Biomechanical analysis of different locking locations in angle-stable intramedullary interlocking nail using a synthetic bone model with critical failure

Author(s)

Caio Afonso dos Santos Malta

• Document type: Master's Dissertation
• Press: Jaboticabal. 2020-06-29.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2020-02-20
• Advisor: Luís Gustavo Gosuen Gonçalves Dias Gosuen

Abstract

The present study aims to evaluate biomechanically (axial compression test) different positions and number of bolts locked to a new model of stable-angle intramedullary interlocking nail (ILN) in a simulation of complex diaphyseal fracture in synthetic bone models. The specimens were designed with end support for gripping on testing machines and were manufactured from polylactic acid (PLA) by 3D printer. The interlocking nail used in the experiment was developed with 6 holes (called 1 to 6 from proximal to distal) with internal threads, 3 at each end (proximal and distal). A specific apparatus (template stand) has been developed for full standardization and precise insertion of the interlocking nail and locking in the specimens. Twenty-eight samples were used, divided into four groups. In Group 1 (G1) the ILN was blocked in holes 1 and 6. In Group 2 (G2) the locking occurred in proximal holes 1 and 2, and distal holes 5 and 6. Group 3 (G3) fixed holes 2 and 3 (proximal segment) and 4 and 5 (distal segment). In Group 4 (G4), all 6 holes were locked by specific bolts. Axial compression tests were performed by a universal testing machine at a speed of 5 mm / minute. Data were evaluated between the four groups (G1, G2, G3 and G4), resulting in seven repetitions for each combination. The Shapiro-Wilk test was applied and concluded that the data presented normal distribution (p = 0.070). Among the average loads the highest value was recorded in G4 (9420.34N ± 4081.37N) followed by the groups G3 (9180.20N ± 1751.38N), G2 (8101.31N ± 2372.58N) and G1 (593.59N) ± 1300.79N). Despite the differences observed between the mean values none of them were statistically significant in the analysis of variance (ANOVA) (P = 0.074). Thus, it can be concluded that in the compressive axial load support there is no difference as to the number of bolts per fragment or in relation to the fracture distance that they are positioned. However, these results should be associated with biomechanical tests that evaluate flexural and torsional loads. (AU)

• FAPESP's process: 18/03382-5 - Biomechanical analysis of different locations of locking in intramedullary nail using test bodies with critical failure
• Grantee: Caio Afonso dos Santos Malta
• Support Opportunities: Scholarships in Brazil - Master