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Biomedical subjects

M Jacobsson

Publications and source records attributed to M Jacobsson.

35 records · Page 2Linked to original sources
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

Bone cell viability after irradiation. An enzyme histochemical study.

Adult rabbits were irradiated to one proximal tibial metaphysis while the contralateral tibia served as a control. Each animal was thus its own control. Single doses of 15, 25 and 40 Gy 60Co were used. The follow-up time was 11 to 22 weeks after irradiation. A histochemical method, recording diaphorase (NADH2 and NADPH2) activity in osteocytes, was employed. This method is regarded as superior to conventional histology. No evidence of osteocyte death was found even after 22 weeks following 40 Gy irradiation. This is interpreted as an indication that the osteocytes, which are end stage cells, are relatively radioresistant.

Animals↗
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↗
PubMed1985

Dose-response for bone regeneration after single doses of 60Co irradiation.

The Bone Growth Chamber (BGC) methodology was used to establish a dose-response relationship for regeneration of mature bone tissue after irradiation of 5, 8, 11, 15 and 25 Gy single dose 60Co. The BGC, which is a titanium implant, was inserted in the proximal tibial metaphyses, bilaterally, of a rabbit immediately following local irradiation to one tibia. Each animal thus served as its own control. During a healing period of 4 weeks, the two canals penetrating the implant became filled with more or less newly formed bone. At the end of the healing period, the implants were removed and taken apart and the newly formed bone was collected and its volume measured by microradiography and microdensitometry. It was found that in the dose range of 5 to 8 Gy bone regeneration was reduced by about 20% as compared to non-irradiated controls. Between 8 and 11 Gy, there was a critical range in that a small increase in dose resulted in a greatly reduced bone formation. At 11 Gy and above, the depression in bone formation, as compared to non-irradiated controls, was about 65 to 75%.

Animals↗
PubMed1985

Alterations in bone regenerative capacity after low level gamma irradiation. A quantitative study.

In the present study the influence of single 2.5 and 5 Gy doses of irradiation on the regenerative capacity of mature bone tissue has been investigated. To the knowledge of the present authors, no quantitative analysis of bone repair after low doses of irradiation has been presented previously. The experimental model used was the Bone Growth Chamber (BGC), which is a porous implant made of titanium. Each one of twenty animals was irradiated with 2.5 or 5 Gy to one tibial metaphysis. Directly after irradiation each animal had BGC:s inserted bilaterally into the tibial metaphyses. Thus, each animal served as its own control. Four weeks after irradiation the BGC:s were removed and the newly formed bone was collected from the implant pores and was analyzed by microradiography and quantified by microdensitometry and histology. It was found that 2.5 Gy irradiation led to no statistically significant alteration in bone formation as compared to non-irradiated controls. At the 5 Gy dose level, however, there was a significant reduction of bone formation as compared to non-irradiated controls.

Animals↗
PubMed1980

Irradiation injury of bone tissue. A vital microscopic method.

A vital microscopic method using the titanium chamber for observation of bone irradiation injury in situ is described. The subsequent development of bone tissue resorption and replacement with a pathologic immature bone could be observed and recorded.

Animals↗
PubMedDate not supplied

Integration of titanium implants in irradiated bone. Histologic and clinical study.

Nine patients who had undergone combined surgical and radiologic treatment for malignant tumors had skin-penetrating titanium implants inserted in the bone tissue in the treated region at various time intervals after irradiation. The absorbed dose to the implant region varied between 25 and 86 Gy normalized to five fractions of 2.0 Gy/wk, according to the cumulative radiation effect formula. The time interval between irradiation and fixture insertion varied from 9 months to 37 years. Of the 35 fixtures installed, only five were lost because of lack of osseointegration. The follow-up time from implant insertion ranged from 15 to 44 months.

Ear Neoplasms↗
PubMedDate not supplied

Juvenile nasopharyngeal angiofibroma. A report of eighteen cases.

Juvenile nasopharyngeal angiofibroma is a disease afflicting mainly adolescent males. The lesion is benign but characterized by local aggressive growth. In advanced cases the tumour may extend intracranially. In this study 18 cases of juvenile nasopharyngeal angiofibroma were investigated. Tumour extension was assessed with the use of angiograms and CT and the individual cases staged in four different categories on the basis of tumour extension. Two cases were staged as I (tumour confined to the nasopharynx), 7 cases as II (tumour extending into nasal cavity and/or sphenoid sinus), 8 as III (tumour extending into one or more of the following: antrum, ethmoid sinus, pterygomaxillary and infratemporal fossae, orbit and/or cheek) and one as IV (tumour extending into the cranial cavity). Preoperative arterial embolization was performed in 8 cases. All patients underwent surgery; none received irradiation. The follow-up period was 6 yrs 4 mo (6 months-17 years). In one case of intracranial extension, tumour recurrence occurred. It is concluded that with the aid of CT and arteriograms to evaluate the extension of the tumour and preoperative embolization, this lesion can be cured in the vast majority of cases, with surgery as the method of choice.

Adolescent↗
PubMedDate not supplied

A comparative study of enzyme histochemical features in the gerbilline and human cholesteatoma.

