Pectoralis Major Repair: A Biomechanical Analysis of Modern Repair Configurations Versus Traditional Repair Configuration

Abstract

Background: Pectoralis major (PM) ruptures are increasingly common, and a variety of surgical techniques have been described. However, tested techniques have demonstrated diminished strength with inadequate restoration of the footprint and suture failure at relatively low loads. Purpose/Hypothesis: The purpose was to biomechanically compare PM transosseous suture repair (current gold standard) to modern PM repair techniques that use larger caliber sutures, suture tape, and unicortical button fixation (UBF). The null hypothesis was that there would be no mechanical difference between repair techniques and no difference in the amount of footprint restoration. Study Design: Controlled laboratory study. Methods: Twenty-four fresh-frozen cadaveric shoulders controlled for age and bone mineral density were randomized equally to 4 groups: (1) UBF, suture tape; (2) UBF, No. 5 suture, suture tape; (3) bone trough with No. 2 suture; and (4) native PM tendon group; all groups were tested to failure. The specimens were tested under cycling loads (10 N to 125 N) with a final load-to-failure test at 1 mm/s. Failure modes were classified by location and cause of rupture based on optical markers, while tendon footprint length was measured to determine amount of footprint restoration. Results: For fixation strength, the mean peak load was significantly greater in the native tendon (1816 ± 706 N) versus UBF/No. 5 suture/suture tape (794 ± 168 N), UBF/suture tape (502 ± 201 N), and bone trough (492 ± 151 N) ( P < .001 for all). UBF/No. 5 suture/suture tape featured the lowest displacement superiorly (1.09 ± 0.47 mm) and inferiorly (1.14 ± 0.39 mm) with a significant difference compared with bone trough. With regard to tendon footprint reapproximation, cortical button fixation best approximated native tendon footprint length versus bone trough. Conclusion: Based on peak failure load, the UBF/No. 5 suture/suture tape construct demonstrated 61% greater construct strength than a traditional bone trough technique. Moreover, displacement after cyclic loading was by far smallest in the UBF/No. 5 suture/suture tape construct. Therefore, repair constructs with larger caliber suture and suture tape provide a measurable improvement in construct strength versus traditional PM repair techniques in a biomechanical model and may be advantageous for repair. Clinical Relevance: Cortical button fixation with larger caliber suture and suture tape allows for a significantly better PM repair than more traditional techniques at the time of surgery, which may ultimately result in improved clinical outcomes if implemented in surgical practice.