Finite Element Analysis of Mechanics about Different Fixations for Greater Tuberosity Fractures of the Humerus

Abstract

Isolated greater tuberosity (GT) fractures of the humerus are common The rates of incidence have been reported in 14% to 25% among proximal humeral fractures Either open surgeries or percutaneous techniques using screws or suture anchors are well accepted for the reduction and fixation of GT fractures Bone screws are the common tool generally described for fixation of GT fractures in both open and arthroscopic surgeries Previous studies suggested that surgeons should exercise caution using screw fixation for GT fractures in older and osteoporotic bones because the screw provides suboptimal fixation in osteopenia bone of the GT fragments and lead to further damage the fracture fragments In such scenarios the suture anchor fixations might be the superior options Using suture anchor repair techniques can provide a better outcome to the older or osteoporosis patients but these procedures might damage the rotator cuff because the medial anchor is inserted through an intact cuff attached to the greater tuberosity fragment Therefore our purpose was to investigate the strength of different fixation constructs using suture anchors or screws under different bone mineral densities (BMD) and which kind of suture anchor techniques had the maximum stress appeared on tendon To investigate the strength of different GT fracture fixation techniques a finite element GT fracture model was built It consisted of four different fixations: Two screw (TS) Suture-bridge (SB) Double-row (DR) and Single-row (SR) fixations All of these fixation conditions were provided a 370 N loading under different bone qualities at 0? abduction Resulting stresses at the supraspinatus tendon and comparisons of different fixation strength from different BMD were studied The definition of fixation strength was the migration of GT fragment relative to the humerous Among all of these groups the TS fixation strength was the weakest when the BMD was under 0 1 g/cm3 And the Double-row fixation had a superior strength in the entire suture groups Additionally the maximum von-Mises stress of DR technique was 57 68 MPa which is more than the other fixations under a 370 N loading at 0? abduction In our study we suggest that the suture anchor construct was the superior option when BMD is less than 0 1 g/cm3 Additionally Double-row fixation has some negative effects that would cause a large stress concentration at the medial row and damage the rotator cuff tendon

Date of Award	2014 Aug 28
Original language	English
Supervisor	Ming-Long Yeh (Supervisor)