Bone restoration

Kamel (21) at Drexel University has been developing a bone restorative using an alumina- poly(acrylic acid) composite produced by exposing an aqueous mixture of the blend to y radiation of 1 MRad (Figure 8). The porosity and crosslink density of the system were varied over wide ranges by varying monomer concentration and a heat treatment step to form anhydrides. 

Figure 8. Radiation-processed poly aery lie acid (PA A) composites for bone restoration. (Reprinted from Ref. 21. Copyright 1977.)...

Jackson-Burrows, H., Wilson, J. N. and Scales, J. T., Excision of Tumors of Humerus and Femur with Restoration of Internal Prostheses , Journal of Bone and Joint Surgery, STB, 148 (1975)... 

Dicarboxymethyl chitosan and 6-oxychitin sodium salt, applied to femoral surgical defects for 3 weeks produced a good histoarchitectural order in the newly formed bone tissue. The spongious trabecular architecture was restored in the defect site. The association of the chitin derivatives with the osteoblasts seemed to be the best biomaterial in terms of bone tissue recovery [128]. 

Hip replacement surgery is now routinely used to relieve pain and restore mobility in patients suffering from osteoarthritis. In this condition the surfaces of bone in contact with each other within the joint become worn and the layer of lubricating cartilage disappears. This makes movement of the joint both difficult and painful. By replacing the hip with an artificial joint patients stop experiencing pain and are once again able to move freely. 

The glass polyalkenoate cement uniquely combines translucency with the ability to bond to untreated tooth material and bone. Indeed, the only other cement to possess translucency is the dental silicate cement, while the zinc polycarboxylate cement is the only other adhesive cement. It is also an agent for the sustained release of fluoride. For these reasons the glass polyalkenoate cement has many applications in dentistry as well as being a candidate bone cement. Its translucency makes it a favoured material both for the restoration of front teeth and to cement translucent porcelain teeth and veneers. Its adhesive quality reduces and sometimes eliminates the need for the use of the dental drill. The release of fluoride from this cement protects neighbouring tooth material from the ravages of dental decay. New clinical techniques have been devised to exploit the unique characteristics of the material (McLean Wilson, 1977a,b,c Wilson McLean, 1988 Mount, 1990). 

Therapeutic modalities for amenorrhea are targeted at restoring the normal menstrual cycle. The goals of treatment are to preserve bone density, prevent bone loss, and restore ovulation, thus improving fertility as desired. Amenorrhea resulting from conditions contributing to hypoestrogenism also may affect quality of life via the induction of hot flashes (premature ovarian failure), dyspareunia, and in prepubertal females, lack of secondary sexual characteristics and absence of menarche. 

Bone is one of the few tissues capable of self-regeneration during skeletal deficiency, but this regeneration is limited by the nature and size of the defect. In general, skeletal deficiency occurs as a result of trauma, tumor, bone disease, or abnormality. In the case of severe fracture, bone will not heal by itself. For this reason, artificial bone substitutes may be required to restore routine function without damaging living tissue, and the selection of the bone graft substitute is the most important factor for better performance in vivo. 

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