Bone-anchored Device Research Articles

The Use of a Bone-Anchored Device as a Hard-Wired Conduit for Transmitting EMG Signals From Implanted Muscle Electrodes

The use of a bone-anchored device to transmit electrical signals from internalized muscle electrodes was studied in a sheep model. The bone-anchored device was used as a conduit for the passage of a wire connecting an internal epimysial electrode to an external signal-recording device. The bone-anchored device was inserted into an intact tibia and the electrode attached to the adjacent M. peroneus tertius. "Physiological" signals with low signal-to-noise ratios were successfully obtained over a 12-week period by walking the sheep on a treadmill. Reliable transmission of multiple muscle signals across the skin barrier is essential for providing intuitive, biomimetic upper limb prostheses. This technology has the potential to provide a better functional and reliable solution for upper limb amputee rehabilitation: attachment and control.

La distraction symphysaire : protocole simplifié

Severe mandibular incisor crowding with bone insufficiency is usually treated by dental extractions and orthodontic management. Symphyseal distraction was proposed to avoid tooth extraction. This technique is still considered as invasive, complex and unsafe. We evaluated symphyseal distraction to clarify its indications, and to suggest a simplified surgical protocol.Six patients were treated by symphyseal distraction: three with a bone-anchored device and three with a dental anchored one. Pre and postoperative inter-canine measurements and occlusal stability were analyzed.Postoperative inter-canine measurements increased from 3.4 to 6.8mm (mean 5.2mm). All patients were in Angle class I occlusion without complications. Dental anchored device simplified the surgical procedure.Symphyseal distraction with dental anchored device is a simple, efficient and reliable to treat severe transverse mandibular deficiency. The orthodontist can manage the procedure by himself and controls the whole expansion process according to specific requirements.

Transverse maxillary stability assisted by a transpalatal device: A retrospective pilot study of 9 cases

This retrospective pilot study assessed the transverse stability of an original surgical approach in nine patients with moderate transverse maxillary deficiency associated with a sagittal and/or vertical skeletal anomaly. During the one-stage surgical procedure, bi- or three-dimensional anomalies were corrected. Maxillary expansion was guided by a transpalatal bone-anchored device (TPD). Expansion measurements were made 1-2 months before surgery, 6 and at least 12 months after surgery. The transverse occlusion was corrected in all cases. After 12 months the gingival landmarks revealed an expansion range from -0.83 to +2.92 mm for the cuspids, +1.66 to +6.23 mm for the bicuspids and from +2.68 to +4.80 mm for the molars. For the occlusal landmarks, expansion ranged from -2.01 to +3.15 mm (cuspids), from +1.11 to +7.13 mm (bicuspids) and from +2.70 to +6.26 mm (molars). Cuspid expansion was significantly smaller than that of bicuspids and molars. This more posterior expansion was achieved through the surgical procedure. The transverse stability obtained with the aid of the bone-anchored TPD was satisfying. This preliminary study supports the principle of an original surgical approach, called 'Le Fort I--TPD', which combines a Le Fort I osteotomy with a controlled maxillary expansion.

Wertigkeit der BAHA-Testung für das postoperative Hörergebnis

Bone-anchored hearing aids provide a therapy option for patients with conductive and mixed hearing loss, with the possibility of audiological rehabilitation. Test rod and tension headband offer the patient a preoperative impression of their postoperative hearing. The aim of this study was to evaluate the tools available for preoperative assessment of candidates for bone-anchored hearing aids and to ascertain predictive audiometric values. Following implantation of a BAHA Compact system, sound and speech audiograms were performed in each of 16 patients with the bone-anchored BAHA device and with test rod and tension headband. Both with the BAHA and with the test devices, closure of the air-bone gap occurred and resulted in a clear improvement in hearing threshold and speech perception. The threshold increase with the BAHA was 9 dB greater on average (mean) than that measured with the test rod and the tension headband. Examinaation of speech perception indicated a mean advantage of 14-20% for the anchored BAHA system over the tension headband in monosyllabic testing. Preoperative testing before providing a BAHA system is a good way of predicting what level of hearing and speech perception can be expected after implantation.

