Implant survival rate in bone-anchored hearing aid users: long-term results.

OBJECTIVE: To investigate the long-term survival rate of bone-anchored hearing aid implants, and to assess the number of patients who stop using their bone-anchored hearing aid. METHOD: Patients who underwent bone-anchored hearing aid surgery between September 1977 and December 1986 were identified from a prospective database. Data were collected from patient records. RESULTS: During the study period, 143 patients were fitted with a bone-anchored hearing aid. Records from 132 patients were found, with a mean follow up of nine years. A total of 150 implants were installed in these patients. A total of 41 implants (27 per cent) were lost during follow up: 17 lost osseointegration, 16 were removed and eight were lost due to direct trauma. At the end of follow up, 119/132 (90 per cent) patients were still using their bone-anchored hearing aid. CONCLUSION: Despite a high incidence of implant loss over time, a large number of patients still continued to use their bone-anchored hearing aid.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Long-term results with the titanium bone-anchored hearing aid: the U.S. experience.

OBJECTIVE: The purpose of this study is to evaluate the long-term safety and efficacy of the titanium bone-anchored hearing aid (BAHA). STUDY DESIGN: A retrospective review of 24 patients implanted with the BAHA between 1984 and 1987 in a multiinstitutional study designed to evaluate the device in the United States was performed, including detailed clinical and audiologic evaluations of the 10 patients implanted at the Columbia-Presbyterian Medical Center in New York. The data were collected from patients' charts, questionnaires, and the Nobel Biocare patient contact and repair records. PATIENTS: Candidates for the BAHA are unable to use a conventional air conduction hearing aid because of congenital aural atresia, draining mastoid cavities, or recurrent otitis externa. The audiologic indications are a conductive or a mixed hearing loss with a bone conduction average of 45 db or better and a speech discrimination score of 60% or better. INTERVENTION: A BAHA was implanted in a two-stage procedure under local anesthesia on an outpatient basis. MAIN OUTCOME MEASURES: Patients' satisfaction with the device, hearing improvement, and complication rates were reviewed. RESULTS: The majority of the patients analyzed (78%) are still using the device an average of 15.6 hours/day 10 to 13 years after implantation. The overall satisfaction score was 4.5 (1, worst; 5, best). In sound field testing, the mean speech reception threshold improved from 52 db to 27 db (p < 0.05). There were no major complications. CONCLUSION: The BAHA is a safe and effective bone conduction hearing aid with wide applications for patients with bone conduction hearing levels of 45 db and discrimination scores of 60% or better.

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.

Effects of irradiation on osseointegration before and after implant placement: a report of three cases.

Three patients irradiated as a part of cancer treatment, both before and after placement of endosseous implants, were studied. Total irradiation doses varied from 80 to 195 Gy in the tumor/implant area. Implants failed at a rate of 64.2% during a 3-year follow-up period. All patients developed osteoradionecrosis in the tumor cavities adjacent to the implants. The combined effects of the pre- and postoperative irradiation, in conjunction with the placement of implants, appear to challenge the limits of osseointegration. Until further knowledge is obtained regarding how such highly radiated tissue should be handled, it is recommended that if anchorage of craniofacial prostheses is attempted according to osseointegration principles, it should be performed with the utmost care.

Magnetic resonance imaging in patients with dental implants: a clinical report.

Magnetic resonance imaging is used more and more frequently as a diagnostic tool. Because high magnetic fields are used, knowledge on how these will affect implanted material and the patient is of great importance. Ferromagnetic properties of implant materials are seldom described by the manufacturer, but a doctor requesting magnetic resonance imaging of a patient must know about these properties. Not only is the composition of an alloy important, but also the size and shape of the metallic material as well as its position in the body. Implants from the Brånemark System were tested; findings indicated that the implants were not influenced when exposed to magnetic resonance imaging. The artifacts caused by the implants were minor and did not jeopardize the evaluation of the scans. However, magnet keepers attached to the implants were found to cause major artifacts and must be removed before an implant patient is referred for a magnetic resonance imaging examination.

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.