Synthesis of PLA–poly(ether urethane)–PLA copolymers and design of biodegradable anti-adhesive membranes for orthopaedic applications

Abstract

Peritendinous adhesions cause chronic pain and disability. Leading causes are trauma to tendons and surrounding tissues and immobilization after surgery. Adhesions occur between 24 hours to 6 weeks after surgery. Anti-adhesion barriers are currently the best option available to prevent peritendinous adhesions, but are ineffective and difficult to use. We developed an anti-adhesive membrane that can be easily applied during tendon surgery and effectively prevent adhesions. The membrane is based on a new triblock copolymer, is non-toxic, can be bio-eliminated, and has a degradation rate of more than 6 weeks for optimal anti-adhesion effect. We synthesized and characterized poly(ether urethane) (PEU) from poly(ethylene glycol). Triblock copolymers poly(lactic acid)–PEU–poly(lactic acid) (PLA–PEU–PLA) were then synthesized from PEU with PLA blocks of different lengths, and characterized. The membranes were shaped by hot molding and their mechanical properties, contact angle, water uptake, the kinetics of in vitro degradation and cytotoxicity were studied. Mechanical properties were developed according to the needs of orthopaedic surgeons. Results showed that membranes maintained their filmogenic integrity, have a degradation rate for optimal adhesion prevention, can be bioeliminated and biocompatible suggesting that they could be safely and effectively used as anti-adhesion orthopaedic devices. These results support the use of PLA–PEU–PLA membranes as a medical device, however, the effectiveness of the membranes in vivo needs to be further evaluated. A future study using an in vivo rat model of postoperative peritendinous adhesions is currently being developed.