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Biomedical subjects

G Granström

Publications and source records attributed to G Granström.

At least 19 recordsLinked to original sources
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↗
PubMed2001

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.

Adolescent↗
PubMed2000

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.

Animals↗
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

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.

Adolescent↗
PubMed2000

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.

Adolescent↗
PubMed2000

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.

Acoustic Stimulation↗
PubMed2000

A histomorphometric and biomechanical study of the effect of delayed titanium implant placement in irradiated rabbit bone.

BACKGROUND: The time interval from irradiation to implant surgery has been considered an impact factor for implant integration in irradiated bone and the importance of a long interval between the radiation trauma and reconstructive bone surgery has been suggested. PURPOSE: The present study was undertaken to histomorphometrically and biomechanically analyze the effect of delayed implant placement on bone healing around titanium implants in irradiated bone. MATERIALS AND METHODS: Rabbits were given a single dose of 15 Gy Cobalt60 radiation to one hind leg, the other hind leg serving as a control. Titanium screws were inserted into the femur and tibia directly and at 12 weeks and 52 weeks after irradiation. The implants were evaluated after a healing time of 8 weeks. The torques necessary for removal of the implants were measured. Histomorphometry with respect to bone-metal contact and amount of bone surrounding the implants was performed. RESULTS: The biomechanical force necessary to unscrew the titanium implants in the irradiated bone was significantly increased after a resting period of 1 year between irradiation and implant placement, compared to direct implant placement. The histomorphometric evaluation showed an improvement of bone healing around the implants in the irradiated bone, both after a resting period of 12 weeks and after 1 year compared to direct implant placement. CONCLUSIONS: It is concluded that a relatively long interval between irradiation and reconstructive bone surgery will improve osseointegration of titanium implants in irradiated rabbit bone.

Animals↗
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

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

Osteoradionecrosis of the mandible: a microradiographic study of cortical bone.

We undertook a microradiographic study in osteoradionecrotic mandibular bone to estimate the number of vascular channels in the compact bone, number of resorption areas, and number of regeneration areas. Normal mandibles had a similar number of vascular channels/vision field compared with compact bone in other parts of the body. Irradiation itself did not significantly alter this number. After osteoradionecrosis had developed in the mandible, the number of vascular channels increased (p = 0.02). Treatment with hyperbaric oxygen further increased the number of vascular channels/vision field (p < 0.003). The normal mandible had no resorptive or regenerative areas, either before or after radiotherapy. The osteoradionecrotic mandible, however, had an increased number of resorptive as well as regenerative areas/vision field. Fluorescence as an indication of incorporation of tetracycline was seen in the regenerative areas of all osteoradionecrotic specimens treated with doxycycline. The process started from the vascular channels, periosteum, and endosteum. We conclude that the compact bone of mandibular osteoradionecrosis has high metabolic activity with active resorption and regeneration of bone and the limitation of the blood supply through cortical vascular channels, seems to be only one of many important factors.

Adult↗
PubMed1999

First and second branchial arch syndrome: aspects on the embryogenesis, elucidations, and rehabilitation using the osseointegration concept.

BACKGROUND: The osseointegration concept has dramatically changed the possibility of rehabilitating patients with craniofacial defects due to branchial arch syndromes. PURPOSE: This article describes some problems related to the investigative routines and rehabilitation of individuals with malformations of the first and second branchial arches of the craniofacial region. Animal model systems have increased the knowledge of basic embryonic processes that can explain the extent of the malformations. Though most clinical first and second branchial arch syndromes are likely to be caused by sporadic mutations, inherited syndromes occur and also teratogenically induced syndromes are known. Prenatal diagnosis ruling out heredity and exogenous influence seems possible in the future. The possibility of preventing and alleviating fulminant syndromes prenatally also could be conceivable in the future. PATIENTS AND METHODS: The rehabilitation process starts early after birth and should involve a team of specialists including clinical geneticists, pediatricians, audiologists, plastic surgeons, maxillofacial surgeons, otosurgeons, anaplastologists, speech pathologists, pedodontists, and orthodontists. With the development of the osseointegration concept in which craniofacial prostheses and hearing aids can be adapted on implants anchored in the craniofacial skeleton, a new field in the rehabilitation of these malformations has opened. RESULTS: Important aspects in the use of the osseointegration concept include determination of the lowest age for implant surgery, accessibility of adequate bone for implants, the growth of the craniofacial skeleton during childhood, and the possibility for the patient and his or her parents to care for the skin penetration. Adverse tissue reactions, durability of craniofacial prostheses, and the possibility of unknown adverse reactions to metal implants in the body over a long time are other aspects of concern. CONCLUSIONS: Patients with branchial arch syndromes benefit from a well-planned multidisciplinary rehabilitation process in which osseointegrated bone-anchored hearing aids and bone-anchored ear prostheses can be useful tools.

Adolescent↗
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↗