Microscopical Characterization of Poly‐L/D‐Lactide (PLDLA) 96/4 Sutures in the Achilles Tendon of Rabbits

Common Achilles tendon ruptures are usually not fixed by absorbable sutures due to limitations in their strength properties. Modern technology has made it possible to develop bioabsorbable sutures with prolonged strength retention. To evaluate histologically tissue reactions and biodegradation of poly-L/D-lactide (PLDLA) sutures implanted in Achilles tendon of rabbits. Fifteen rabbits were operated on and killed within a time schedule of 2, 6 and 12 weeks, with five rabbits in per period. PLDLA monofilament sutures (Tampere University of Technology, Tampere, Finland) were implanted inside the rabbit medial gastrocnemius tendon for biocompatibility testing. Polyglyconate (4.0) monofilament sutures (Maxon®, Cyanamid of Great Britain Ltd., Gosport, UK) with the same diameter were implanted in the contralateral tendon. The histology was studied in hard-resin embedded samples and the thickness of the encapsule membrane was determined histomorphometrically. PLDLA have significantly smaller capsule formation around each fiber in tendon than Maxon® sutures. The mean capsule thicknesses around PLDLA sutures was 5.26, 11.66, and 10.63 after 2, 6, and 12 weeks respectively. The mean capsule thicknesses around Maxon® sutures was 13.22, 80.97, and 17.59 after 2, 6, and 12 weeks, respectively. In conclusion, by 12 weeks the PLDLA sutures implanted intratendineously formed thinner fibrous capsule than Maxon® sutures of same diameter. The suture materials were not degraded by 12 weeks. Acknowledgments:  Research funds from the Technology Development Center in Finland (TEKES, Biowaffle Project 40274/03 and MFM Project 424/31/04), the European Commission (EU Spare Parts Project QLK6-CT-2000-00487), the Academy of Finland (Project 73948) and the Ministry of Education (Graduate School of Biomaterials and Tissue Engineering) are greatly appreciated.