Bone growth stimulators

The U.S. Food and Drug Administration approved several electrical bone growth stimulators, primarily for fractures at the middle of long bones, such as a tibia (shinbone) that has not healed in at least nine months. Also, the mechanisms of healing may not be understood completely manufacturers studies have shown that the device did, in fact, affect cellular processes. 

Demand pacemakers are very low current devices, requiring only 25-50 jiW for sensing and 60-100 pW for stimulation. In contrast, implanted ventricular defibrillators (Fig. 1.3) must be able to deliver short electric pulses of 25-40 J (e.g. 2 A at 2 V for 10 s) which can shock the heart into normal rhythm, and hence require a much higher rate battery. The most common system is a lithium-silver vanadium oxide cell with a liquid-organic based electrolyte. More than 80 000 such units have been implanted. Implanted drug delivery devices also use lithium primary batteries, as do neurostimulators and bone growth stimulators. 

Other devices that use IAII2 cells are implantable bone growth stimulators [15] and an implantable electromechanical hearing system [16]. 

A conflict arises from two claims the first, that fluoride stimulates new bone growth and hence is useful therapeutically in controlling osteoporosis, and the other, that it is the cause of the increasing prevalence of hip fractures in the elderly [6]. Fluoride is currently not recommended for the treatment of osteoporosis, although slow release fluoride therapy is reportedly beneficial. The long-term benefit of the latter is unknown [7]. 

The successful isolation of primary cells is dependent on several factors, some of which are not subject to optimization, such as species, type of tissue, age and sex of donor, and presence of genetic modifications (e.g., knockout animals). Other factors such as the dissociation medium, enzymes and concentrations, temperature, and incubation times can be optimized to ensure the quality and consistency of a primary or cell line preparation. The identification and availability of key growth factors is an important determinant of which primary cells can be maintained in culture. For example lactoferrin is a pleiotropic factor with potent antimicrobial and immunomodulatory activities. Recently it has been shown that lactoferrin at physiological concentrations can also promote bone growth, potently stimulating the proliferation and differentiation of primary osteoblasts (Naot, 2005). 

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