The mortality in an age cohort followed from birth to age 70.

The Study of Men Born in 1913 is a prospective population study of cardiovascular diseases in Gothenburg, Sweden, that started in 1963. To describe survival curves and mortality pattern, all boy-children born alive in 1913 in the city of Gothenburg, were identified. This birth cohort was followed from birth to age 70 for residence, vital status and cause of death. At the age of 50 years, 25% of the birth cohort were dead and at age 70, 43% had died. The high infant mortality and the great impact of infectious diseases in the beginning of this century is illustrated. The death rate for the cohort was almost identical to national figures for men in the same age group. Men who migrated from Gothenburg had a death rate very similar to those who stayed. It can therefore be concluded that the men in the Study of Men Born in 1913 is a representative sample not only of men in Gothenburg but also of men in Sweden as far as mortality is concerned. Special attention was paid to death from otitis media complications, congestive heart failure, and diabetes. Few persons died from these diseases before age 50 when the prospective study started and therefore did not influence the study of the natural history for these conditions to any great extent. Otitis media infections might be studied retrospectively from this age.

New mobilization and laterofixation procedure for cricoarytenoid joint ankylosis in rheumatoid arthritis.

Ankylosis of the cricoarytenoid joints due to rheumatoid arthritis can cause severe laryngeal obstruction. With a mobilization and laterofixation procedure, five of six patients were successfully operated upon. Documented improvement of breathing was achieved and the voice function was acceptable after decannulation.

A simple operation for bilateral vocal cord paralysis.

To reduce the laryngeal obstruction in bilateral vocal cord paralysis, a new method of laterofixation was developed. The method is technically simple and less traumatic than previously published methods. No peroperative tracheostomy is needed. During surgery two needles are inserted through the thyroid cartilage. A nylon thread is passed through the needles and the needles are then withdrawn. The thread thus forms a permanent loop around the vocal cord. The effects of the laterofixation on breathing and on the voice are documented by assessment of upper airway resistance and by two listening panels respectively. Thirteen patients have been operated upon so far. In most cases the breathing was improved and the influence on the voice was moderate and adjustable. If needed the possibility to perform a more extensive surgical procedure still remains. We suggest our method of laterofixation to be the first treatment of choice in patients suffering from bilateral vocal cord paralysis.

Middle ear disease in samples from the general population. Prevalence and incidence of otitis media and its sequelae. The study of men born in 1913-23.

A study of 1371 men 20, 30, 50 and 60 years old and living in Göteborg was performed to obtain information on the incidence and prevalence of otitis media in a non-selected population. In addition to anamnestical data, a thorough examination of the ENT-status was made by one observer. There was no indication that otitis media has become a more rare disease since the early part of the century. However, the course of the disease does seem to be shorter and milder in more recent decades. This conclusion is supported by a substantially higher frequency of grave pathologic changes in the tympanic membranes in the two oldest cohorts compared with the two younger. A further indication is that mastoidectomies have become a rare type of operation during recent decades.

Five-year experience with skin-penetrating bone-anchored implants in the temporal bone.

A method for stable integration of titanium-implants in bone tissue has been developed at the University of Gothenburg, Sweden. Screw shaped implants have been inserted in the temporal bone using a delicate surgical technique. After healing-in of the implants it is, in a later séance, possible to penetrate the skin to establish a reaction-free percutaneous passage. An up to 5-year clinical follow-up has shown the possibilities of this new method in the treatment of patients with e.g. certain hearing disorders or facial defects after tumour surgery.

Direct bone anchorage of external hearing aids.

Some patients with hearing disorders cannot wear a conventional hearing aid but have to use bone conduction in which the aid has to be attached with steel springs over the head. A new method of reconstruction involving the insertion of bone-anchored screws has been tested in a clinical survey of 14 patients. A titanium implant was anchored in the temporal bone and, in a later session, connected to a skin penetrating abutment. An external hearing aid was snapped on to the abutment. The patients have now been followed up for 53 months. There have been no problems with the bone anchorage or with infections around the skin penetration site. The hearing of the patients has improved. The cosmetic result is reported to be favourable.

