Biomechanical evaluation between the modified Mason-Allen stitch and the locked double-tie stitch on the infraspinatus of sheep.

OBJECTIVES: To evaluate and compare the in vitro biomechanical results from two stitches: the Mason-Allen stitch, as modified by Habermeyer; and the locked double-tie stitch developed at our service, on tendons of the infraspinatus muscle of sheep.

METHODS: Twenty tendons from the infraspinatus muscle of sheep were randomly divided into two groups: LDT, on which the locked double-tie stitch was performed; and MA, with the modified Mason-Allen stitch. The evaluation was performed in the mechanics laboratory, using a standard test machine with unidirectional traction, constant velocity of 20 mm per second and a 500 N load cell, without force cycling.

RESULTS: We observed that LDT was superior to MA, for the force needed to form spaces of both 5 mm (p = 0.01) and 10 mm (p = 0.002) and also for the maximum traction resistance (p = 0.003).

CONCLUSION: We confirmed our hypothesis that LDT stitches are superior to MA stitches from a biomechanical point of view. This is a further stitching option for surgeons, when fragile and poorly vascularized tendons need to be sutured, and it improves the quality of fixation without increasing the "strangulation" and, consequently, the ischemic area.