Horizontal suture placement influences meniscal repair fixation strength

Purpose: This in vitro biomechanical study investigated the influence of horizontal suture placement distance from the medial meniscal lesion repair site on fixation characteristics during submaximal cyclic and load to failure test conditions. Methods: Eighteen cadaveric (20-45 years of age) medial menisci with intact joint capsules were harvested within 24-48 h after death and divided into two groups of 9 specimens each for biomechanical testing. A 2. 0-cm-long antero-posterior vertical longitudinal lesion was created with a #15 scalpel 2. 0-3. 0 mm from the outer edge of each meniscus. Menisci were repaired using #2-0 suture material with two horizontal suture loops placed either 1. 0 mm (Group 1) or 3. 0 mm (Group 2) from the lesion site. Following repair, the lesion was extended completely through the meniscal horns so that no tissue secured the repair, only the two horizontal suture loops representing a "worst-case" testing scenario. Following repair, specimens were placed in a servo hydraulic device using a pair of 1. 2-mm-diameter steel wire loops and underwent submaximal cyclic loading between 5 and 50 N (1 Hz) for 500 cycles prior to load to failure testing (5 mm/min crosshead speed, 20 Hz data collection). An alpha level of P < 0. 05 was selected to indicate statistical significance. Results: Five of nine (55. 6 %) Group 1 specimens did not complete submaximal cyclic testing. All Group 2 specimens completed submaximal cyclic testing (Fisher's exact test P = 0. 029). Statistically significant mean group differences were not observed for displacement during submaximal cyclic loading (Group 1 = 5. 0 ± 1. 5 mm and Group 2 = 5. 7 ± 1. 6 mm) or for construct stiffness during load to failure testing (Group 1 = 50. 1 ± 6. 3 N/mm and Group 2 = 52. 6 ± 11. 9 N/mm). Group 2 displayed greater mean load at failure (112. 1 ± 40. 8 N vs. 72. 7 ± 11. 2 N, P = 0. 02) and mean displacement at failure (11. 1 ± 2. 2 mm vs. 7. 6 ± 1. 4 mm, P = 0. 03) than Group 1. Conclusions: Horizontal sutures placed slightly farther away from the meniscus lesion displayed superior repair fixation than sutures placed closer to the lesion. The superior biomechanical meniscal repair fixation provided by capturing greater tissue volume may enable safe earlier participation in functional exercise activities. Studies are needed to verify these findings in vivo.