Pullout strength of meniscal repair after cyclic loading: comparison of vertical, horizontal, and oblique suture techniques

This in vitro biomechanical study with cyclic loading compared the pullout strength of vertical, horizontal, and oblique sutures used for meniscal lesion repair. Following repair of vertical longitudinal lesions created in bovine medial menisci, three groups of seven specimens (vertical, horizontal, and oblique sutures) underwent cyclic loading in a randomized test order (5 mm/min, cycling between 5 and 50 N at 1 Hz for 100 cycles) prior to load to failure testing (5 mm/min). Displacement did not differ between groups during cyclic or load to failure testing. Construct stiffness during cyclic testing was superior for the oblique suture (6.9 +/- 1.5 N/mm, P = 0.007) and the vertical suture (6.4 +/- 7 N/mm, P = 0.03) groups compared to the horizontal suture group (4.4 +/- 0.52 N/mm). The oblique suture (171.9 +/- 25.9 N, P < 0.0001) and the vertical suture (145.9 +/- 32.3 N, P = 0.001) groups displayed superior load at failure compared to the horizontal suture group (88.8 +/- 8.2 N). Construct stiffness during load to failure testing did not differ between groups. Suture rupture was the failure mode for all specimens of the oblique suture group. Suture rupture was the failure mode for 57% (4/7) of the vertical suture group with the remaining specimens (3/7, 43%) failing from intact suture pullout through meniscal tissue. All horizontal suture group specimens failed by intact suture pulling through meniscal tissue. With comparable stiffness during cyclic testing, comparable load at failure as vertical sutures, and less evidence of intact suture pullout through the meniscus, an oblique suture technique may combine the beneficial characteristics of vertical (superior biomechanical strength) and horizontal (ease of application, longer sutures with a tendency to cover a larger meniscal tissue area) suture-repair techniques.