Use of a Krackow Suture Technique with PEEK Barrel Augmentation for Subscapularis Repair is Stronger Than Use of a Mason-Allen Suture Technique

Abstract

BackgroundIn total shoulder arthroplasty, the subscapularis tendon is routinely mobilized, either by tenotomy, peel, or lesser tuberosity osteotomy, to visualize the joint and allow proper implant positioning. Careful mobilization of the subscapularis is undertaken to achieve an anatomic tension-free repair. This cadaveric study tests the biomechanical differences of two repair techniques of the subscapularis peel compared to the classically described technique. We hypothesize that adaptation of this subscapularis peel technique using a custom-designed polyether-ether-ketone (PEEK) barrel in the bicipital groove may further stabilize suture repair of the subscapularis. MethodsTwenty paired cadaveric shoulder specimens underwent subscapularis peel and repair via transosseous suture fixation. The PEEK barrel used was a laboratory prototype designed for the study (Catalyst OrthoScience, Naples, FL, USA). Five specimens were repaired using a traditional Mason-Allen suture; their paired shoulders were repaired using the PEEK barrel and a Mason-Allen suture. Five specimens were repaired using the Krackow suture; their paired shoulders were repaired using the PEEK barrel and a Krackow suture. Mechanical testing was performed using a uni-axial materials testing system with primary outcome of gap displacement and secondary outcomes of maximum load to failure and method of failure. ResultsThe Krackow repair method with and without PEEK augmentation was significantly stiffer than the Mason-Allen repair method with and without PEEK augmentation (p<0.001 across all groups). Adding augmentation changed the strength of the Mason-Allen repair without achieving statistical significance (p=0.0925). Inter-group differences in cyclic displacement were not statistically significant. The Krackow repair methods had higher mean maximal load at failure than the Mason-Allen repairs of 534 ± 108 N and 266 ± 98 N, respectively (p<0.001). Maximum load at 5mm displacement was significantly different across groups (p=0.004). Methods of failure in the Mason-Allen technique groups included knot and tendon failure, and in the Krackow technique groups included suture failure and lesser tuberosity fracture. ConclusionRepairing the subscapularis with a Krackow suture is significantly stronger than a Mason-Allen repair in stiffness as well as load to failure. The results reported here compare a Krackow suture with a more common Mason-Allen suture configuration, and demonstrate the application of PEEK augmentation to subscapularis repair techniques. This study can guide surgeon selection of an ideal subscapularis repair technique for stemmed or stemless total shoulder arthroplasty.