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Biomedical subjects

A Tjellström

Publications and source records attributed to A Tjellström.

At least 19 recordsLinked to original sources
PubMed2006

Survival rate of self-tapping implants for bone-anchored hearing aids.

OBJECTIVE: The purpose of this study was to investigate whether a new self-tapping implant for a bone-anchored hearing aid (BAHA) had the same high frequency of osseointegration as previous implants requiring pre-tapping. METHOD: Over a three-year period, 144 consecutive implants were placed in the mastoid for BAHA and evaluated. RESULTS: Two implants were lost; both were of the self-tapping type. One was in an 11-year-old boy, who lost his implant six weeks after surgery when the BAHA was fitted. The other was in an elderly man, a heavy smoker with diabetes. Using Fisher's exact test, there was no significant difference between the two groups (p>0.30). CONCLUSION: Self-tapping implants facilitate surgery and shorten operating time. Over a short follow up, we did not find any significant difference; however, it is important to follow these implants over a longer time period.

Adolescent↗
PubMed2001

Bone-anchored hearing aids: current status in adults and children.

The BAHA is the only cochlea stimulator in clinical use using bone conduction as the mode of stimulation. Sound transmitted through bone conduction is a natural way of hearing and the fundamentals of bone conduction are presented. The simple but important procedure has been refined and is presented in some detail. As the BAHA is approved by the Food and Drug Administration for children, aspects relevant for this age group will be addressed. The future includes semi-implantable BAHA, percutaneous electrical coupling, and a BAHA for tinnitus suppression.

Adult↗
PubMed2001

Osseointegrated implants in children: experience from our first 100 patients.

This study was undertaken on 100 children aged 16 years or under intended for installation of osseointegrated implants. Of these, 76 had implants installed for bone-anchored hearing aids or prostheses. The main indication for implant installation was a bilateral ear malformation. Surgery was generally performed as a two-stage procedure with a healing time of 3 to 4 months in between. Available bone thickness was on average 2.5 mm, and lack of bone necessitated bone augmentation in 12 patients. Thirty-nine percent of implants were installed in contact with the dura, sigmoid sinus, or an air cell. Implant failures were 5.8% of 170 inserted fixtures. Adverse skin reactions appeared in 9.1% of patients over a 21-year follow-up period. Revision surgery was undertaken in 22% of patients because of appositional growth of the temporal bone. Of the 24 children considered but not found suitable for osseointegration surgery, plastic surgery was considered a better option, or growth of the temporal bone was awaited. It is concluded that the rate of implant failure is lower in children; the frequency of skin reactions is the same as in adults, but revision surgery is more common in young patients because of new bone formation. Our clinical experience supported by the data presented in this article suggests that the concept could be used with good functional and aesthetic results in children.

Adolescent↗
PubMed2000

Evaluation of implant losses and skin reactions around extraoral bone-anchored implants: A 0- to 8-year follow-up.

This is an 8-year follow-up of a group of 214 patients who underwent surgical insertion of titanium implants in the mastoid process for the retention of bone-anchored hearing aids and auricular prostheses. The skin reactions around the implants and the various factors dealing with implant loss were evaluated. The number of patients who never had any episode of adverse skin reactions during the 8-year period is 70% and is about the same as previously reported. The frequency and degree of adverse skin reactions were noted to be decreasing with time. The young age group had the highest incidence of adverse skin reactions, and this high frequency is consistent with results of earlier reports. None of the remaining group of patients (30%) who had 1 or more episodes of adverse skin reactions lost their implants because of this problem; most implant losses were primarily the result of loss of integration. The probability of losing an implant because of adverse skin reactions is quite low; however, these skin reactions, if left untreated, may eventually lead to implant loss or withdrawal.

Adolescent↗
PubMed2000

Histologic evaluation of retrieved craniofacial implants.

A retrieval study was performed on implants placed extraorally in the craniofacial region. The study included 19 implants retrieved from 16 patients. The implants were all stable at the time of removal. For various reasons, 5 of the implants were never loaded, whereas 14 of the implants had a known loading period of 3 months to 7 years 7 months. The reasons for removal varied but included the following: death in 1 case; poor results of the bone-anchored hearing aid in 7 cases; host-related reasons, varying from soft tissue irritation to infection or pain, in 6 cases; change of treatment plan in 1 case; and scheduled direct removal at the time of insertion in 1 case. The results of the histologic evaluation were similar to those reported in retrieval studies of a corresponding design used intraorally.

Adolescent↗
PubMed2000

Vibration characteristics of bone conducted sound in vitro.

