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Biomedical subjects

G Aldinger

Publications and source records attributed to G Aldinger.

At least 19 recordsLinked to original sources
PubMed2000

[Virtual simulation for optimizing the range of motion in hip alloarthroplasty using an adapted thrust-plate prosthesis model].

The purpose of the present study was to increase the free range of motion in conventional trust-plate prosthesis design and to optimize the trust-plate contact as well as the osteointegration area below the trust-plate. For the first part of the study, the two-dimensional geometry of the osteotomy plane was demonstrated in 25 CT-reconstructed femora after performing a virtual cut at a CCD angle of 135 degrees. In the second part, we constructed a prototype of an anatomic adapted trust-plate prosthesis (A-TPP) with an optimized trust-plate and corpus geometry based on the three-dimensional data of three human cadaveric femurs (age 67-75 years). In the final step, we documented the range of motion with computer-aided movement-mapping and compared the conventional TPP with the A-TPP. The results showed a wide variance in osteotomy geometry in the 12 femurs. With the A-TPP, we were able to obtain a much better fit in the trust plate surface. The movement-mapping showed a much higher range of motion in the A-TPP implant. With the A-TPP, the implant surface area for osteointegration could also be significantly increased.

Adolescent↗
PubMed1999

[Design features of an individual thrust plate prosthesis].

The purpose of the present study was to document the osteotomy plane for the thrust plate prosthesis, and to evaluate the question whether the geometry of the thrust plate itself correlates with the range of motion after implantation and whether the osteointegration area can be optimised. For the first part of the study, the two-dimensional geometry of the osteotomy was demonstrated in 12 computer-reconstructed femurs after performing a virtual cut at a CCD angle of 135 degrees. In the second part we constructed a prototype of an I-TPP with an optimised thrust plate and corpus geometry. In a final step, we documented the range of motion with computer-aided movement mapping. The results showed a wide variance in osteotomy geometry in the 12 femurs. With the I-TAP we were able to obtain a much better surface adaptation of the thrust plate. Movement mapping showed a much lower range of motion in the I-TPP implant.

Bone Plates↗
PubMed1991

Bone morphogenetic protein: a review.

The osteogenic potential of bone and bone matrix has been characterised only by its biological effects and the parameters influencing it. Recently, the osteoinductive ability of bone matrix had been defined chemically by the description of a bone morphogenetic protein (BMP), and the parameters of osteogenic factors from different species have now been recognised. The current state of isolation, purification and characterisation of these factors is summarised in this review. General aspects of the isolation and testing of BMP preparations, and the results of orthotopic application of BMP implants, including clinical cases, are reported.

Animals↗
PubMed1991

[3D-based production of hip joints: the Aldinger system].

Total hip replacement is regarded as one of the most successful surgical procedures. However, aseptic loosening of the foreign material still remains a great problem with endoprostheses. Bone cement, a material for filling and fitting, allows a solution to the problem in old people, but for younger people surgeons have looked for alternatives without cement. In fixation hip stems without form-filling cement, the greatest difficulty with standardized stems was the lack of adequate fit into the individual bone cavity. The new approach, the Aldinger custom-made hip stem, is based on a series of computer tomographical X-rays. This free-styled prosthesis stem is derived directly from the 3D-reconstruction of the inner contour of the femur without any parametrization of the cross-sections. A simulation of the implantation procedure is performed to ensure the implantability of the prosthesis and to give the surgeon some useful hints for the individual operation. In addition to the excellent form-fit to the individual bone, this prosthesis has further advantages such as the special disk-like surface structure, allowing good stress transfer to the bone, and the possibility of positioning the artificial head freely in three dimensions according to the requirements of therapy. Seven years of experience with this new system demonstrate that "computer-fit" can be a successful alternative to "cement-fit," especially in younger patients with a life expectancy of more than 10-15 years.

Equipment Design↗
PubMed1988

The personalized hip prosthesis.

The authors discuss the general concept, method of use and first clinical results obtained with a "personalized" femoral component of a hip arthroprosthesis based on the computer-graphic processing of measurements obtained from radiography and CT scan. This prosthesis is considered to be innovative as compared to traditional cementless prostheses.

Computer Graphics↗
PubMed1984

[Progress in endoprosthesis via computed tomography?].

A new procedure for the manufacture of endoprostheses with the aid of computer tomography is described. This modern radiological technique has not only revolutionised many diagnostic problems, but will also affect treatment intimately.

Joint Prosthesis↗
PubMed1983

Rare fracture of a total hip replacement.

Material fractures in the femoral part of total hip replacements, a late complication, are usually observed in the shaft. In our case, a fatigue fracture of the ball-neck weld occurred 8 1/2 years after implantation of the prosthesis because of insufficient weld depth. Additional negative factors proved to be varus implantation and overloading of the prosthesis due to obesity. The weld represented a point of low resistance. Even if major traumatic events are responsible for the fracture or loosening of an endoprosthesis, overloading (i.e., multiple "microtrauma") is also an important contributing factor.

Aged↗
PubMed1983

Computer-aided manufacture of individual endoprostheses. Preliminary communication.

Long-term anchorage of foreign material in vital bone has proven to be the main problem in endoprosthetics. In the authors' opinion, modelling an endoprosthetic anchorage component to the individual anatomic needs is, at present, the best way to transmit stresses harmoniously from the prosthesis to the sensitive bone, in order to utilize functional adaptation, and to guarantee long-term function. The production of a true-to-scale joint model is possible with computer-assisted tomography. This model of the joint or bone canal can be used to construct an individual endoprosthesis prior to surgery. A procedure described.

Biomechanical Phenomena↗
PubMed1983

[Alternative to plaster cast bandage of the thigh].

