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Biomedical subjects

D Wolter

Publications and source records attributed to D Wolter.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Autologous spongiosaplasty in the treatment of chronic osteomyelitis].

The most promising method of filling up osteomyelitic bone deficiencies is the transplantation of fresh autologous spongiosa as soon as the infection is under control. The fundamental principles of surgical therapy of septic focuses must not be neglected. A spongiosa graft into the florid infection has only little chances of success. The stability of the deficiency is decisive for the success of the transplantation. In case of infection it is necessary as far as possible to choose a point remote from the septic focus for the grafting of the osteosynthetic material.

Adult↗
PubMed1986

[Regression trends of neurologic damage in the surgical emergency management of patients with injuries of the cervical vertebrae with spinal cord involvement].

Sixty-five patients with cervical spine injuries and varied neurological deficits were treated operatively. Evaluation revealed an improvement in neurological findings dependent upon the promptness of anatomical reduction in patients with incomplete lesions. The more frequent neurological improvement seen with open reduction and internal fixation as compared with closed reduction was not statistically significant but was felt to justify the additional resources required for internal fixation. In complete lesions, there was no evidence that the time of anatomical reduction was related to improvement in neurological findings.

Adult↗
PubMed1983

The influence of various carbon fibre braiding techniques and methods of fixation on the extensibility of ligament prostheses.

An alloplastic ligament prosthesis with carbon fibres should not only be biocompatible but should also restore the biomechanical function of a natural system, which includes restoring its elasticity. Tests with new types of braided carbon fibre strands showed their elastic extensibility to increase with increasing number of filament tows and increasing braid angle. The best results were obtained with 32 tows and a 43 degrees braid angle. This strand type was tested in vitro as a medial collateral ligament prosthesis with two methods of fixation in human knees and, in like manner, in vivo in sheep knees. Biomechanical tests in vitro using human cadaver knees and sheep knees after 12 weeks' implantation showed an elasticity similar to that of normal natural ligaments.

Animals↗
PubMed1983

Biocompatibility of carbon fibre and carbon fibre microparticles.

Carbon fibres are integrated by the organism without causing significant foreign body reaction, but even with normal tissue growth around and encasement of the individual fibres. However, integration of the fibres into the tissue is not as good when the fibres are coated with epoxy-resin. Within the course of several months, progressive rupturing of fibres occurs with implants of pure carbon fibres, but with the mechanical function, however, being taken over by the formation of a connective tissue structure resembling a ligament. Carbon fibre microparticles are absorbed either by macrophages or by foreign body giant-cells and are distributed throughout the organism via the lymphatic system. Through these animal experiments--and also by studying the fate of an implant in a human being,--the biocompatibility of carbon fibres in the form of long fibres as well as in the form of microparticles can be judged as being excellent.

Animals↗
PubMed1981

The body reaction to carbon fibre particles implanted into the medullary space of rabbits.

It is thought that abrasion particles can produce a tissue reaction when alloplastic material is used for prosthetic devices. Therefore it is important to examine the reaction of the tissues and the body to microparticles before introducing a new material. Carbon reinforced carbon is a new material which is suitable for artificial joints because of its physical properties (strength and elasticity). Carbon fibre fragments with a diameter of 7 microns and a length between 20-100 microns were injected in the medullary canal of 16 rabbits, and evaluated after periods of 2 and 12 weeks. Phagocytosis of small carbon fibre fragments by macrophages occurs, but only a minimal foreign body reaction to the intramedullary carbon fibre fragments. There is a small amount of fibrosis around some carbon fibres and a small amount of new bone formation with inclusion of carbon. Only a few carbon fragments are transported to the parenchymal organs. There is no foreign body reaction.

Animals↗
PubMed1980

[Long-term observation after implantation of a carbon fiber-reinforced carbon hip joint endoprosthesis in foxhounds (author's transl)].

A hip-joint endoprosthesis, comprising a carbon fiber-reinforced stem, aluminum oxide head, and polyethylene acetabular cup, was studied in vivo trials in ten foxhounds after implantation with bone cement. Observations over 6 months and 1 year demonstrated that carbon fiber-reinforced carbon exhibits adequate strength for use as a stem material under the observed conditions.

Animals↗
PubMed1980

[The use of carbon fiber strands for replacement of collateral ligaments at the knee joint (author's transl)].

Two different anchorage systems of carbon fiber strands were tested on 16 human cadaver knees. To pull the C-strands out of the scale and channel anchorage almost the same force was necessary as to break the natural collateral ligaments. The ingrowth of connective tissues and newly formed bone around the C-fibers was studied in 11 sheep. A biomechanical strength test revealed, 3 months after implantation, a 60% strength compared to the natural ligaments. Histologically a C-fiber connective tissue composite with collagen fibers was found. Newly formed bone closely surrounded the carbon. These results indicate that carbon fiber strands are suitable for ligament replacement, which allows early joint motion. Good long-term results could be assumed as a result of the high biocompatibility.

Biomechanical Phenomena↗
PubMed1979

[Plastic replacement of the abdominal wall by uncoated carbon cloth. An animal experiment on the rabbit (author's transl)].

Carbon cloth is a new biomaterial which is suitable for the replacement of ligaments and connective tissues, because of its biological and physical properties. In 30 rabbits a defect was cut into the abdominal wall. In 20 the defect was covered by an implanted carbon cloth. The other 10 animals were used as controls. After implantation wound healing was excellent. No herniation could be observed in the group with the implants. After 3 months histological examinations revealed the ingrowth of collagen fibres into the carbon cloth. It had become a strong and resilient abdominal wall replacement. A physical-strength test showed stability of the newly formed abdominal wall with good anchorage to normal tissue.

Abdominal Muscles↗
PubMed1979

[Studies on the intra-osseous fastening of alloplastic ligament substitutes in sheep using carbon fibers].

The alloplastic replacement of the medial collateral ligament of the knee of sheep by carbon fibers gave a strength comparable with the natural ligament. Coating of the fibers, e.g., with epoxy resin, leads to a reduced integration of the implant into the tissues. Physical and histologic results together with the intraosseus anchorage show that pure carbon fibers are a suitable material for alloplastic ligament replacement.

Animals↗
PubMed1979

Fractionation of outdated freeze-dried plasma: a comparative study of cold- and heat-ethanol fractionation procedures.

In a comparative study a total volume of 1435 kg outdated freeze-dried plasma, equivalent to approx. 200,000 kg liquid plasma, was fractionated into albumin (20%): about 30% of the total plasma volume was fractionated following the cold-ethanol procedure and about 70% following the heat-ethanol method. Average albumin recovery following cold-ethanol preparation was 47% of the albumin originally present in the freeze-dried plasma (= 50% of total protein); following heat-ethanol fractionation, 71%. Gelfiltration of heat-ethanol albumin showed a main peak (= 93%) representing albumin monomers and one slightly faster component (= 7%) representing albumin dimers. Gelfiltration of cold-ethanol isolated albumin on the other hand showed four peaks: albumin monomers (= 60%), albumin dimers (= 15%), and two other peaks representing higher molecular weight molecules (= 25%). Hemoglobin present in the reconstituted plasma was reduced about five-fold in the cold-ethanol product and about ten-fold in the heat-ethanol albumin. Stability tests of both products did not differ from equivalent products isolated from normal human plasma. Besides albumin, immunoglobulins may be isolated as Cohn fraction II-III prior to the heating procedure without significant albumin loss.

Blood Banks↗