A Biomechanical Study For The Fixation Of Greater Tuberosity Fractures Of Humerus With Three Different Fixation Techniques

Objective：Through the biomechanical testing for the three different fixationtechniques used for the treatment of greater tuberosity fractures of the humerus, tocompares the stability, to found a biomechanics basis for a better fixator choose in theclinical application.Methods：In18fresh frozen proximal humeri, standardized fractures of the greatertuberosity were created. The specimens were randomly assigned to one of three operationtechniques: two cancellous screws, wire tension banding and locking plates. Theseconstructs were mechanically tested by applying an increasing force to the supraspinatustendon. Load to5mm displacement (load to5mm yield point, LtYP) and load to failure(maximum stretch strength) were measured in Newton (N). All states were analyzedusing SPSS17.0software.Results：For the load to5mm yield point：Locking plates(in our study only2casesreached to5mm) techniques(802N, SD30) showed significantly higher values than bothtwo cancellous screws and wire tension banding; Tension banding (548N, SD123)showed significantly higher values than two cancellous screws (394N, SD123) too. Loadto failure values were significantly higher for tension bandin（g908N, SD93）and lockingplates（979N, SD143） than cancellous screws（744N, SD112）, But there was nosignificant diferences between tension banding and two cancellous screws. For thefailure mode: with the two cancellous screws group, only one case failured due to thescrews pulled out, and the remaining five specimens showed humeral head fractures atscrew insertion plane; Regarding the tension banding group, all specimens resulted in a fracture of the surgical neck; In locking-plate group four specimens had surgical neckfracture, two other cases were failed due to the fracture of anatomical neck of humerus.Conclusion: This study determined that locking plate have obvious biomechanicalstability than two cancellous screws; Although there were no significantly Statisticaldifferences, when compared locking plates vs. tension banding technology in Load tofailure values. But locking plates provided the strongest fixation for isolated fractures ofthe greater tuberosity and because LtYP is the most important parameter for clinicalapplication, Locking plate provided a new and better choice for treatment of isolatedgreater tuberosity fractures of proximal humerus.