Design and biomechanical study of a novel double-leaf proximal humeral locking plate / 医用生物力学

ABSTRACT

Objective To design a novel double-leaf proximal humeral locking plate for fixing greater and lesser tuberosities in complex proximal humeral fractures,and evaluate its fixing stability by biomechanical tests.Methods Twelve fresh-frozen humerus specimens with intact rotator cuff were randomly divided into two groups (Group A and Group B) to establish the same greater and lesser tuberosities fracture models.Specimens in Group A were fixed with the double-leaf proximal humeral locking plate,while specimens in Group B were fixed with the proximal humeral internal locking system (PHILOS) and tension band suture,and a 3.5-mm cannulated screw was added to stabilize the lesser tuberosity.The tensile test on subscapularis,infraspinatus and teres,supraspi natus as well as the load-to-failure test on greater and lesser tuberosities were performed on specimens in two groups.Results For subscapularis tensile tests,displacements under 150 N tensile stretch and after fatigue test in Group A were both significantly smaller than those in Group B (P ＜ 0.05).For infraspinatus and teres tensile tests,there were no statistical differences between Group A and B in displacements under 150 N tensile stretch and after fatigue test (P ＞ 0.05).For supraspinatus tensile tests,there were no statistical differences between Group A and B in displacements under 90 N tensile stretch and after fatigue test (P ＞ 0.05).For load-to-failure tests on lesser tuberosity,the failure load in Group A was significantly greater than that in Group B (P ＜ 0.05),and the failure displacement in Group A was significantly smaller than that in Group B (P ＜ 0.05).For load-to-failure tests on greater tuberosity,there were no statistical differences between Group A and B in both the failure load and failure displacement (P ＞ 0.05).Conclusions Compared with the ordinary tension band suture plus cannulated screw for fixing lesser tuberosity,the novel double-leaf proximal humeral locking plate shows more obvious biomechanical stability,with the advantage of simultaneously fixing greater and lesser tuberosities.The research findings provide a new choice for the clinical treatment of complex proximal humeral fractures.