Biomechanical Evaluation of Patellar Tendon Repair Techniques: Comparison of Double Krackow Stitch with and without Cerclage Augmentation

The purpose of this study was to evaluate two different repair techniques for the primary repair of patellar tendon ruptures. Using a cadaveric model, we biomechanically compared a double Krackow stitch with, and without cerclage augmentation. The specimens were tested at loads comparable to those likely to be encountered during an early rehabilitation program (approximately 40 Newtons) and for maximal mechanical parameters. The force at failure of the augmented repairs was 329 ± 89 Newtons (N), while the non-augmented repairs failed at 278 ± 87 N. However, the force required to produce significant gapping at the repair site was not significantly different between both repair techniques. Additionally, there was no significant difference between the mean stiffness of the repairs in both groups within the loading range from 10-100N. However, as expected, at loads greater than 100 N the cerclage augmented repairs were significantly stiffer. Most notably, there was no gap formation in any of the constructs tested at forces (40 N) comparable to those seen during an early passive extension and active flexion program. These data suggest that it may be possible to achieve the benefits of an early rehabilitation program without augmentation of the repair, and thus avoid the potential complications arising from this additional material.