Suture permanent

Sutures are required to hold tissues together until the tissues can heal adequately to support the tensions exerted on the wound duting normal activity. Sutures can be used ia skin, muscle, fat, organs, and vessels. Nonabsorbable sutures are designed to remain ia the body for the life of the patient, and are iadicated where permanent wound support is required. Absorbable sutures are designed to lose strength gradually over time by chemical reactions such as hydrolysis. These sutures are ultimately converted to soluble components that are then metabolized and excreted ia urine or feces, or as carbon dioxide ia expired air. Absorbable sutures are iadicated only where temporary wound support is needed. 

Artificial biologies, whelher soff or hard, can be categorized as eifher temporary (short term) or permanent (long term) in their intended application. Most, but certainly not all, polymers for biomedical applications are of the short-term type and include sutures, drug delivery devices, temporary vascular grafts and stents, tissue scaffolds. 

Plastic sutures (and supporting meshes) are, depending on the location of their application on or in the body, can be permanent or biodegradable in time with body fluids, and so additive and biocompatibility issues should be considered critically and carefully. 

Polyamide monofilament sutures show smooth surhices wifti a circular cross-section before implantation (see Fig. lb). No fibrous tissue cqisule was observed on the suture surface or around the knot post implantation. This is contributed to its smooth surface characteristic. However a closer examination of the opened knot shows flattening of the knot region (see Fig. 7). This is attributed to the ductile structure of polyamide sutures. It shows permanent deformation due to lateral forces exerted during loading. The rupture of the melt-spun synthetic fibres like polyamide is dominated by yield. Plastic yield of material causes the crack to open into a V-notch, vduch propagates steadily into the specimeiL This typical ductile fixture was seen at the broken ends, alter tmisile tests, both before and er implantation (see Fig. 8). 

Absorbable polymer sutures for wound closure appeared in the 1970s. These PGA-based sutures registered tremendous growth, a trend which continues even now. Since the wound should be closed for healing, which can be easily triggered by a transition from temporary to permanent shape, the interest turned to smart sutures making use of the SM behavior. The attribute smart may be related to the antimicrobial and healing activities, set by the incorporation of suitable additives into the sutures [80, 81]. 

Employers should take appropriate preventative measures against occupational exposure. These include engineering controls and work practice controls. Examples of engineering controls include biohazard hoods, puncture-resistant sharps containers, mechanical pipette devices, and other devices that permanently remove the hazard or isolate individuals from exposure. Organizations must evaluate and incorporate new safer devices including needleless devices, needles with sheaths, and blunt suture needles. Work practice controls must include hand washing policies, sharps handling procedures, proper waste disposal techniques, and other actions that would reduce the likelihood of exposure. 

All polymers used for making barbed sutures exhibit viscoelastic behavior. Their mechanical performance may be associated with hysteresis, and the barb may experience permanent deformation even when the loads and extensions are well below the elastic limit. One such property, which can be useful, is stress relaxation. This can be seen when a barbed suture is sewn across a wound or incision which contains barbs distributed along its entire length. The suture can relax and each barb can conform independently to the optimal required forces in each region of the suture. Stress relaxation serves as a mechanism to eliminate unnecessary forces and stress concentrations that the suture might exert on the wound tissue. This can contribute to reduced trauma and tissue necrosis, foster quicker healing and reduce scar tissue formation. 

The question whether silk fibroin filaments are resorbable or permanent is open to interpretation. Having a polypeptide chemical structure, silk fibroin, like any other protein, is susceptible to proteolytic degradation, and will become weaker and eventually over a period of 2 years will be totally resorbed in vzvo. However, given the definition for an absorbable suture in the United States Pharmacopeia as a material that loses most of its tensile strength within 60 days post-implantation silk can therefore be classified as a permanent biomaterial. 

Fig. 4.68 Atrial lead placement through atriotomy and purseslring suture. Atrium and ventricular electrodes are positioned and the atriotomy is secured. (Westerman GR, Van Devanter SH. Transthoracic transatrial endocardial lead placement for permanent pacing. Ann Thorac Surg 1987 43(4) 445-446, with permission.)...

Fig. 6.42 Permanent active-fixation pacing electrode placed via the right internal jugular vein. Suture sleeve securing the lead to the neck. Lead connected to the explanted pulse generator, which is sutured to the anterior chest.

The biostable materials such as metals, ceramics, glasses, polymers, and stable composites are intended to stay in a body for the patient s lifetime and function appropriately. They should be physiologically inert, cause only minimal response of the surrounding tissues, and retain their properties for years in vivo. Biostable materials have wide application in permanent prostheses such as joint prostheses, sutures, and other implants. 

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