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At least 109 records · Page 6Linked to original sources
PubMed1996

Outcome of total hip arthroplasties with cement. Results after implantation of the Harris Design 2 prosthesis, 1983-1985.

Most reports of excellent long-term results of cemented total hip arthroplasty originate from studies of Charnley prostheses. A radiographic and clinical study was performed on 126 patients who underwent a cemented total hip arthroplasty from 1983 to 1985 with the Harris Design 2 prosthesis (Howmedica, Rutherford, NJ). The femoral component was cobalt-chromium and it had a broad, rounded medial border and a collar. The head diameter was 26 mm. A cemented all-polyethylene socket was used in all cases. At the last follow-up examination, 71% of the patients were completely free of pain and no patient had severe pain or pain at rest. Kaplan-Meier survival analysis estimated the revision rate at 10 years after operation to be 5 +/- 2% (mean +/- SEM) (including planned revisions). The rate of complete acetabular demarcation was 20% at 10 years, and femoral demarcation involving more than 50% of the bone-implant surface or endosteal cavitation was noted in only three cases. These results are as good as the best reported after total hip arthroplasty with the Charnley prosthesis.

Adult↗
PubMed1999

Total knee replacement: should it be cemented or hybrid?

OBJECTIVE: To compare the complication rates associated with total knee arthroplasty against the types of fixation (hybrid or cemented), using a single total knee design (the anatomic modular knee [AMK] prosthesis). DESIGN: A prospective, nonrandomized, controlled trial. SETTING: University Hospital in London, Ont., a tertiary care teaching centre. PATIENTS: Two groups made up of 484 knees in 395 patients (89 bilateral). INTERVENTIONS: In 260 knees a hybrid configuration (cemented tibia and noncemented femur) was used (group 1). In 224 knees the femoral and tibial components were cemented (group 2). All patellae were cemented in both groups. MAIN OUTCOME MEASURES: Clinical results were assessed by The Knee Society Clinical Rating Scores at 3 months, 6 months and yearly intervals. Radiographic results were determined by 3-foot standing radiographs and at each follow-up visit standing knee radiographs, lateral and skyline views. Radiographs were analysed for alignment, presence or absence of radiolucent lines or changes in the position of the implant. All reoperations and nonoperative complications were recorded. RESULTS: At an average follow-up of 4.8 years, 8 knees (1.6%) required reoperation. An analysis of the complications leading to reoperation demonstrated no difference between the 2 groups. CONCLUSIONS: There was no difference in outcome whether the femoral component was cemented or not. Medium-term results of the AMK are excellent with a very low reoperation rate.

Aged↗
PubMed1988

The cross-linking and structure modification of the collagen matrix in the design of cardiovascular prosthesis.

Glutaraldehyde cross-linking of native or reconstituted collagen fibrils and tissues rich in collagen significantly reduces biodegradation. Other aldehydes are less efficient than glutaraldehyde in generating chemically, biologically, and thermally stable cross-links. Implants of collagenous materials cross-linked with glutaraldehyde are subject long-term to calcification, biodegradation, and low-grade immune reactions. We have attempted to overcome these problems by enhancing cross-linking through (a) bridging of activated carboxyl groups with diamines and (b) using glutaraldehyde to cross-link the epsilon-NH2 groups in collagen and the unreacted amines introduced by aliphatic dismines. This cross-linking reduces tissue degradation and nearly eliminates humoral antibody induction. Covalent binding of diphosphonates, specifically 3-amino-1-hydroxypopane-1, 1-diphosphonic acid (3-APD), and to a lesser extent chondroitin sulfate to collagen or to the cross-ling-enhanced collagen network reduces its potential for calcification. Platelet aggregation also is reduced by glutaraldehyde cross-linking and nearly eliminated by the covalent binding of chondroitin sulfate to collagen. The cytotoxicity of residual glutaraldehyde can be minimized by chemical neutralization and thorough rough rinsing.

Adenosine Diphosphate↗
PubMed1987

An alternative design of extension prosthesis.

Some patients with a congenitally shortened lower limb can be fitted with a total contact socket of one piece construction, dispensing with the need for removable panels or split socket construction. This gives advantages in weight, strength and cosmesis. The technique is described and compared with those conventionally used.

Artificial Limbs↗
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↗
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↗
PubMed1993

[The bi-contact endoprosthesis system--intermediate results of five years use].

The Bicontact endoprosthesis system has been used in our hospital with almost 1800 patients since 1987 for the treatment of painful destructive conditions of the hip joint, the proportion of traumatic subsequent conditions being 20%. It is a modular system that can be used with the same instruments for cementless and cemented fixation. The medium-term results of follow-up examinations over 5 years show that the biomechanical concept is correct. No aseptic loosening of the stem of prostheses has been reported to date, and it has not been necessary to change the prosthesis design. The femoral pain observed in the case of many other shaft prostheses implanted without cement has not been experienced owing to a particularly high rotational stability of the Bicontact shaft. The good results obtained in the meantime have led to an increase in the range of available models(dysplasia prosthesis). Work is progressing on the development of a revision prosthesis based on the biomechanical fixation principles of the Bicontact system.

Adult↗
PubMedDate not supplied

Semibiologic middle ear prostheses: ossicle cup and ossicle columella.

As a natural step in ossicular reconstruction technique, two semibiologic prostheses are introduced. The prosthesis designed for incus replacement is called the "ossicle cup." A hole is drilled in the body of an incus or head of the malleus, and the synthetic shaft of the ossicle cup is placed into the hole. The synthetic cup fits over the stapes capitulum, forming a joint. The ossicle keeps the synthetic portion from touching the tympanic membrane. The prosthesis designed for total ossicular replacement is called the "ossicle columella." In like manner, the shaft is inserted into a shaped ossicle and placed on the remaining footplate. The ossicle columella has a synthetic footplate that rests on the remaining footplate and provides stability and safety. The adaptability of the semibiologic prostheses solves the problems of a laterally healed tympanic membrane, absent stapes capitulum, remaining footplate crura, low-lying stapes, and retracted malleus. The hearing results of the ossicle cup prosthesis indicate 87% of cases with successful hearing at one year. The ossicle columella results in 71% of cases with successful hearing at one year. To date, the extrusion rate is less than 1%.

Bioprosthesis↗
PubMed1989

[What should be the shape of extracardiac conduits?].

Studies of the hemodynamic features of the blood flow in extracardiac conduits allow for a grounded and aimed approach to the prosthesis design. The lack of interrelationship between the duct geometry, the flow pattern, and the heart anatomy is one of the reasons for the existing conduits inadequacy. Here is proposed a confuser conduit model providing a stable uninterrupted flow. Development of a hemodynamically optimal type-size series of conduits would allow one to reduce the incidence of complications resulting from inadequate prosthesis design.

Equipment Design↗