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Biomedical subjects

R Neugebauer

Publications and source records attributed to R Neugebauer.

At least 73 records · Page 4Linked to original sources
PubMed1983

Mechanical properties of ligament replacement with carbon fibres.

1. The tensile strength and modulus of elasticity of carbon fibres are comparable to those of stainless steel. 2. The small diameter (7-8 microns) produces high fibre flexibility, permitting braiding and weaving of this material. 3. The strength of braided ligament prostheses is about 2-3 times higher than the rupture strength of natural knee ligaments. 4. The elasticity and extensibility of a ligament prosthesis made of braided carbon fibres are higher than when there is a unidirectional arrangement. 5. The growth of connective tissue between the braided carbon fibres increases the elasticity and extensibility of the ligament replacement in vivo, so that 50-110% of the values for natural ligaments can be achieved. 6. The low shearing strength of the carbon fibres can be increased by a layer of collagen. 7. Intraosseous anchorages of the carbon fibre ligaments after 12 weeks of implantation exhibit strengths corresponding to 49-107% of the rupture strength of natural ligaments.

Animals↗
PubMed1983

The biological reaction of the tissues to carbon fibre ligament prosthesis in sheep-knees.

The biological reaction of the tissues to carbon fibre ligament prosthesis was examined in sheep knees. Connective tissue and bone grew into the alloplastic ligament at the insertion points in cancellous bone. There was tissue ingrowth around the carbon fibres intra- and extra-articularly. The bony ingrowth into the ligament increases with time and there was no resorption present. The carbon fibre ligament should not be used as an internal splint in the fresh ligamentous repairs. The easiest method of ligament replacement in a chronically unstable knee is the application of alloplastic ligament material. Therefore the search for a good substitute has never been given up. Carbon fibres are found to be a very good scaffolding and a permanent prosthesis for ligament replacement [1, 2, 6, 8]. The biocompatibility of carbon fibres in animals has been proved [4, 6, 7]. The mechanical properties, tensile strength and flexibility, make the fibres suitable for use as ligament substitutes. The braiding of carbon fibre bundles has improved its biomechanical properties [3]. In this study the biological reaction of sheep-knees to carbon implants is investigated: 1. Does connective tissue grow into the ligament prosthesis under physiological conditions? 2. Is there tissue growth around the carbon ligaments intraarticularly? 3. Is a C-ligament useful as an internal splint in fresh ligamentous repairs? 4. What is the fate of the bone-ligament interface in long term use?

Animals↗
PubMed1983

[Carbon fiber ligament replacement in the treatment of chronic instability of the external ankle joint ligament].

Ligament repair should be considered when a patient has disabling pain with giving way and chronic instability of the ankle from old ruptures of the lateral ligaments. Because of some incontestable disadvantages using Watson-Jones-or similar techniques we prefer the alloplastic with carbon fibres to reconstruct the anterior talofibular and calcaneofibular ligaments. Imitating the physiological course and insertions of the ligaments we managed to achieve a permanent lateral stability in 51 cases out of an operated group of 54 patients.

Ankle Injuries↗
PubMed1981

[Technique of the alloplastic ligament substitution with carbon fibres (author's transl)].

Chronic instabilities or remaining luxations of joints are not acceptable for an active human being. The desired result is often not achieved by surgical methods applying most different autologous and homologous materials. This is why our working group has been trying for several years to develop a more promising method using an alloplastic material in the form of carbon ligaments. Numerous mechanical, biological, biomechanical, and histological examinations showed that the implantation of woven carbon ligaments in man could be accepted. During the most recent years, we have effected 150 ligament grafts with this material and, in course of time, we have been able to modify and to ameliorate the operation techniques. Today we may state that the described operation methods using ligaments of carbon fibres in the sternoclavicular, acromioclavicular, knee and ankle joint can bring about favorable results with regard to their function and stability. Further improvements can probably be achieved by a careful examination of the results obtained hitherto which will possibly include another refinement of the operation technique. A definite evaluation of this method, however, will only be possible within several years, when clinical check-up examinations will be made.

Acromioclavicular Joint↗
PubMed1981

[Alloplastic grafting of ligaments with carbon-fibres (author's transl)].

During several years ligaments consisting of carbon-fibres have been tested in animal experiments. Recently this material was used in humans. Until today approximately 150 patients have been operated. The late results in 65 patients with instability in 66 joints are reported. Carbon-fibre-ligaments yielded good results, provided an expert surgical technic was applied and the follow-up care was optimal. Good results were achieved on the shoulder, the knee and the lateral ankle-joint. Initially there arose some problems due to technical difficulties. By using a modified surgical technic and improvements in the follow-up care still better results can be achieved. The present study is retrospective; a prospective study has been started.

Aftercare↗
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

[Closure of abdominal wall defects without tension using a carbon cloth implant (author's transl)].

On 20 rabbits a defect in the abdominal wall was closed by a carbon cloth (SIGRATEX KDS). A tensile force test and a histological examination was performed. Eleven days and 3 months after implantation, 10 animals with an operative-produced abdominal wall hernia and 10 normal animals were controls. A tensile force test on the specimen 3 months after implantation revealed a strength twice as high as on the normal abdominal wall. Eleven days after surgery the strength was equal to the scar tissue of the hernias. Histologically, a connective tissue ingrowth into the implant was observed, which enveloped the single carbon fibers. Collagen fibers in the direction of the carbon filaments were present. Foreign body giant cells were always seen. These results indicate that a carbon cloth seems to be suitable for the repair of abdominal wall hernias.

Abdominal Muscles↗
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↗