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Biomedical subjects

T Albrektsson

Publications and source records attributed to T Albrektsson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Acute tissue reactions to potassium alginate with and without colour/flavour additives.

The acute tissue reactions to potassium alginate, locally applied to a microvascular bed, were studied with the use of the vital microscopic hamster cheek pouch model combined with correlative histology. This experimental model permitted us to study microvascular permeability, blood flow, vessel diameters and leucocyte adhesion to vessel walls intravitally, and leucocyte migration and mastcell degranulation histologically. Deionized water alone and potassium alginate with flavour and colour mixed in saline was found to cause severe microvascular alterations, while potassium alginate, without flavour and colour, but mixed in saline and applied to the microvasculature resulted in a minor inflammatory reaction.

Alginates↗
PubMed1987

Present clinical applications of osseointegrated percutaneous implants.

Altogether, 389 screws of commercially pure titanium have been inserted at various locations in the facial skeleton of 174 patients. The indications for treatment have been stable anchorage of an external hearing aid or a facial episthesis, in the latter case to restore the facial contours after congenital disorders or status after trauma or cancer surgery. All implants have been inserted in a two-stage procedure, the first being anchorage of the titanium elements in the bone, the second, minimally 3 months later, being establishment of a permanent skin penetration. The outcome of every inserted implant has been analyzed. Only six implants failed to become integrated in bone and had to be removed. Five of these failures occurred in previously irradiated bone, where the success rate was estimated to 85.3 percent. In nonirradiated bone, 354 of 355 inserted implants became osseointegrated, i.e., anchored in bone in a stable manner. The soft tissues were without any adverse reactions in 92 percent of the 951 clinical observations, whereas potentially serious skin complications were observed in only 2.8 percent. Presently, the longest clinical follow-up is 8 years, and 37 implants have been followed for more than 5 years. We believe that this clinical material is the first in which an uneventful bone anchorage and skin penetration have been demonstrated in consecutively operated upon clinical cases. The implants used for anchoring an external hearing aid were also successful in the sense that the patients gained 15 dB (average) in hearing threshold and showed a significantly improved discrimination score. The implants inserted to hold facial epistheses resulted in considerably improved retention and a good cosmetic outcome for the patients.

Bone Screws↗
PubMed1987

Edentulousness--an oral handicap. Patient reactions to treatment with jawbone-anchored prostheses.

A questionnaire was sent to all 189 edentulous patients with denture adaptation problems who were treated with fixed prostheses on osseointegrated oral implants during the period 1965-1978. One hundred and fifty-two patients (80%) responded. Practically all had adapted well to the prostheses and were most satisfied with the rehabilitated oral function, including chewing ability. Four out of five patients regarded the bridge as part of their own body instead of a foreign object, and 90% would not hesitate to have the treatment performed again, if necessary. Parallel with the improved oral function the patients reported a definite reduction of psychosocial problems associated with their previous oral invalidity, and increased security and self-esteem.

Adult↗
PubMed1987

Soft tissue infection around a skin penetrating osseointegrated implant. A case report.

A case is reported where a female patient with bilateral otosclerosis received a bone-anchored and skin-penetrating titanium implant on which a hearing aid was mounted to improve conductive hearing loss. The patient developed an infection that did not cease despite intensive local treatment and skin-grafting. Eventually the implant was removed. The histological examination of the interface between implant and surrounding bone and soft tissues showed an inflammatory reaction in the superficial parts of the soft tissues whereas the deeper portions of the soft tissues and all of the bone tissue were free of inflammation. It is concluded that it is possible to maintain osseointegration in spite of an aggressive soft tissue infection around the implant.

Adult↗
PubMed1987

Titanium implants in the otic capsule: development of a new multichannel extracochlear implant.

Preliminary data are presented on the development of a new approach for multi-channel stimulation of the cochlea. The approach is based upon the use of small titanium implants in the lateral wall of the inner ear which act as anchor points for platinum-iridium stimulating electrodes. These holders allow contact of the stimulating electrode with the lateral surface of the membranous labyrinth. Observations in monkeys indicate that some degree of anchoring of the titanium implant in the otic capsule is achievable, including the formation of a close bone-metal interface. We propose that this approach may yield an alternative strategy for the development of a multichannel extracochlear prosthesis.

Animals↗
PubMed1986

The bone growth chamber for quantification of electrically induced osteogenesis.

