Elongation of simulated whipstitch post anterior cruciate ligament reconstruction tibial fixation after cyclic loading

Abstract

Whipstitch-post (WSP) tibial fixation is one of the most widely used and clinically successful methods of soft tissue graft fixation for anterior cruciate ligament reconstruction (ACLR). However, some consider the method prone to laxity. We hypothesized that WSP would have low elongation rates after experimental cyclic loading. Eight cadaveric human semitendinosus and gracilis (ST/Gr) tendons had whipstitches woven into their overlapped ends. The grafts were looped around a metal bar, pneumatically clamped, and cyclically loaded. The adjusted mean experimental graft elongation for the WSP was 1.13 mm with a maximum elongation of 1.64 mm and a standard deviation of 0.32. These values are equivalent to the lowest published cyclic loading tibial fixation elongation data. Whipstitch-post tibial ACLR fixation is biomechanically sound with among the lowest rates of elongation after laboratory cyclic loading.

Posterior laxity increases over time after PCL reconstruction

“…Numerous studies have indicated that this usually occurs within the first hours after surgery [1, 5, 28]. Inferior graft anchorage within the bone–screw interface or loosening of the tibial fixation devices have been studied extensively in ACL surgery [10, 16, 29, 39, 40]. Contrary to its anterior counterpart, there is a paucity regarding loss of fixation after PCL reconstruction.…”

Effect of suturing the femoral portion of a four-strand graft during an ACL reconstruction

“…Currently, the graft behavior is still not completely clear; additionally, a widely used procedure such as suturing the hamstring tendon graft in a whipstitch fashion could influence the strength, stiffness and elongation of a graft construct [12]. This could be assessed on the basis of several variables such as strength and size of the suture, quality of the tissue, and suturing technique [12, 21, 28, 32]. In addition, suturing the looped‐over part of the graft is commonly performed by orthopaedic surgeons in order to allow a more even tensioning and load sharing between all four limbs of the graft at the time of tibial fixation [23, 26].…”

The fixation strength of tibial PCL press-fit reconstructions

“…The strain rate used in this study (1 mm/s) has most commonly used in recent investigations [12, 14, 17, 25, 28, 40]. Various different numbers of cycles, recovery periods, and strain magnitudes have been used in order to determine the biomechanical properties of graft fixations [24, 33]. In our view, several thousand cycles would have biased the measurements obtained for SG, because tendon knots are affected more by dehydration than bone blocks.…”