An in vitro biomechanical comparison of the breaking strength and stiffness of polydioxanone (sizes 2, 7) and polyglactin 910 (sizes 3, 6) in the equine linea alba.

The study investigates the failure strength and stiffness of four types of suture materials in equine abdominal tissue, or linea alba, and finds that larger suture materials display higher resistance before breaking. The study concludes that 7 PD, a particular type of suture, appears ideal for closing equine linea alba due to its high initial breaking strength and longer strength retention.

Research Design and Methods

• The research employed a randomized complete block design with equine linea alba collected from 12 adult horses, averaging a weight of 475 kg and 10 years of age.
• The abdominal fascia, inclusive of the linea alba, was segmented into right and left halves. Each half was then subdivided into four 5-cm sections, which were each assigned randomly to one of the four suture materials: 2 PD, 3 PG, 6 PG, and 7 PD.
• The breaking strength and stiffness of each suture were evaluated using a single cycle to failure test, at a distraction rate of 100 mm/min.
• The differences in breaking strength and stiffness across the four suture materials were determined using a mixed linear model.

Results

• In 94 out of a total 96 test sections, failure occurred due to suture failure and not the linear alba tissue.
• There were significant variations in both failure strength and stiffness among the different types of suture materials.
• The highest breaking strength was exhibited by 7 PD at 316.8 N, followed by 6 PG at 281.3 N, 3 PG at 229.9 N, and lastly, 2 PD at 193.0 N.
• In terms of stiffness, 6 PG recorded the highest value at 14 N/mm, with 3 PG following at 12.7 N/mm, then 7 PD at 10.1 N/mm, and 2 PD at 7.2 N/mm, being the least stiff.
• Suture breaking strength and stiffness were unaffected by linea alba thickness, individual horse variation, the half of the linea alba used, or position on the abdominal wall.
• Notably, the major mode of failure for the sutures was adjacent to the knot, accounting for approximately 90.4% of the failures.

Conclusion

• The suture material was found to be the failure point more often than the tissue of the linea alba itself.
• Both breaking strength and stiffness were higher in larger suture materials compared to their smaller counterparts, with these parameters also dependent on suture material and size.
• Bearing in mind its superior initial breaking strength and prolonged in vivo strength retention, 7 PD was deemed a suitable choice for suturing the equine linea alba when maximum short-term failure strength is needed.