A dry skull added with damping material was used to investigate the vibratory pattern of bone conducted sound. Three orthogonal vibration responses of the cochleae were measured, by means of miniature accelerometers, in the frequency range 0.1-10 kHz. The exciter was attached to the temporal, parietal, and frontal bones, one at the time. In the transmission response to the ipsilateral cochlea, a profound low frequency antiresonance (attenuation) was found, verified psycho-acoustically, and shown to yield a distinct lateralization effect. It was also shown that, for the ipsilateral side, the direction of excitation coincides with that of maximum response. At the contralateral cochlea, no such dominating response direction was found for frequencies above the first skull resonance. An overall higher response level was achieved, for the total energy transmission in general and specifically for the direction of excitation, at the ipsilateral cochlea when the transducer was attached to the excitation point closest to the cochlea. The transranial attenuation was found to be frequency dependent, with values from -5 to 10 dB for the energy transmission and -30 to 40 dB for measurements in a single direction, with a tendency toward higher attenuation at the higher frequencies.

Acoustic Stimulation↗
PubMed2000

Facial nerve paralysis following repair of the external ear canal with ionomeric cement.

A 20-year-old man developed a complete facial nerve paralysis following surgical reconstruction of the posterior ear canal with ionomeric cement. The paralysis developed gradually during the second and third postoperative weeks. Six weeks following the complete removal of the cement, the facial nerve recovered completely. The literature contains reports of diffusion of aluminum ions, which can reach toxic levels in tissue fluid and adjacent bone as the cement hardens. This side effect has been reported to cause an inflammatory response in the dura and brain and has led to fatalities. To our knowledge, there has been no other report of an ionomeric cement having a direct toxic effect on peripheral nerve transmission. Because ionomeric cements are used routinely in otosurgery, especially in canal reconstructions where the proximity to the facial nerve is evident, it is important to use caution when introducing ionomeric cements into near-nerve anatomic locations.

Adult↗
PubMed1999

Long-term study of quality and safety of osseointegration for the retention of auricular prostheses.

The aim of this article is to describe the safety and quality of the osseointegrated implant technique for the retention of craniofacial prostheses, to present a protocol for collection of clinical data, and to discuss the impact of the procedure on the patient quality of life. A protocol was designed and used to study patients who had received auricular prostheses consecutively since 1979 at our department. The patients were asked to answer a questionnaire designed to describe symptoms and problems specific for someone wearing an auricular prosthesis. In total, 99 patients received 107 prosthetic ears (8 patients had bilateral defects) retained on 309 implants (2 to 4 implants/ear). Patients of all ages were represented, and only 9 discontinuities were reported. Most patients (95%) wear their prosthesis every day, in most cases more than 10 hours/day. The follow-up period ranged from 1 to 12 years, giving a total of 2624 postoperative observations of implants, with a 3% incidence of significant skin reaction. We conclude that the surgical technique for auricular prostheses retained on osseointegrated implants is simple and associated with a low rate of peroperative and long-term complications. It offers a high degree of stability and aesthetic satisfaction.

Adolescent↗
PubMed1999

Osseointegrated implants in irradiated bone: a case-controlled study using adjunctive hyperbaric oxygen therapy.

PURPOSE: The current investigation was undertaken to study whether osseointegration of implants in irradiated tissues is subject to a higher failure rate than in nonirradiated tissues. It further aimed to study whether hyperbaric oxygen treatment (HBO) can be used to reduce implant failure. PATIENTS AND METHODS: Seventy-eight cancer patients who were rehabilitated using osseointegrated implants between 1981 and 1997 were investigated. Three groups of patients were compared: irradiated (A), nonirradiated (B), and irradiated and HBO-treated (C). In addition, 10 irradiated patients who had lost most of their implants received new ones after HBO treatment. These were compared as a case-control group. RESULTS: Implant failures were highest in group A (53.7%). Implant failure was 13.5% in group B and 8.1% in group C. The difference between group A and the other two groups was statistically significant (P = .001 to .0023, Mantell's test). HBO significantly improved implant survival in the case-control group from 34 of 43 implants lost to 5 of 42 lost (P = .0078). CONCLUSIONS: Implant insertion in irradiated bone is associated with a higher failure rate. Adjuvant HBO treatment can reduce the failures.

Adult↗
PubMed1999

Guided tissue generation in the temporal bone.

Ten patients with malformations of the temporal bones were submitted to installation of implants for anchorage of bone-anchored auricular epistheses or bone-anchored hearing aids. Due to lack of bone in the temporal region, expanded polytetrafluoroethylene membranes were used to aid bone generation, each patient serving as his or her own control. It was found that bone formation around the flange fixtures covered with membranes increased significantly compared to the uncovered fixtures. It is concluded that the use of barrier membranes is one way to support bone generation in temporal bones lacking sufficient bone for implant-related surgery.

