Biomecânica de quatro técnicas de fixação da fratura em quatro partes da cabeça umeral

Abstract

OBJECTIVE: To carry out a biomechanical study of four techniques for fixation of four-part humeral head fractures. METHODS: The fracture was reproduced in 40 plastic humeri, divided into groups of ten according to the fixation technique, each one employing different fixation resources, in different configurations. The humeral models were mounted on an aluminum scapula, with leather straps simulating the rotator cuff tendons, and submitted to bending and torsion tests in a universal testing machine, using relative stiffness as an evaluation parameter. Assemblies with intact humeri were analyzed for comparison. RESULTS: The biomechanical behavior of the fixation techniques varied within a wide range, where the assemblies including the DCP plate and the 4.5mm diameter screws were significantly more rigid than the assemblies with the Kirschner wires and the 3.5mm diameter screws. CONCLUSION: The four fixation techniques were able to bear loads compatible with the physiological demand, but those with higher relative stiffness should be preferred for clinical application. Laboratory investigation .

Posterior four-part fracture-dislocations of the proximal humerus: clinical and functional evaluation of osteosynthesis treatment

“… 4 However, various other methods of osteosynthesis are also capable of providing stability and allowing early mobility. 20 Different osteosynthesis methods provide different degrees of stability, but show similar functional clinical results. 21 …”

Biomechanical analysis of plate systems for proximal humerus fractures: a systematic literature review

“…Tests for performance of multiple plates under same conditions, like Lever et al [ 63 ], can be achieved by using a large sample size and by performing multiple pairwise comparisons. As far as the fracture models are concerned, most of in vitro studies cover the common two- and three-part fractures, with a few studies even introducing four-part fractures [ 72 , 73 ]. However, the fracture patterns often varied and were according to different classification systems.…”

“…Overall, synthetic humeri were assessed in ten studies [ 41 , 47 , 55 , 59 , 62 , 66 , 70 – 73 ] while others tested human cadaveric humeri. Only two studies involved four-part fractures [ 72 , 73 ], both of which belonged to humerus-tendon category.…”

Biomechanical behavior of three types of fixation in the two-part proximal humerus fracture without medial cortical support

“…Stiffness and hardness are the two main structural properties which have been reported for artificial as well as cadaver humeri [19]. Studies using composite plastic models have demonstrated greater homogeneity, with lower standard deviation for stiffness and values within the limits of cadaver studies [20,21]. The same was seen in this present study, when the five intact specimens (group O) were tested identically to the other experimental groups and demonstrated homogeneous mechanical behavior among the specimens in terms of stiffness.…”