Application of polylactic acid (PLA) in absorbable sutures

1. Polylactic acid suture
PLA (H-[OCHCH 3 CO]n-OH), also known as polylactide, is a type of polymer polymerized from the fermentation product of microorganisms, L-lactic acid (L stands for levorotatory) as a monomer. Toxic, non-irritating, with good biocompatibility, biodegradable absorption, high strength, no pollution to the environment, in the field of medical devices, polylactic acid is the preferred medical functional polymer material, and it is also a preferred absorbable surgery The suture material has been approved for clinical use by the US FDA.
Nonetheless, studies have found that when the average molecular weight of PLA is lower than 20,000, the incidence of aseptic inflammation is higher; high molecular weight PLA can delay but not eliminate this. The reason for this may be
Acidic substances are produced during the degradation process, resulting in a drop in pH. Therefore, basic substances such as calcium carbonate, etc. can be introduced into the polymer to eliminate this reaction. For example, in HA/PLA composites, the presence of HA can not only slow down the hydrolysis of PLA and prevent the occurrence of aseptic inflammation, but also make up for the lack of mechanical strength of PLA.
The degradable PGLA is a new type of polymer material obtained by copolymerizing glycolide and lactide in a certain proportion. It has good flexibility, and its strength and feel are better than ordinary synthetic fibers. It can be maintained for three or four weeks, and the absorption cycle is about three months, which allows enough time for the surgical incision to heal.
2. Advantages and disadvantages of polylactic acid in medical
The advantages of polylactic acid in medical applications: First, it has complete biocompatibility, and the decomposed intermediate products and final products are non-toxic and harmless to the human body, and no teratogenicity, etc.; Its knotting and knot-holding properties meet the requirements of clinical surgery; thirdly, the product is stable, easy to store, resistant to disinfection, and easy to sterilize. In the body, after implantation for a certain period of time, the strength remains stable, which is conducive to wound healing; fourthly, in the wound healing It is automatically degraded and absorbed after the treatment, and there is no need to remove the stitches. Fifth, there are few adverse reactions after surgery, and the wound is less prone to scarring and agglomeration, and the infection rate is low.
The shortcomings of polylactic acid in medical use: First, it is too hydrophobic, which is not conducive to the adhesion, growth and differentiation of human cells; Second, the degradation products are acidic, which may lead to adverse reactions of cells during clinical use; Third, the base in the molecular chain The group is single, and it is difficult to compound with biologically active molecules.
3. The development prospect and prospect of polylactic acid
Polylactic acid polymer materials are highly valued in the field of medical research because of their good biocompatibility and degradability. Although polylactic acid has many shortcomings in medical treatment, it can be modified by post-treatment processes and coatings. More extensive and more potential for development. In the medical field, PLA is not only used to make absorbable sutures, its fiber braid or membrane material can be used as human tissue repair materials, such as anti-adhesion membranes for tendon tissue, periosteal growth isolation membranes, and can also be used for controlled drug release. Carrier, artificial skin, bone repair substitute material. It has also been widely used in tissue engineering research, and has made certain progress in tissue engineering research such as cartilage, skin, bone, tendon, liver, and tubular structures.