The three tested knots were taught to 16 of the 20 orthopaedic surgery residents at our institution by a fellowship trained sports medicine orthopaedic surgeon, the instructor. Four of the twenty residents were excluded due to scheduling conflicts. The cohort consisted of four PGY1, three PGY2, four PGY3, one PGY4, and four PGY5 orthopaedic surgery residents. There were 14 males and 2 females. Knots tied at time zero and at seven days later by all subjects were compared and found to have no difference in failure method or failure rate. Therefore, knots tied at the original training session and after the one-week washout period were grouped together for statistical analysis.
Dynamic cyclic loading
The Weston knot demonstrated the highest dynamic failure rate (10.4%) during cyclic loading compared with the surgeons (8.3%) or SMC knot (3.2%). There was no apparent effect of resident training on dynamic failure of any knot during cyclic loading. There was no difference in conditioning elongation between surgeon’s (p = 0.343), Weston (p = 0.486), or SMC knots (p = 0.200) tied by PGYI and PGYV residents (Fig. 2). Conditioning elongation of the surgeon’s, Weston, and SMC knots tied by the orthopaedic sports medicine fellow were 0.11 mm, 0.12 mm, and 0.38 mm, respectively.
Load to clinical failure
Clinical failure loads of the surgeon’s, Weston, and SMC knots as tied by PGYI residents were 103.8 ± 7.9 N, 84.0 ± 10.7 N, and 86.0 ± 28.5 N. For the PGYV residents, clinical failure loads for the same knots were 131.0 ± 19.5 N, 110.1 ± 38.6 N, and 98.4 ± 10.1 N. There was no difference in clinical failure load as a function of resident training for any knot (p > 0.114). The clinical failure loads of the surgeon’s, Weston, and SMC knots as tied by the orthopaedic sports medicine fellow were 115.3 N, 112.9 N and 110.2 N, respectively.
When grouping all knots together, the clinical failure loads of the surgeon’s, Weston, and SMC knots were 109.6 ± 28.6 N, 99.6 ± 29.7 N, and 99.4 ± 26.5 N. These differences were not statistically significant (p = 0.490).
Ultimate load to failure
Ultimate failure loads of the surgeon’s, Weston, and SMC knots as tied by PGYI residents were 195.2 ± 30.4 N, 190.7 ± 38.3 N, and 219.9 ± 63.2 N, respectively (Fig. 3). For the PGYV residents, ultimate failure loads for the same knots were 232.9 ± 32.4 N, 215.8 ± 51.0 N, and 247.2 ± 61.4 N, respectively. There was no difference in ultimate failure load as a function of resident training for any knot (p > 0.200). The ultimate failure loads of the surgeon’s, Weston, and SMC knots as tied by the orthopaedic sports medicine fellow were 185.8 N, 154.0 N and 215.3 N, respectively.
Comparing all knots regardless of year of training, the SMC knot failed at significantly higher loads (237.2 ± 66.6 N) than the surgeon’s knot (203.7 ± 45.3 N, p = 0.049) and the Weston knot (193.5 ± 56.1 N, p = 0.013).
Regardless of level of training, 50% of the tied surgeon’s knots failed via suture breakage, while 26% of the Weston and 65% of the SMC knots failed via a suture breakage. When broken down by level of training, 46%, 25%, and 50% of the surgeon’s, Weston, and SMC knots, respectively, tied by PGYI residents failed via suture breakage. In comparison, 71%, 29%, and 71% of the surgeons, Weston, and SMC knots, respectively, tied by PGYV residents failed via suture breakage.