Osseointegrated titanium implants in the temporal bone. A clinical study on bone-anchored hearing aids.

The purpose of this study is to investigate the possibilities for attaching a new type of direct bone conduction hearing aid. Using a gentle surgical technique, titanium screws were inserted into the temporal bone of fourteen patients suffering from hearing impairment. The implants became integrated with the living bone tissue and have remained so for a follow-up period of, at present, two to four years. It is therefore concluded that titanium implants may be osseointegrated in the temporal bone in a similar manner to that previously described for long bones. The bone-anchored titanium screws were connected to a permanently skin-penetrating abutment, which in turn was used for attachment to a hearing aid. In this way a direct bone conduction without obstructing soft tissue layers is secured. The permanent skin penetration caused no adverse soft tissue effects. The new system has improved pure-tone hearing threshold by about 15 dB. Further research is aimed at the construction of a new hearing aid that is better adapted to the impedance situation existing in the directly bone-anchored cases.

Analysis of the mechanical impedance of bone-anchored hearing aids.

Some patients who need hearing aids are unable to use an apparatus which transmits the sound via the external ear canal and have to use a bone conduction hearing aid. The bone vibration transducer of this aid is applied to the skin over the mastoid process and the sound is transmitted via the soft tissue and bone to the cochlea. The pressure needed to apply the transducer often gives the patient discomfort and the damping effect of the soft tissue gives poor quality of the sound transmitted. Advances in the ability to permanently implant foreign material in the body and perform permanent skin penetration has made it possible to develop a bone-anchored hearing aid. Fourteen patients have been equipped with such hearing aids. To be able to give these patients the best hearing aid, a new transducer has to be constructed to match the new situation. The impedance of the bone-anchored titaniumscrew/skull has been studied and the resistance and reactance of the mechanical impedance have been measured. The influence of a damping soft tissue layer over the bone has been analyzed. The difference between the impedance of the skull and the impedance of the soft tissue + skull was in the order of 10 to 25 dB depending on the frequency.

Peroperative drill-generated noise levels in ear surgery.

A simple technique for the measuring of sound intensities produced by drilling in ear surgery is presented. In 6 patients the sound level from drilling in the mastoid exceeded 100 dBA. The drilling device should be so designed as to avoid acoustic trauma. Furthermore, a surgical technique should be selected, which minimizes the noise levels and duration of exposure as far as is possible.

A clinical pilot study on preformed autologous ossicles. II.

A research project concerning performed autologous ossicles has been going on for more than ten years. Animal experimental studies were followed by a clinical pilot study which showed that bone could be produced in a titanium mould placed in the proximal tibia metaphysis. In the present investigation, in which another five patients were operated on, the experimental design was changed compared to the first pilot study and bone production was improved. In addition to the tibial moulds ten titanium cylinders were placed around a bony bridge prepared in the linea temporalis of the ear to be reconstructed. Nine out of ten of these cylinders contained bone suitable for ossiculoplasty. Histology showed higher osteocyte density and a higher proportion of vital looking osteocytes in the performed grafts compared with a peroperatively sculptured graft of cortical bone. On histochemical investigation the performed graft cells seemed viable at the time of transplantation. The technique for obtaining a preformed autologous ossicle through the titanium cylinders in the temporal bone was easy to perform and the patients did not experience any discomfort. The risk of infection in this area was judged to be small.

A clinical pilot study on preformed autologous ossicles. I.

The study is part of a project aimed at obtaining an autologous, preformed transplant for reconstruction of a defect ossicular chain. In animal experiments we found that bone could be produced in a titanium mould placed in the tibia of the rabbit and dog. To find out whether this observation was applicable in man, 5 patients with ossicular defects were selected. A titanium mould containing two chambers was placed in the proximal tibial metaphysis for 6 months. When the moulds were extracted bone was found in 7 of the 10 chambers. In 2 of these the bone was stable and suitable for ossiculoplasty. On histological examination the same picture as in the animal experiments was found, an outer layer of cortical bone surrounding a system of spongy bone with marrow and haematopoietic cells. Microradiological examination verified the presence of mineralized bone tissue.