Preclinical and Clinical Applications of PLA Devices

The longest and the largest application of biodegradable polymers in medicine is in sutures. The synthetic polymer used for this purpose is mainly PGA or its copolymer with 

LLA (90 10), which were launched in 1970 and 1974, respectively [14, 15]. PDS sutures were also developed in 1981. Because PLLA fibers degrade very slowly, they are not suitable for sutures. However, in applications that require long retention of the strength, PLLA fibers are the preferred material. These include ligament and tendon reconstruction, and stents for vascular and urological surgery. 

FIGURE 27.2 Reconstmction of infraspinatus (IS) tendon by PLLA felt (F). SS indicates supraspinatus tendon (reprinted from Ref. 20 with permission from John Wiley Sons). 

FIGURE 27.3 Some designs of stents (reprinted from Ref. 21 with permission from Sangyo-Tosho). 

Nondegradable silicone stents are also commercially available. They can be removed more easily than metallic ones, but the large thickness of the tube can cause obstruction. Saito et al. [22] compared the biocompatibility and suitability of a tubular bioabsorbable knitted stent made of PLLA and a conventional silicone stent in normal rabbit airways. Three out of eight rabbits in the silicone stent group died within 4 weeks of implantation as a result of airway obstruction by secretions inside the stent lumen, whereas none of the rabbits in the PLLA stent group died from airway complications. 

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