Bone Regeneration↗
PubMed1998

Stability measurements of craniofacial implants by means of resonance frequency analysis. A clinical pilot study.

Nineteen patients previously treated with 52 implants for anchorage of craniofacial prostheses were subjected to implant stability measurements by means of resonance frequency analysis (RFA), six months to 15 years after implant placement. The resonance frequency (RF) of a transducer attached to the implant abutment was measured by using a frequency response analyser, a personal computer (PC) and dedicated software. Statistically significant higher RF values were seen for implants in the temporal bone as compared to implants in the nose and periorbital regions. There was a positive correlation with time since implant placement for the period from six months up to seven years. It was concluded that the preliminary results suggest that implant stability increases with time and that implants in temporal bone are more stable than implants in the bone in the nose and periorbital regions, probably reflecting differences in bone density.

Adult↗
PubMed1998

Reconstructing the human face by using the tissue-integrated prosthesis.

Reconstructing the human face with autogenous tissue is extremely difficult. A prosthetic device is often used, but retention is a problem. The tissue-integrated prosthesis has resolved this issue, however, and the technique is currently available worldwide. The tissue-integrated prosthesis--that is, a prosthesis supported (retained) by osseointegrated implants in the underlying bone--originated during the 1950s, when Brånemark began his laboratory studies of tissue healing in Sweden. The term "osseointegration" was introduced in 1977 and later was defined as "direct anchorage of an implant by the formation of bony tissue around the implant without the growth of fibrous tissue at the bone-implant interface." Early studies during the 1980s and 1990s documented the success of reconstruction of the human face with use of the tissue-integrated prosthesis. Herein we describe three cases in which this reconstructive procedure was successful.

Ear, External↗
PubMed1997

Acute human trial of the floating mass transducer.

Five patients underwent acute implantation of the Floating Mass Transducer (FMT) to evaluate the ability of the FMT to produce measurable auditory thresholds when temporarily placed in the middle ears of patients undergoing routine stapedotomy procedures. The FMT was placed on the long process of the incus in an inferior position, as is planned for clinical application, and in two additional positions. The ability of the FMT to produce measurable auditory thresholds was demonstrated in all patients. Results were affected by the lack of a healing period, the presence of a fixed stapes and an open middle ear space, and patient sedation.

Audiometry↗
PubMed1997

The bone-anchored hearing aid (BAHA) in children with auricular malformations.

A retrospective study was undertaken to evaluate the outcome of the use of the bone-anchored hearing aid (BAHA) in children. All patients included in the study had bilateral auricular malformations. Previous alternatives had been conventional hearing aids or surgical middle ear reconstruction. Thirty-seven patients under 16 years of age were studied. The most common syndrome in the group was Treacher Collins. Sixteen of the patients had earlier middle ear reconstruction, the results of which did not produce social hearing. Of 40 inserted fixtures to anchor the BAHA, three were lost during the follow-up period because of failed osseointegration. Skin reactions were graded according to a clinical scoring system and were determined to be comparable in number and severity to those of an adult population. All patients in the study considered the BAHA to be superior to earlier bone-conduction devices. It is concluded that the BAHA is an excellent alternative to bone-conduction devices in children with auricular malformations. Middle ear surgery can be postponed until adulthood or abandoned, especially in syndromic patients in whom it is known to be difficult and unpredictable.

Adolescent↗
PubMed1996

Titanium-anchored prostheses in otology.

In the late 1970s, Per-Ingvar Branemark and coworkers in Goteberg, Sweden, successfully introduced osseointegrated titanium implants into clinical practice. They had achieved the previously elusive goal of producing stable, secure percutaneous implants anchored in underlying cortical bone. Two applications of these implants to otology were obvious: (1) to provide a coupling for bone-conduction hearing aids and (2) to provide fixation points for anchoring of auricular prostheses. Before describing the current state of these clinical applications and considering future potential uses, the authors review the basis for titanium osseointegration.

Bone Conduction↗
PubMed1995

Immunohistochemical study of the soft tissue around long-term skin-penetrating titanium implants.

Bone-anchored percutaneous titanium implants have become a well-established clinical procedure with a low incidence of adverse reactions. However, passage through the skin leads to a breach in the barrier to exogenous pathogens. In the present study, monoclonal antibodies were used to investigate the distribution of lymphocyte subpopulations in the soft tissue around such implants. Eight biopsies from patients with clinically irritated skin, five from non-irritated and eight from skin without skin-penetrating implants were analysed. The number of immune cells was increased in the group of patients with skin penetration compared with patients without skin penetration. In the group with clinical irritation there was an increased level of B-lymphocytes compared with those without irritation. The data suggest that there is an immunological compensation for the mechanical loss in barrier function at these implants and that an antibody-mediated response is present at clinical signs of irritation.

Adolescent↗