Mandibular lengthening with an implanted motor-driven device: preliminary study in sheep.

Distraction osteogenesis with external or intraoral devices is an established method for lengthening human mandibles. In this preliminary study in three sheep a newly designed, fully implantable electromechanical device for mandibular lengthening was used. After osteotomy, the device was screw fixed to the mandible, and the power and control unit was inserted subcutaneously in the neck region. After a healing period of five days, the device was activated magnetically, allowing calibrated distraction steps of 0.04 mm/h, resulting in a total of 1.0 mm/day. Over a period of 14 days, a maximum mandibular lengthening of 13.6 mm could be achieved without transmucosal activation. Depending on stability of the screw fixation, membranous and/or cartilaginous bone formation was observed in the callus by radiological and histological evaluation. Further experimental research is ongoing to prove the clinical usefulness of this device.

[Distraction osteogenesis with a fully implantable system. Experimental study]. / Distraktionsosteogenese mit einem voll implantierbaren System. Experimentelle Studie.

Distraction osteogenesis using external or intraoral devices is an established method for lengthening the human mandible. In this preliminary study on sheep, a completely implanted device for mandibular lengthening is presented. After osteotomy of the mandible, the electromechanical device was fixed to the mandible and the power and control unit were inserted subcutaneously in the neck region. After a healing period of 5 days, the device was activated magnetically and allowed calibrated distraction steps of 0.04 mm/h, achieving a total of 1.0 mm per day. With this method, it was possible to lengthen the mandible automatically over a period of 14 days without transmucosal activation. In our study, this newly designed internal device was successfully used for distraction osteogenesis, and a maximum mandibular lengthening of 13.6 mm was achieved. Further research is necessary to achieve progression to human clinical application in the near future.

Battery-powered implantable nerve stimulator for chronic activation of two skeletal muscles using multichannel techniques.

Chronic activation of skeletal muscle is used clinically in representative numbers for diaphragm pacing to restore breathing and for dynamic graciloplasty to achieve fecal continence. The 3 different stimulation techniques currently used for electrophrenic respiration (EPR) all apply high frequency powered implants. It was our goal to make these stimulation methods applicable for EPR by a battery-powered nerve stimulator that would maximize the patient's freedom of movement. Additionally, the system should allow the implementation of multichannel techniques and alternating stimulation of 2 skeletal muscles as a further improvement in graciloplasty. Generally, the developed implantable nerve stimulator can be used for simultaneous and alternating activation of 2 skeletal muscles. Stimulation of the motor nerve is achieved by either single channel or multichannel methods. Carousel stimulation and sequential stimulation can be used for graciloplasty as well as for EPR. For EPR we calculated an operating time of the implant battery of 4.1 years based on the clinically used stimulation parameters with carousel stimulation. The multichannel pulse generator is hermetically sealed in a titanium case sized 65 x 17 mm (diameter x height) and weighs 88 g.

MYOSTIM-FES to prevent muscle atrophy in microgravity and bed rest: preliminary report.

Long-term flights in microgravity cause atrophy and morphological changes of skeletal muscles. Training with mechanical devices is insufficient regarding the required time to exercise and space for devices. The objective of this project is to develop a passive training method based on functional electrostimulation (FES) to preserve muscle mass and fiber composition with minimal impairment to the cosmonaut. For a pilot experiment on the MIR space station, a suitable 8 channel FES device was developed. It consists of electrode trousers that carry surface electrodes and cables, 2 interconnected 4 channel stimulators, and a laptop personal computer (PC) for stimulator programming and processing compliance data. An automatic extensive training of 4 muscle groups of the lower extremities is performed for 6 h/day, with 1 s on and 2 s off tetanic contractions at 20-30% of maximum tetanic muscle force. The synchronous activation of antagonists of the thigh and lower leg prevents uncoordinated movements.

Multifunctional implantable nerve stimulator for cardiac assistance by skeletal muscle.

Different methods are used, clinically and experimentally, to assist severely impaired heart function by means of skeletal muscle. The efficiency of these methods is restricted by skeletal muscle losing strength after transpositioning and during conditioning and not being sufficiently resistant to fatigue. This is mainly due to the nonphysiological activation of the nerves by electrical stimulation. We have developed a battery operated, ECG triggered multichannel implant that is capable of implementing various advanced stimulation techniques. The stimulator can activate 2 skeletal muscles via the motor nerves. It allows for application of multichannel stimulation methods, i.e., carousel stimulation and sequential stimulation, as well as the programming of optimized pulse trains. Synchronization delay and burst duration can be automatically and dynamically adapted to the heart rate. The multichannel stimulator is hermetically sealed in a titanium case. Its calculated life span on the basis of the integrated battery is 3-5 years, depending on the programmed stimulation parameters. The implant dimensions are 65 x 17 mm (diameter x height), and it weighs 93 g. The implant has been tested in vitro as well as in vivo.

[Pruritometer 1: Portable measuring system for quantifying scratching as an objective measure of cholestatic pruritus]. / Pruritometer 1: Portables Messsystem zur Quantifizierung des Kratzens als objektives Mass für den cholestatischen Pruritus.

Objective assessment of subjective symptoms such as pruritus always presents problems, which can often be resolved only indirectly. The objectification of pruritus was necessitated by a study on the efficacy of a serotonin antagonist used as treatment of cholestatic pruritus. In the present paper, a portable measuring system for the indirect objective assessment of pruritus via the quantification of scratching is described. A piezoelectric scratch-vibration sensor for attachment to the middle finger of the patient's dominant hand was developed. A sensor interface detects the scratching signals and generates pulses that are then summed in an adapted sports watch. The entire system-Pruritometer 1- is worn by the patient like a wrist watch, and is characterized by ease of handling. Acceptance by the patient is reported to be good. A statistically good correlation between measured (Pruritometer) and visually counted scratches was demonstrated. Pruritometer 2, which will enable scratch frequency and intensity distribution over time to be determined, is presently being developed.