Old habits tie hard: an in vitro comparison of first-throw tension holding in Polyglycolic acid (Dexon S) and Polyglactin 910 (Coated Vicryl).

PURPOSE

To compare the first-throw tension holding property of two braided absorbable sutures commonly used in oculoplastic surgery.

METHODS

The study was an in vitro experimental model. 6/0 Polyglycolic acid (Dexon S) and 6/0 Polyglactin 910 (Coated Vicryl) were compared using an experimental model to determine first-throw knot security. A polypropylene suture (Surgipro 2) was included as a benchmark to judge the apparatus by, ensuring that our experiment could be designed independently of the test suture materials. Increasing metric loads were applied to the first double throw of a surgical knot. Each suture was tested to the point of knot slipping and the critical tension recorded. All the sutures were kept wet during use. Three variations of the experiment were undertaken: experiment 1 -- two metal loops brought together by the test suture; experiment 2 -- two strips of tissue brought together by the test suture; and experiment 3 -- a knot tied over a metal bar coated in tissue. The tissue used was processed cross-linked porcine dermal collagen (Permacol). Each experiment was repeated three times for each suture type and the mean value taken.

RESULTS

Experiment 1: Dexon S 12.2 g (11, 12, 13.5), Coated Vicryl 2.5 g (2.5, 2.5, 2.5) and Surgipro 2 2.3 g (2, 2, 3); experiment 2: Dexon S 33.33 g (30, 35, 35), Coated Vicryl 25 g (25, 25, 25) and Surgipro 2 5 g (5, 5, 5); experiment 3: Dexon S 100 g (100, 100, 100), Coated Vicryl 56.667 g (60, 55, 55) and Surgipro 2 5 g (5, 5, 5).

CONCLUSIONS

Dexon S-braided absorbable suture has significantly better first-throw knot security when compared with Coated Vicryl. This is an important property when suturing tissues under tension as it minimizes slippage before the locking throw is tied.