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.

Craniofacial osseointegration.

In year 2007, 30 years have elapsed since the first patient was supplied with a craniofacial osseointegrated implant. The reason for implanting in this patient was a severe conductive hearing loss, which necessitated the use of a bone conduction hearing aid. By utilizing the possibility to transmit sound to the cochlea via direct bone conduction, a new era in audiology was established. Further applications of osseointegration in the craniofacial field is related to the rehabilitation of patients with defects from cancer therapy, malformations, traumatic amputations and burns. Specific fields of osseointegration in this respect are due to possible side effects from radiotherapy and chemotherapy that will affect osseointegration negatively. Other aspects are related to osseointegration in children. This review will focus on the knowledge gained during the first 30 years of craniofacial osseointegration.

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.

Recovery from orbital floor fractures: a prospective study of patients' and doctors' experiences.

This study aimed at investigating the extent to which remaining symptoms and signs troubled patients in the year after suffering from zygomatico-orbital fractures, and whether there was any discrepancy between patients' and doctors' opinions as to the presence of symptoms and signs. Over the course of 1 year, 46 patients were included. Symptoms and clinical findings were registered in a 'doctor's protocol', and patients described self-reported symptoms and signs using a visual analogue scales (VAS) in a questionnaire administered 5 times during the year after injury. The VAS proved to be a useful instrument for evaluating patient discomfort and indicating differences between patients' and doctors' opinions regarding the presence of symptoms and signs. Agreement between the two was good regarding the presence of objective and measurable signs, such as facial asymmetry and diplopia. When it came to sensibility and mouth-opening ability, however, discrepancies were evident. It is desirable that reliable methods for measuring sensibility and evaluating mouth opening are included in follow-up routines. This would increase our knowledge of the course of healing, prognosis and possibilities for the prevention and active treatment of these problems.

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.

Frequency of antibiotic-associated diarrhoea in 2462 antibiotic-treated hospitalized patients: a prospective study.

The frequency of antibiotic-associated diarrhoea (AAD) and Clostridium difficile-associated diarrhoea (CdAD) was prospectively determined in a population of 2462 patients recruited from five Swedish hospitals, including divisions for infectious diseases, orthopaedics, surgery, geriatrics, nephrology and internal medicine. AAD developed in 4.9% of the treated patients. Faecal samples were obtained from 69% of patients with AAD and 55.4% were positive for C. difficile cytotoxin B. The frequency of AAD varied from 1.8 to 6.9% at the participating centres (P < 0.001). The frequency of AAD also varied considerably between medical disciplines and wards within different hospitals and was highest in the nephrology and geriatric units (6.7 and 7.1%, respectively). There was no difference in frequency of AAD when analysed with respect to gender or age. Medical interventions (laxative treatment, endoscopy and abdominal surgery) or presence of one concomitant disease (diabetes, malignancy, chronic renal disease and inflammatory bowel disease) did not significantly affect the frequency of AAD, whereas patients suffering from two or more of these illnesses had significantly (P = 0.001) higher frequencies of AAD. Patients treated with antibiotics for 3 days had a significantly (P = 0.009) lower frequency of AAD than those treated for longer periods. Treatment with cephalosporins, clindamycin or broad-spectrum penicillins was associated with an increased risk of AAD. With specimens from one centre, 62.5% of tested patients with AAD and 33.8% of asymptomatic patients were positive for cytotoxin B. Although C. difficile cytotoxin B in stool samples was significantly associated with AAD (P = 0.003), the causal relationship with diarrhoea is not always evident.

A bone-anchored hearing aid for patients with pure sensorineural hearing impairment: a pilot study.

This pilot study assesses the potential benefits of an optimized bone-anchored hearing aid (BAHA) for patients with a mild to moderate pure sensorineural high frequency hearing impairment. The evaluation was conducted with eight first-time hearing aid users by means of psycho-acoustic sound field measurements and a questionnaire on subjective experience; all of the patients benefited from the BAHA. On average, the eight patients showed improvement in PTA threshold of 3.4 dB and in speech intelligibility in noise of 14%. Seven of the subjects, also fitted with present standard air conduction hearing aids (ACHA) found the ACHA thresholds to be improved more than the BAHA ones. In speech tests, the ACHA was only slightly better; these patients chose between their different hearing aids according to the sound environment. Although the BAHA was preferred for wearing and sound comfort, it cannot be used as the sole aid for patients with pure sensorineural impairment.

A microradiographic investigation of cancellous bone healing after irradiation and hyperbaric oxygenation: a rabbit study.

