Evaluation of 5 knots and 2 suture materials for arthroscopic rotator cuff repair: Very strong sutures can still slip

Purpose: To compare a standard suture material with a newer material using multiple arthroscopic knot configurations and to evaluate the biomechanical performance of a new sliding-locking knot compared with 4 surgical standards. Type of Study: Controlled laboratory study. Methods: Five knots were evaluated (Weston, Tennessee, Duncan, SMC, and the new San Diego knot) using 2 suture materials, No. 2 Ethibond (Ethicon, Somerville, NJ) or No. 2 Fiberwire (Arthrex, Naples, FL). Eight samples were tested for each knot-suture configuration. Samples were pretensioned to 10 N and then loaded from 10 to 45 N for 1,000 cycles. Intact knots were loaded to failure. Results: Fiberwire had significantly higher load-to-failure (276 +/- 24 N) compared with Ethibond (111 +/- 13 N) (P < .001), although there was no significant difference as a function of knot configuration. Of the 40 Fiberwire knots, 3 failed by early slippage during cyclic loading and 8 slipped at very low tension during load-to-failure. None of the Ethibond knots and none of the San Diego knots failed by early slippage. Conclusions: Surface characteristics and suture construction affect the tendency for knot slippage. Clinical Relevance: Surgeons should understand the impact of handling characteristics, frictional properties, and ultimate failure load when selecting suture materials and knots for arthroscopic repair.