Spontaneous and experimentally induced cholesteatoma in the Mongolian gerbil has been found to exhibit histopathological similarities to human aural cholesteatoma and has been suggested as an experimental model for studies of the clinical situation. In an attempt to further characterize this model, we compared experimentally induced cholesteatomas in the external auditory canal from gerbils with those of the human ear by means of a correlated histopathologic and enzyme histochemical study. The human and gerbilline cholesteatomas revealed similar histopathologic features. Even enzyme histochemically, the human and experimentally induced cholesteatomas demonstrated similar features. Thus glucose-6-phosphate dehydrogenase activity, an indicator of oxidative metabolism, was demonstrated especially in the stratum granulosum cells of the heavily orthokeratinizing squamous epithelium adjacent to the cholesteatomas. The human ear canal skin also revealed enzyme histochemical characteristics similar to the squamous epithelium lining the human cholesteatoma. The hydrolytic enzyme activity (leucyl-aminopeptidase) was strong in the connective tissue surrounding human cholesteatoma when compared with that of ear canal skin. In the gerbilline cholesteatoma, this activity was demonstrated especially in the connective tissue adjacent to eroded bone, which possibly may facilitate cholesteatoma progression. We conclude that experimentally induced cholesteatoma has both histophatological and enzyme histochemical similarities to human aural cholesteatoma and therefore it is suggested that the gerbilline model may be used for studies on the development of human cholesteatoma. Our results support the view that cholesteatoma may originate from migrated hyperkeratinizing cells from the epidermis of the tympanic membrane or the meatus.

Acid Phosphatase↗
PubMedDate not supplied

Dynamics of irradiation injury to bone tissue. A vital microscopic investigation.

The dynamic changes after a single dose of 15, 25 or 40 Gy 60Co were followed in a titanium vital microscopic bone chamber which permitted observation of the same tissue compartment for over 2 years. The chamber consists of a hollow screw containing 2 glass rods 100 micron apart. The device was inserted into the cortex of the proximal tibial metaphysis of a rabbit. During a healing period of 4 to 6 weeks the space between the glass rods became filled with bone and vessels and in some cases fat. Once a steady state in bone remodelling had been achieved, the animals were irradiated. Vital microscopy was then performed at regular intervals. Mature bone was relatively radioresistant since remodelling continued at a normal rate. In contrast, immature woven bone remained unlamellarized and in some animals tended to increase in amount. The vascular architecture was largely unaltered, even after 40 Gy. Thrombosis or hemorrhage clearly attributable to irradiation was not noted. Initially, the number of fat cells was reduced but repopulation was later seen in several cases.

Adipose Tissue↗
PubMedDate not supplied

Provoked repetitive healing of mature bone tissue following irradiation. A quantitative investigation.

A titanium implant, the bone harvest chamber (BHC), was used to investigate the regenerative capacity of mature bone after irradiation. One BHC was inserted in each proximal tibial metaphysis of a rabbit. One of these implant sites was irradiated (60Co single dose) to either 15 or 25 Gy while the other served as control. Newly formed bone grew through a canal that penetrated the implant. This newly formed bone was harvested from the implant every three weeks following irradiation and then quantified by microradiography and computer-assisted densitometry. In this way a ratio between bone formed on the irradiated side in comparison with the control could be established. An immediate depression in bone formation compared with the non-irradiated controls, was seen at both dose levels. A recovery in bone regenerative capacity was seen at 15 weeks after 15 Gy while the decrease in bone formation remained constant after 25 Gy during the 30 week follow-up period.

Animals↗
PubMedDate not supplied

Bone healing following irradiation during tourniquet ischaemia.

The bone harvest chamber (BHC) methodology, a titanium implant for quantitative evaluations of bone healing, was used in order to investigate the radioprotective function of anoxia, in healing bone tissue. After incorporation of one BHC in each proximal tibial metaphysis of a rabbit it was possible to collect newly formed bone specimens in 3-week-periods without animal sacrifice. The amount of bone was determined by microradiography and densitometry. Ten animals divided into 2 groups were used. One group receiving a single dose of 25 Gy during tourniquet ischaemia was compared with another receiving the same dose during normal blood perfusion. A significantly improved bone healing response was seen in the ischaemic group, with a tendency to further improvement with increasing time after irradiation.

Animals↗
PubMedDate not supplied

A histomorphometric study of bone reactions to titanium implants in irradiated bone and the effect of hyperbaric oxygen treatment.

The present study was undertaken to histomorphometrically analyze early peri-implant bone tissue reactions that occur after radiotherapy and to determine whether hyperbaric oxygen therapy (HBO) affects bone tissue at the microscopic level by altering bone morphology. Twelve rabbits received a single dose (15 Gy) of cobalt60 radiation to one hind leg and the other hind leg served as a control. Titanium screws were placed into the femur and tibia directly after irradiation. Six animals received HBO during the first 4 postoperative weeks. After 8 weeks of follow-up, bone specimens containing the screws were prepared for histomorphometry. Bone-metal contact and the amount of bone in the thread areas and in the mirror areas were measured in a blinded manner. Periosteal bone formation and bone remodeling decreased after irradiation; also after HBO treatment. Hyperbaric oxygen therapy improved bone formation in nonirradiated bone and to some extent also in the irradiated bone. Bone maturation was improved in the HBO animals after irradiation. It was concluded that irradiation reduces the capacity for osseointegration of titanium implants. Hyperbaric oxygen treatment may improve bone formation and especially has positive effects on bone maturation after irradiation.

Animals↗