Advisory Committee Chair
Alan W Eberhardt
Advisory Committee Members
Brent A Ponce
Jack E Lemons
Document Type
Thesis
Date of Award
2008
Degree Name by School
Master of Science in Biomedical Engineering (MSBME) School of Engineering
Abstract
Locked plating is frequently used to treat proximal humerus fractures. However, varus collapse remains common. Anatomic reduction may decrease the frequency of varus collapse though no studies have evaluated this relation. Hence the first part of this study was to evaluate the role of calcar comminution and calcar fixation upon fixation stability. Eleven matched humeri with three-part fractures were fixed with proximal humeral locking plate. Six pairs had an additional 1-cm medial wedge removed to simulate calcar comminution. Within each matched humerus, one had calcar fixation with long screws while the other did not. The constructs were then loaded to failure. Load and energy to failure, stiffness and displacement at failure were measured. A multivariate regression analysis was performed to evaluate the effect on the measurands. The results showed that the non-comminuted specimens yielded 49% and 45% higher average load and energy to failure than comminuted specimens (p<0.05). Additionally, calcar fixation resulted in 22% and 27% higher load and energy values in comminuted and non-comminuted specimens respectively (p<0.05). The study suggested that calcar comminution critically destabilizes proximal humerus fractures while calcar fixation provides additional stability. The second part of the project evaluates the properties of the lasso-loop stitch compared to simple, mattress, Modified Mason-Allen (MMA) and Massive-Cuff (MAC) ii stitches that are used in rotator cuff repairs. Effect of three tissue penetrator geometries (clever hook, chia perc-passer and ideal suture passer) and tissue bite size (0.5-cm versus 1.0-cm) on suture strength was also evaluated. One-hundred and twenty four sheep infraspinatus tendon were used. Each graft was first cyclically loaded and then loaded to failure. Peak to peak displacement, cyclic elongation and load to failure were measured. Two-way analysis of variance was employed to compare the different properties. The results showed that the lasso-loop stitch had similar failure values to the mattress stitch (p=0.62). No significant differences were found in the average load to failure between the different tissue penetrators (p>0.05). Also, a 1.0-cm purchase had a significantly higher failure load than the 0.5-cm bite size (p<0.05). In this study, three variable parameter were examined with the aim of improving suture-tendon strength.
Recommended Citation
Raghava, Parthasarathy, "Biomechanical Evaluation Of Proximal Humerus Fracture Fixation And Rotator Cuff Repair" (2008). All ETDs from UAB. 3623.
https://digitalcommons.library.uab.edu/etd-collection/3623