Analysis of behavior of three different configurations for suturing tuberosities in humerus fractures treated by proximal hemiarthroplasty

Objective: To evaluate experimentally the distance between fragments in cadaveric specimens in proximal fractures of the humerus in four parts. Material and Methods: The study was conducted in 5 synthetic humeruses that reproduced a proximal fracture in 4 parts. With a fixation system, the robot reproduced the movements for rehabilitation of the glenohumeral joint. The suture configurations (Ethibond (R)) were standard, Boileau and a suture taking advantage of the strength vector of the tendons forming the rotator cuff. The robot performed an abduction of 100 degrees with an internal rotation of 45 degrees and external rotation. All these tests were performed 6 times with 60 repetitions each. Displacement of the fragments caused by the simulation movements during rehabilitation The displacement produced was measured between the tuberosities and with the diaphysis. Results: Decreased displacement between the fragments with the band pressure technique was up to three times less than standard and two times less than Boileau for reconstruction without damage to the cuff. In cases in which the rotator cuff was damaged, this difference was maintained. Conclusion: It is possible to improve the sutures currently used for fixing bone fragments in proximal humerus fractures treated with hemiarthroplasties, using strength vectors as guide for the direction of the tension bands.