Cortical Button Fixation

Abstract

Background: Patellar tendon ruptures require surgical repair to optimize outcomes, but no consensus exists regarding the ideal repair technique. Cortical button fixation is a secure method for tendon repair that has not been studied in patellar tendons. Hypothesis: Cortical button repair is biomechanically superior to the standard transpatellar repair and biomechanically equivalent to suture anchor repair. Study Design: Controlled laboratory study. Methods: Twenty-three fresh-frozen cadaveric knees were used to compare 3 techniques of patellar tendon repair after a simulated rupture at the inferior pole of the patella. Repairs were performed at 45° of flexion using a standard transpatellar suture repair (n = 7), polyetheretherketone (PEEK) suture anchor repair (n = 8), or cortical button repair (n = 8). All specimens were tested on a custom apparatus to simulate cyclic open kinetic chain quadriceps contraction from extension to 90o of flexion. Outcomes of gap formation up to 250 cycles, maximum load to failure, and mode of failure were evaluated. Results: Cortical button repair had significantly less gap formation than anchor repair after 1 cycle (P < .001) and 20 cycles (P < .01) and significantly less gap formation than suture repair from 1 to 250 cycles (P < .05). Cortical button repair sustained significantly higher loads to failure than anchor repair and suture repair (P < .001). All suture repairs failed through the suture. Anchor repairs failed at the suture-anchor eyelet interface (n = 4) or by anchor pullout (n = 3). Cortical button repairs either failed through the suture (n = 5), secondary failure of the patellar tendon (n = 2), or subsidence of the button through the anterior cortex of the patella (n = 1). Conclusion: Patellar tendon repair using cortical button fixation demonstrated mechanical advantages over suture repair and anchor repair in cadaveric specimens. Cortical button fixation showed less cyclic gap formation and withstood at least twice the load to failure of the construct. Clinical Relevance: The biomechanical superiority of cortical button fixation may impart clinical advantages in accelerating postoperative rehabilitation.