Biomechanical Analysis of Four Suturing Techniques for Radial Meniscal Tears Demonstrated the Advantage of the Cross-Tie Grip Suture

OBJECTIVES: The “Tie Grip suture” was designed to fix radial meniscal tears more rigidly than simple conventional sutures. However, one shortcoming was residual gapping at the central margin of the tear. We modified the original method to address this point and named it the “Cross Tie Grip suture”. The purpose of this study was to perform biomechanical tests to compare suture strength and stability between four suturing techniques; the original “Tie Grip suture”, the “Cross Tie Grip suture” and two conventional suture methods, the double horizontal and cross sutures. It was hypothesized that the Cross Tie Grip suture will show the least displacement and resist the greatest maximum load. METHODS: Forty fresh-frozen porcine knees were dissected to acquire 80 menisci. 20 menisci were tested in each group: original Tie Grip, Cross Tie Grip, double horizontal, and cross suture groups. A radial tear was created from the central margin to 2 mm to the menisco-capsular junction at the middle third of the meniscal body, equidistance from the anterior and posterior horns. Suture configurations are shown in Figure 1. The sutured menisci were set in a custom clamp, with a metric ruler positioned parallel to the clamp to serve as a measurement scale. All menisci underwent preconditioning from 5 to 20 N for 300 cycles at 0.5 Hz. Subsequently, submaximal loading was performed for 500 cycles from 5 to 20 N at 1 Hz. The cycle was paused at cycles 0, 100, 250, and 500 for digital photographs to be taken under a 5 N load. An image processing software (ImageJ; US National Institutes of Health) was utilized to analyze the digital photographs for gap measurement. Load to failure testing was done at 5 mm/min and failure mode was recorded. An a priori power analysis based on preliminary experiments with statistical power of 80%, and significance set at .05, sample size required was at least 18 per group. The data was analyzed by one-way analysis of variance and Tukey-Kramer post hoc test. P-values <0.05 were considered statistically significant. RESULTS: Displacement after 500 submaximal cycles was significantly small in the Cross Tie Grip suture group (0.4 ± 0.3 mm) compared to the 3 other suture methods (Table 1). Displacement was, 0.9 ± 0.6 mm, 1.2 ± 0.7 mm, 1.4 ± 0.6 mm (P < .05) for Tie Grip, double horizontal, and cross suture groups, respectively. Maximum failure load was significantly greater in the Cross Tie Grip (154.9 ± 29.0N) and Tie Grip (145.2± 39.1N) groups compared to the double horizontal (81.2±19.9N) and cross suture (87.3±17.7N) groups (P < .05) (Table 1). Tissue failure was the most common mode of failure in all groups. CONCLUSIONS: The Cross Tie Grip suture showed greater resistance to displacement compared to the original method and both conventional methods, the double horizontal and cross sutures. In respect to maximum load, the Cross Tie Grip suture was equivalent to the original method. Both Tie Grip sutures showed greater maximum load compare to the other conventional sutures; double horizontal and cross.