A dividable titanium implant was inserted in the tibial metaphysis of rabbits, which permitted a numerical evaluation of ingrowing bone. The implant on the test side was used as cathode and was connected to a subcutaneously located stimulator delivering constant current of either 5 microA, 20 microA, or 50 microA. A corresponding control implant was inserted in the other tibia of the same animal and treated likewise, but was not connected to the stimulator. Distally to each implant, a platinum-iridium screw was inserted into the cortex and connected on the test side to the stimulator to serve as the anode. The results showed a 2.4-fold increase in bone formation with 5 microA. In the 20-microA group, there was 2.6-fold more bone in the test chambers. Direct current (DC) stimulation with 50 microA caused a clear decrease of bone volume, with an average of 48% less bone in the test implants. The results indicate that 5 and 20 microA direct current enhance bone ingrowth into a titanium implant that is used as a cathode. The osteogenesis seemed to be more pronounced in the case where the chamber was used as a cathode compared to earlier experiments in which the cathode was placed at a distance of 5 mm from the implant.

Animals↗
PubMed1986

Temporary bone tissue ischemia in the hind limb of the rabbit. A vital microscopic study.

With in situ bone vital microscopy it was demonstrated that a cuff pressure of 300 mm Hg applied over the rabbit thigh is sufficient to cause a complete vascular standstill in the tibial cortex. Cuff-induced tissue ischemia applied for 30 min did not result in any adverse bone tissue reactions over a follow-up period of 30 days. Locally applied isolated bone ischemia for 3 or 6h resulted in an inflammatory response, and 4-6 weeks after the 6-h ischemia bone resorption was evident.

Animals↗
PubMed1986

Bone marrow pressure chamber: a permanently inserted titanium implant for intramedullary pressure measurements.

We describe a titanium implant for repeated intramedullary pressure measurements. The implant has been inserted permanently in the tibia of rabbits. Pressure is transmitted through a membrane in the chamber to a transducer connected to a meter. During the recordings no penetration of the cortex is necessary. The measured intact intramedullary pressure in the tibia was approximately 12 cmH2O.

Animals↗
PubMed1986

An ultrastructural characterization of the interface between bone and sputtered titanium or stainless steel surfaces.

Experimental implants of polycarbonate covered with a thin metallic layer were inserted in the rabbit tibial metaphysis. The implants had either a magnetron sputtered 316 L stainless steel or commercially pure titanium surface (or an evaporated commercially pure titanium surface). The aim of the experiment was to investigate the interfacial arrangements between bone and the coatings used. Three months after implant insertion, the animals were sacrificed and the intact interface between bone and metal analysed using ultrastructural techniques. In the case of stainless steel a coat of 1-2 cellular layers separating the bone from the metal was found. Inflammatory cells were abundant as well as a wide proteoglycan coat lacking collagen filaments. In the case of titanium there were no cells in the interface which consisted instead of a proteoglycan layer of about 200-400 A width. Bundles of collagen appeared at a minimum distance of 1000-2000 A from the metal surface. Calcium deposits were sometimes seen in direct contact (resolution level 30-50 A) with the titanium oxide. There were no ultrastructural differences in tissue reactions when magnetron sputtered titanium surfaces were compared with evaporated ones.

Animals↗
PubMed1986

Metacarpophalangeal joint replacement with osseointegrated endoprostheses.

A new type of endoprosthesis for reconstruction of the metacarpophalangeal (MCP) joint has been tested. The novel arthroplasty consists of a joint mechanism with two screw-shaped fixtures for bone anchorage. These fixtures, of commercially pure titanium, are gently screwed into the anchoring bone on each side of the diseased joint, the aim being to achieve osseointegration, i.e. a direct contact between implant and bone without interposed soft tissue layers. The hand was immobilized in a dorsal splint for 8-10 days post-operatively after which a carefully controlled mobilization program was initiated. In principle, the titanium fixtures, the surgical technique and the primary immobilization represent an approach similar to that previously used in various reconstruction procedures of the jaw. This paper describes 5 case histories of reconstructions required because of osteoarthrosis in a single MCP joint. Prior to the operation, all patients suffered from severe problems resulting from their arthrotic joints and they had not been able to work for several months. After surgery they were evaluated by a clinical assessment program and X-rays were taken at various times of follow-up. As well as visual inspection all radiograms were subjected to densitometry by means of a computer-based image-analysis system in order to provide information on the development of bone density in the bone-to implant interface region. From a functional point of view the treatment with osseointegrated prostheses must be regarded as being successful. All patients were able to go back to their original work and their hands had a satisfactory range of movement and grip strength with no signs of impaired function on longer follow-up time. Clinical problems were one re-operation, one case of implant fracture and one case requiring exchange of the joint mechanism. The computer-assisted evaluation of the radiograms revealed the presence of calcified tissue in many sections where the naked eye was not capable of differentiating any bone. In conclusion, it seems possible to establish osseointegration of MCP-endoprostheses in the arthrotic human joint in complicated cases which were regarded as contraindicated for any other joint arthroplasty.