Load bearing capacity of bone anchored fiber-reinforced composite device

The purpose of this study was to evaluate the push-out load-bearing capacity of threaded fiber-reinforced composite (FRC) devices for use as bone-anchored devices. The purpose was also to evaluate the possibility to use bioactive glass (BAG) granules on the experimental FRC devices in terms the mechanical behavior. Three experimental FRC devices (n = 15) were fabricated for the study: (a) threaded device with smooth surface; (b) threaded device with BAG granules (S53P4, Vivoxid Ltd, Turku, Finland) and supplementary retention grooves, and (c) unthreaded device with BAG granules. Threaded titanium devices were used as controls. The FRC devices were prepared from a light-polymerized dimethacrylate resin reinforced with preimpregnated unidirectional and bidirectional E-glass fibers (EverStick, StickTech Ltd, Turku, Finland). Experimental and control devices were embedded into dental plaster to simulate bone before the mechanical push-out test was carried out. ANOVA and Weibull analysis were used for the statistical evaluation. Threaded FRC devices had significantly higher push-out strength than the threaded titanium device (p < .001). The push-out forces exceeding 2,500 N were measured for threaded FRC devices with supplementary grooves and BAG coating. No thread failures were observed in any FRC devices. The unthreaded FRC devices with BAG lost 70% of glass particles during the test, while no BAG particles were lost from threaded FRC devices. It can be concluded that threaded FRC devices can withstand high push-out forces in the dental plaster without a risk of thread failure under physiological load.

Current Products and Practice

Bone anchorage is a promising new field in orthodontics and already a wide variety of bone anchorage devices (BADs) are available commercially. This review aims to assist clinicians by outlining the principles of bone anchorage and the salient features of the available systems, especially those that may influence the choice of a specific BAD for anchorage reinforcement.

Modulation of early angiogenesis by nitric oxide

undergone surgical placement of bone anchorage devices for orthodontic treatment. A total of 37 devices have been placed to date. In three cases, maxillary IMF screws were placed bilaterally in order to provide orthodontic anchorage. In the remaining 16 patients, specialized bone anchorage devices were used. Data collection was carried out during a retrospective review of each patient’s record, preoperative and postoperative radiographs, and patient and surgeon questionnaires completed during the perioperative period. Results: All participating surgeons rated the surgical procedure as very easy to moderately easy. The most challenging aspect of the surgical procedure was related to retraction during the placement of devices through small vertical incisions. Postoperative morbidity was characterized by minimal to mild pain and moderate degree of swelling. Postoperative complications included mucosal inflammation around the device (2 implants), fracture of one device, and failure of the monocortical screws securing the device (2 implants). Conclusion: The use of skeletal fixation devices for anchorage appears to be a promising adjunctive treatment for specific orthodontic indications. Our preliminary surgical experience has revealed easy surgical placement, minor postoperative morbidity, and a low rate of postoperative complications related to the implants.

The future of extra-oral implantology.

In this paper conclusions are drawn from the experiences of subjects presented in the previous studies in this issue. Indications for bone-anchored implants, the percutaneous passage, implant placement in irradiated tissues, and the psychosocial aspects of treatment are discussed in detail. The future of the extra-oral implantology is also discussed. There is some experience with using bone-anchored implants extra-orally, but both medical and dental staff and the patients themselves are reluctant to use them. In the future, this might change when the percutaneous passage is improved, when hyperbaric oxygen therapy is generally used, when there is more insight into all the possibilities and limitations of bone-anchored devices, and when their application is generally accepted.

Hearing Results With a Percutaneous Bone-Anchored Hearing Aid

The effectiveness of a percutaneous bone-anchored hearing aid was reported by Maxwell Abramson, MD, and colleagues from Columbia University (New York) at the Eastern Section meeting of the Triological Society in New York. Over a two-year period, nine patients received an implant of a percutaneous bone-anchored hearing aid that was developed at the University of Gothenburg (Sweden). This device is similar in principle to the bone-anchored device described by Hough, with the exception that the stimulation is percutaneous rather than transcutaneous. The authors suggest that the percutaneous device should be more powerful due to the more effective transfer of energy to the device. Patients with a conductive hearing loss of 40 dB or better, and with speech discrimination scores of at least 60%, are considered as candidates for this procedure. All patients had used the bone conduction hearing aid prior to implantation, had congenital aural atresia, had demonstrated problems with