Mesh prostheses

Polymers are widely used as implant materials because they have physical properties that are similar to those of natural tissues. Examples are long-term and shortterm implants such as blood vessels, heart valves, membranes, mesh prostheses, corneas, tracheal prostheses, dental materials, parts of the nose and ear, knee and hip joints, and others. The synthetic polymers used include polyethylene (PE), particularly ultrahigh molecular weight PE (UHMWPE), poly(ethylene terephthal-ate) (PET), poly(tetrafluoroethylene) (PTFE), polyurethane (PU), and poly(methyl methacrylate) (PMMA). The necessary sterilization before implantation can be performed by y-irradiation, heat (steam), or chemical treatment (ethylene oxide), which should not cause any structural degradation of the polymers. Current challenges in research include the development of biomimetic materials that match both the mechanical and biological properties of their natural counterparts. 

Adler, R.H., Pelecanos, N.T., Geil, R.G., Ro.senzeig, S.E. and Thorsell, II.G., (1962) Collagen mesh prosthesis for wound repair and hernia reinforcement. Surgical Forum, 13, 29-31. 

Figure 2.5 (a) Umbilical cord with central vein and smaller snrronnding arteries (left panel). This is clearly demonstrated on the microscopic view (right panel) (b) human umbilical cord vein manufactured as a vascular prosthesis including an outer Dacron mesh (c) retention of graft architecture with glutaraldehyde processing at 2 weeks, 8 months, and 2 years. 

Okumura N., Nakamura T., Natsume X, Tomihata K., Ikada Y. Shimizu Y. (1994) Experimental study on a new tracheal prosthesis made from collagen-coniugated mesh, tourned of Thoracic (jf Cardiovascular Surgery, 108, 337-45. 

Recent technological advances in the last two decades have led to the development of self-expanding or expandable metallic mesh stents. These stents represent the latest technology for the treatment of malignant and benign airway obstructions. A stent can be described as a tubular prosthesis that maintains luminal patency and a predefined luminal diameter of a tubular structure by opposing radial forces to extrinsic or intramural compressive forces. Thus, a stent provides internal support for luminal patency. 

Tendons and Ligaments.—Results of experimental replacement of partial or total collateral ligaments with Marlex (polyethylene) mesh in the knees of dogs have been reported." Papers presented at the Israel National Council of R. D. Conference at Arad in 1976 (dealing with medical applications of polymeric fibres) have been published in Applied Polymer SymposiaP A more recent review considers the work done to date on artificial tendons. The overall implications of the work are discussed in terms of prosthesis durability, attachment to bone and tendon, mechanical properties of the prostheses, and the volume of scar tissue generated. 

Regarding Y-shaped tubular scaffolds, a limited experimentation has been conducted. Sekine et al. [ 130] implanted a Y-shaped Marlex mesh tube in dogs. The tubes were reinforced with polypropylene spiral and coated with collagen from porcine skin. Six of the 20 dogs have survived after experimentation. The main causes of death were obstmction of the main bronchus, omental necrosis, and air leakage. The same prosthesis was grafted as tracheobronchial bifiircalion replacement after 5 years, the scaffold was completely incorporated. Neitho- stenosis nor dehiscence was observed, and a functional airway was revealed [131]. 

N. Okumura, T. Nakamura, Y. Shimizu, T. Natsume, Y. Ikada, Experimental study of a new tracheal prosthesis made from coUagen-grafted mesh, ASAIO Trans. 37 (3) (1991 Jul-Sep) M317-M319. 

Fig. 1 Meshed reconstructed bones and designed prosthesis in three different flexion angle...

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