Bone Screws↗
PubMed1986

Osseointegration of titanium implants.

Forty-eight screws, six double cylindrical implants and six T-plates were inserted into the tibia or femur of 6 dogs. Two titanium screws were inserted into the proximal tibia of 5 patients to anchor a titanium mould. The implants were removed en bloc with adjacent bone tissue after 3 to 14 months. They were sectioned using a technique that allowed analysis of the intact tissue-to-metal specimens. Osseointegration, defined as a direct bone-to-implant contact without interposed soft tissue, was confirmed in all screw-shaped implants while the cylindres had only partial bone contact as did the T-plates. We conclude that osseointegrated implants may be applicable in joint reconstruction for arthrosis or rheumatoid arthritis.

Adult↗
PubMed1986

Osseointegrated dental implants.

Endosseous implants of commercially pure titanium have been demonstrated to give success rates of more than 90 per cent over 10 years of follow-up. This high level of clinical function depends on an implant direct anchorage in bone without any interposed soft tissue layers and on a reaction-free soft tissue surrounding the abutments. Provided a correct protocol is followed, such osseointegrated dental implants may be looked upon as a routine procedure in the treatment of edentulousness.

Biocompatible Materials↗
PubMed1985

Indomethacin, (-)-terbutaline (beta 2 agonist), and (+)-terbutaline in acute inflammation induced by repeated ischemia in hamster cheek pouch.

A mild and controlled acute inflammatory reaction in hamster cheek pouch was created without any exogenous, but rather by locally activated and liberated, mediators. A pressure of 60 mm Hg was applied to part of the everted cheek pouch eight times with a 10-min recovery period in between. The microvascular response was followed by intravital microscopy and the permeability changes were monitored with intravital fluoroscopy and intravenous FITC dextran (mol wt 150,000). The number of extravasated polymorphonuclear leukocytes (PMNLs) was calculated by a new, whole tissue, histological technique. In three experimental groups (-)-terbutaline (beta 2-receptor agonist) 0.05 mg/100 g body wt., (+)-terbutaline 0.05 mg/100 g body wt., and indomethacin 2 mg/100 g body wt. was given intravenously before pressure was applied. A fourth group, with no drug given, served as control. There was a rapid increase in the number of FITC dextran leakages and extravasated PMNLs in the control group. Indomethacin almost completely inhibited FITC dextran permeability and extravasation of PMNLs. The beta 2 agonist markedly diminished the number of FITC dextran leakages for 75 min. The number of extravasated PMNLs was also reduced. Treatment with (+)-terbutaline, which is supposed to have no beta 2-receptor effect, gave a slight reduction in number of FITC dextran leakages and almost a complete inhibition of PMNL extravasation. Thus we conclude that indomethacin is a very potent antiinflammatory agent even in the early phase of inflammation. (-)-Terbutaline diminished the inflammatory response, probably by preventing endothelial gap formation. (+)-Terbutaline prevented PMNL extravasation either by interaction with the PMNL itself or with the endothelium.

Animals↗
PubMed1985

Intraosseous transducers for hearing by bone conduction. Peroperative measurements.

Now that it is possible to establish and maintain a reaction free skin penetration, there are new prospects for hearing through bone conduction. Peroperative hearing threshold measurements on patients entering hospital for ear surgery under local anaesthesia have been made. An electromagnetic transducer was temporarily cemented into the cortex of the mastoid process and the transducer current for threshold signals at different frequencies recorded. Considerable variability was found between patients but a distinct common pattern from 0.25 kHz to 8 kHz could be identified in the audiograms. With the transducers used, the power consumption was found to be low (1 mW) at threshold levels but to achieve a comfortable hearing level the electrical power needed was found to be as high as 4W.

Auditory Threshold↗