Immobilization by means of a femoral plaster-cast box cannot always cope with the wide variety and severity of the injuries and diseases in the knee-joint region. To achieve best possible rehabilitation, several alternative and subsequent methods of surgical bandaging are described, including indications, technique and pros and cons.

Bandages↗
PubMed1982

Aseptic loosening of cement-anchored total hip replacements.

The special conditions contributing to the loosening of 61 hip prostheses were studied and compared with 325 clinical and roentgenologically intact total hip replacements. The loosening rate rose sharply after the 6th postoperative year. One third of the artificial joints examined showed signs of loosening after the 9th year. The average loosening rate was 15.8% after 5.8 years. The condition of the bony bed apparently plays an important role, both qualitatively and quantitatively, in the success of the implant. The operative procedure is of equal importance. Deep fraising of the acetabulum, removal of insufficient amounts of cancellous bone from the proximal femur and inadequate embedding of the prosthesis stem, implantation of the stem in varus, and the use of long-neck femoral head prostheses are all factors which increase the risk of loosening. Ultimately, it is the sum of these loosening factors including the biological reaction of the tissue to the biomechanical and biochemically active foreign body which, depending on the period of influence, leads to prosthesis loosening. It is imperative that the patient's lifestyle be adjusted accordingly since external weight-bearing stress also affects durability of the prosthesis.

Aged↗
PubMed1981

[Medium-term results of osteotomy near the knee joint in the treatment of gonarthrosis (author's transl)].

271 osteotomies near the knee joint were performed between 1968 and 1977 at the Orthopedic Clinic of Tübingen University. The article reports on the results obtained in 69 patients who had been osteotomized because of gonarthrosis, out of a total of 135 patients, the results being evaluated after an average period of 4.9 years following the operation. The majority of these cases represented severe gonarthrosis. Indication, aim, planning and execution of the osteotomies performed near the knee joint, are discussed. Whereas angle plates are required in supracondylous osteotomy, clamps are sufficient in high supratubercular osteotomy of the tibia. In most cases it will not be necessary to perform more complicated osteosyntheses. The reasons are explained. In two-third to three-quarters of the cases, subjective improvement of complaints improved walking performance and standing ability are achieved. The relatively high incidence of complications is discussed.

Adult↗
PubMed1976

Psychiatric sequelae of phencyclidine abuse.

Phencyclidine use has been noted to produce a psychosis of several week's duration in a small fraction of users. Descriptions of the premorbid personalities of those who became psychotic resemble descriptions of LSD and marijuana users who experienced prolonged psychiatric difficulty. In addition, the psychosis produced can often be recognized as a "hallucinogen" psychosis. Certain features of the phencyclidine psychosis, namely the neurologic abnormalities, dose-related severity of symptoms, and regularity of the length of illness, are not noted with other psychedelic drugs, leading to the conclusion that PCP psychosis is a drug effect rather than a brief functional psychosis precipitated by the disintegrating PCP experience. However, the infrequent occurrence of psychosis in the (apparently) large exposed population still suggests that this is a combination of drug effect and vulnerable, pathologic personality.

Adolescent↗
PubMedDate not supplied

[Fundamental aspects of osteoinductive activity of bone tissue and potential clinical application].

Osteoinductive polypeptide factors such as the various isoforms of Bone Morphogenetic Protein described are of increasing scientific and clinical interest because of the great progress in this field of skeletal biology recently achieved. In a review some fundamental chemical and biological aspects of bone and its endogenous osteoinductive activity including isolation and assay of osteoinductive factors are described. Through combination of osteoinductive factors with appropriate carrier materials it seems possible to create osteoinductive implant materials and the results of such investigations and some basic aspects of carrier materials are summarized. The perspectives of the possible clinical applications of such composite are presented.

Biocompatible Materials↗
PubMedDate not supplied

[Computer assisted production of individual anatomic endoprostheses].

Long-term anchorage of foreign material in vital bone has proven to be the main problem in endoprosthetics. In the authors opinion, modelling of an individual anatomic anchorange component is, at present, the best way to transmit stresses harmoniously in order to utilize functional adaptation of bone and to attain long-term function. The production of a true-to-scale joint model is possible with computer-assisted-tomography. This model of a joint surface or bone canal can be used to construct an individual endoprosthesis prior to surgery. Our procedure of manifactoring a hip stem and a knee-surface-prosthesis is described.

Computers↗
PubMedDate not supplied

[The Freeman-Sheldon Syndrome].

Freeman-Sheldon syndrome (FSS) or craniocarpotarsal dysplasia is characterized by a triad of symptoms: 1. Masklike, whistling facial expression (whistling face syndrome), 2. Ulnar deviation of digits II to V and adduction contracture of the thumb and 3. Foot deformities. The pathogenesis of this malformation is unknown. Heredity is autosomal dominant and not sex-linked. Genetic counseling of affected individuals is imperative. The differential diagnosis should exclude the possibility of arthrogryposis multiplex congenita and particularly congenital windmill deformity of the fingers, which can also be accompanied by foot deformities. The foot and hand deformities associated with FSS are resistant to treatment and require consistent conservative and operative measures. Multiple, extensive operative interventions were unavoidable in both cases described.

Abnormalities, Multiple↗
PubMedDate not supplied

[Experience with Baycast plastic bandages and their possibilities].

A new method of manufacturing temporary orthoses is described. Immobilization--as much as necessary and as little as possible--is attainable with these orthoses, which reduce damage by immobilization and simplify rehabilitation. Recommendation to the manufacture regarding the characteristics of the material and accessory aids are presented.

Casts, Surgical↗