Periosteum-enhanced triple-pass Krackow stitch provides higher ultimate load than conventional Krackow methods in a bovine patellar tendon model: a controlled biomechanical study

In all-inside anterior cruciate ligament (ACL) reconstruction, grafts with free tendon ends require bilateral suturing to suspensory fixation devices during preparation. Despite prior descriptions of periosteal augmentation techniques and biomechanical analyses of different suture configurations, no study has specifically examined the biomechanical properties of a periosteum-augmented graft sutured with the Krackow technique. To address the uncertainty regarding the biomechanical superiority of suture configurations, three graft preparation techniques were biomechanically compared.

Bovine patellar tendons were mounted with the patellar end secured in the upper grip and the free tibial end fixed in the lower grip after preparation with one of three suture configurations: a periosteum-augmented triple-pass Krackow stitch (Group 1), a standard triple-pass Krackow stitch (Group 2), or a quintuple-pass Krackow stitch (Group 3). Each configuration comprised 10 specimens. All constructs were subjected to a cyclic loading protocol followed by monotonic axial load-to-failure testing, consisting of a 5 N preload, 500 loading cycles between 50 and 200 N at 1 Hz, and final load-to-failure testing performed at a constant failure displacement rate of 20 mm/min. Outcome variables were first cycle elongation, last cycle elongation, cyclic elongation, failure displacement, ultimate load to failure, and stiffness. Groups were compared using the Kruskal–Wallis test, with Dunn’s test and Bonferroni adjustment for post hoc pairwise comparisons; statistical significance was set at α = 0.05.

A significant group effect was found for the ultimate load to failure. Dunn–Bonferroni post hoc analysis indicated that Group 1 was superior to Group 2 (p_adj = 0.004) and Group 3 (p_adj = 0.001), with no difference between Groups 2 and 3 (p_adj = 1.000). No differences were found for first-cycle elongation, last-cycle elongation, cyclic elongation, failure displacement, and stiffness.

Within the limits of this time-zero bovine patellar tendon model, periosteum-augmented triple-pass Krackow suturing provided the most favorable ultimate load profile, whereas increasing the number of Krackow passes alone did not provide a measurable biomechanical advantage.