PURPOSE: To analyze the effect of irradiation on cancellous bone healing at different times after irradiation and to study if hyperbaric oxygen therapy (HBO) would affect the bone healing capacity, when delivered directly after irradiation. METHODS AND MATERIALS: Rabbits were given a single dose of 15 Gy (60)Co radiation to one hind leg, the other hind leg serving as control. A standardized defect through the femoral metaphysis of the rabbits was created by a trephine drill biopsy at different times after irradiation. New bone formation in the defect was evaluated by a new biopsy through the previous defect after a healing time of 8 weeks. The mineral contents of the biopsies were analyzed by microradiography and microdensitometry. RESULTS: There was a large variation in the bone-forming capacity expressed as bone mineral content between the animals. No statistically significant differences could be detected regarding the effect of irradiation, HBO, or delayed surgery. Qualitative histology revealed more pronounced inflammation, fibrosis, and bone resorption in the irradiated bone. CONCLUSIONS: No definite conclusions can be drawn from the results of this study, however it might be hypothesized that cancellous bone recovers faster than cortical bone from radiation trauma.

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.

Measurement of bone metal contact (BMC) in retrieved maxillofacial osseointegrated implants.

Eighteen screw-shaped extraoral osseointegrated implants retrieved from 10 patients were analysed by microradiography. Retrieved implants were trephined with a border of surrounding bone, fixed, embedded in epon plastic, ground and processed for microradiography. The reasons for retrieval were unexplained pain (n = 4), inability to cope with the implants (n = 2), fracture of central screw (n = 2), skin penetration problems (n = 1) and trauma (n = 1). The study group comprised six males and four females with a mean age of 53.4 years (range: 9-81 years). All implants were clinically stable at the time of removal, and mean osseointegration time was 3 years (range: 1-5 years). Six implants were removed from the temporal bone, five from the frontal bone and seven from the maxilla. Bone metal contact was estimated to vary between 27% and 83%. Bone metal contact was lower in the frontal bone compared to the temporal bone or maxilla, and was further reduced after preoperative irradiation. Longer osseointegration time increased bone metal contact, as did increased age up to 60 years. It is concluded that extraoral osseointegrated implants in humans may integrate morphologically as well as clinically. By microradiography it was possible to define bone metal contact in the region of implant installation.

Osseointegrated implants in children.

This study was undertaken on 86 children aged 15 years or lower scheduled for installation of osseointegrated implants. Of these, 64 had implants installed for bone-anchored hearing aids (BAHA) or episthesis. 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 3-4 months in between. Available bone thickness averaged 2.5 mm, and lack of bone necessitated bone augmentation in 12 patients. Forty-five percent of the implants were installed in contact with the dura, sigmoid sinus or an air cell. Of 129 installed fixtures, 6.2% were implant failures. Adverse skin reactions appeared in 7.6% of patients over a 17-year follow-up period. Revision surgery was undertaken in 30% of patients due to appositional growth of the temporal bone. It is concluded that implant failures and skin reactions in this population are comparable to those in an adult group of implant patients, whereas revision surgery is more common in children. Nevertheless, osseointegrated implants can be used with good functional and aesthetic outcome in children.

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.

Microradiographic study of retrieved craniofacial osseointegrated implants.

In this study 18 screw-shaped extraoral osseointegrated implants retrieved from 10 patients were analyzed. The reasons for retrieval were: unexplained pain (n = 4); inability to cope with the implants (n = 2); fracture of the central screw (n = 2); skin penetration problems (n = 1), and trauma (n = 1). Retrieved implants were trephined with a border of surrounding bone, fixed, embedded in epon plastic, ground and processed for microradiography. The study group comprised 6 males and 4 females with a mean age of 53.4 (range 9-81) years. All implants were clinically stable at the time of removal, and the mean osseointegration time was 3 (range 1-5) years. Six implants were removed from the temporal bone, 5 from the frontal bone, and 7 from the maxilla. By microradiography, it was found that all retrieved implants were surrounded by a lamellar type of bone with haversian systems, vascular channels, osteocyte lacunae, and in some specimens regeneration and resorption areas. Bone metal contact was estimated to vary between 27 and 83%. Bone metal contact was lower in the frontal bone compared to the temporal bone or maxilla, and was further reduced after preoperative irradiation. Longer osseointegration time increased bone metal contact, as did increased age up to 60 years. It is concluded that extraoral osseointegrated implants in humans may integrate morphologically as well as clinically. By microradiography it was possible to define bone metal contact in the region of implant installation.

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.