecular weight polyethylene tibial component. Clinical results of 127 Yoshino total knee arthroplasties showed the following characteristics: 1) good stability, and 2) good mobility. Stability was exceptionally good, and the results were the same as the hinged total knee prosthesis.

Adult↗
PubMed1992

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↗
PubMed2005

Issues and considerations in dental implant occlusion: what do we know, and what do we need to find out?

Implant dentistry continues to struggle with what are the appropriate occlusal concept(s) for implant-supported restorations. The biological and mechanical consequences of the loading environment leads to establishing and maintaining an implant interface in a wide variety of bone quality and quantity, implant and prosthesis designs. To the restorative dentist, the role of occlusion is more focused on extending the service life of the restoration and the connecting abutment(s) than protecting the osseous integration of the implant(s). This study reviews the relevant issues regarding implant occlusion along with implant and prosthesis design in order to provide optimal patient care.

Animals↗
PubMed2001

Implant versus tooth-implant supported prostheses in the posterior maxilla: a 2-year report.

When implants are used for restoration of a jaw with a residual dentition, the possibility of combining implants with natural abutments may be considered. In a longitudinal comparative study, 26 patients (15 women & 11 men, age 49-84 years) with residual anterior dentitions were treated with two different designs of fixed partial dentures bilaterally in the posterior maxilla. On one side the reconstruction was supported by implants only, while on the contralateral side an implant and a tooth in combination were used. The patients were followed at intervals of 3, 6, 12 and 24 months after loading of the implants. 95 implants were placed, of which 11 non-loaded. A total of 10 implants failed, 7 prior to loading and three within the first three months of service (88.0+/-SE 6.7% cumulative survival for tested implants after two years' follow-up). There was no difference in failure rate for the implants in the two different prosthesis designs. The total mean loss of marginal bone height close to the implants was within acceptable standards, but was more pronounced at the implants not combined with teeth. The results indicate a correlation between the prosthesis design and the loss of marginal bone.

Aged↗
PubMed2000

Optimization of design and surgical positioning of inflatable penile prostheses.

The interaction between the cylinders of an inflatable penile prosthesis (IPP) and the surrounding tissues during IPP-aided erection may result in local elevated stresses. These stresses may reach values that can obstruct penile blood vessels and cause ischemia and/or stimulate nerves around the operation site, thereby inducing sensations of pain. A new numerical model was used to analyze penile stresses postimplantation of different IPP types, in order to optimize prosthesis design and surgical positioning by enabling minimal stress transfer to dorsal blood vessels and nerves. The results suggest that intraluminal pressures should be maintained at low levels (about 80 kPa) while cylinder thickness and stiffness should be kept just high enough (approximately 15% of the radius and 1000 MPa, respectively) to eliminate deleterious cylinder-tissue contact stresses. Smaller prosthetic cylinders, i.e., occupying about 45% of the cavernosal space, may be advantageous in terms of reducing dorsal stresses, but lower penile rigidity should be expected. A significant decrease of dorsal stresses can also be achieved by encouraging the surgeon to position the cylinders toward the lower part of the corpora. The numerical simulations indicate that circular cylinders may allow greater biomechanical compatibility of the IPP with the penis structure than elliptic ones, and this should be a subject for clinical investigations.

Biomechanical Phenomena↗
PubMed2001

A novel low wearing differential hardness, ceramic-on-metal hip joint prosthesis.

Osteolysis and loosening of artificial joints caused by polyethylene wear debris has prompted renewed interest in alternative bearing materials for hip prosthesis designs. Lower wearing metal-on-metal (MOM) and ceramic-on-ceramic prostheses are being used more extensively, and there is considerable interest in further improving on their performance. This study investigated the wear properties and debris morphology of a novel differential hardness ceramic-on-metal (COM) prosthesis, in comparison with MOM articulations in a physiological anatomical hip joint simulator. The COM pairings were found to have wear rates approximately 100-fold lower than the MOM pairings. The MOM pairings showed a higher "bedding in" wear rate (3.09+/-0.46mm(3)/10(6) cycles) in the first million cycles, which then reduced to a steady state wear rate of 1.23+/-0.5mm(3)/10(6) cycles. The wear rate of the COM pairings over the duration of the test was approximately 0.01mm(3)/10(6) cycles with very little wear detected on the surface of the prosthesis components. The wear particles from both articulations were oval to round in shape and in the nanometer size range. After one million cycles the mean maximum diameter of the MOM and COM wear particles were 30+/-2.25 and 17.57+/-1.37nm, respectively. After five million cycles the wear particles were statistically significantly smaller than at one million cycles, 13.9+/-0.72nm for the MOM pairings and 6.11+/-0.40nm for the COM pairings. The wear rates of the MOM prostheses were representative of clinical values. The use of differential hardness COM pairings dramatically reduced the wear rate compared to MOM hip prostheses. The wear particles from the MOM articulation were similar to particles found in retrieved tissues from around MOM prostheses. The extremely low wearing differential hardness COM bearings presented in this study produced far smaller volumetric particle loads compared to MOM prostheses currently used clinically.

Biocompatible Materials↗