Biomechanical Analysis of the Pectoralis Major Tendon and Comparison of Techniques for Tendo-osseous Repair
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The pectoralis major is a powerful adductor and internal rotator of the arm.7,10 Rupture of the pectoralis major is a relatively rare occurrence, with the majority of these cases occurring in athletes (in particular, weight lifters) and heavy laborers.10 While low-demand patients may have no difficulty with activities of daily life after nonoperative treatment, the inability to attain full strength without surgical repair necessitates operative treatment for the majority of athletes and laborers. There are only a number of small case series describing techniques and outcomes of pectoralis major repair. A recent meta-analysis reported excellent results in 88% of patients treated operatively. However, results of individual small case series vary from 46% to 100% excellent results. Despite a multitude of described repair techniques, there is no definitive gold-standard surgical procedure to repair the pectoralis major.
The principles of pectoralis major repair are the same regardless of the technique chosen. The goal is to utilize sutures to obtain an anatomic reduction of the tendon foot-print while avoiding injury to the adjacent long head of the biceps. A number of methods have been described to reattach the avulsed tendon to its normal humeral insertion. The majority of techniques involve suture repair using either transosseous tunnels and bone troughs or, more recently, suture anchors. In the largest series of surgical repairs (n = 33), Aarimaa found no difference between those treated with suture anchors and those with transosseous suture repairs. Additionally, a recent biomechanical study by Hart found no statistically significant difference in ultimate failure load and stiffness between suture anchors and transosseous sutures for pectoralis repair.
Our current methods of repair involve either a transosseous repair with 6 sutures through four 2.0-mm bone tunnels, a suture anchor repair utilizing 3 double-loaded 5.0- to 6.0-mm suture anchors, or an endosteal Pec Button (Arthrex, Naples, Florida) repair utilizing 3 double-loaded buttons. The biomechanical properties of using an endosteal Pec Button for pectoralis major repair have not been examined. Additionally, the biomechanical properties and strength of the native intact pectoralis have never been described. It is unknown how well these 3 repair techniques are able to restore the native properties of the intact pectoralis.
The goal of the current investigation is to critically evaluate the biomechanical profiles of these 3 repairs and com- pare the results with those of the native pectoralis to make evidence-based treatment recommendations for pectoralis major repair. Our hypothesis is that all repairs will have lower initial biomechanical profiles compared with the native attachment and that transosseous sutures will demonstrate improved initial biomechanical performance com- pared with anchors or buttons.