Comparison of Pullout Strength of Resorbable Screws and Titanium Screws in Human Cadaveric Laryngeal Cartilage

Abstract

To compare the pullout strength of titanium screws and resorbable screws from human fresh-frozen cadaveric laryngeal cartilage. The importance of drill hole diameter, screw diameter, and whether the drill hole was tapped (resorbable screws only) was also determined. Prospective. Sixteen cartilage specimens were tested after debridement of connective tissue and perichondrium. Linear pullout strength of screws was measured using a load cell. Titanium and resorbable screw sizes of 1.5 and 2.0 mm were tested using drill hole diameters of 1.1 and 1.5 mm. For the resorbable-tapped group, screw diameters of 1.5 and 2.0 mm were tapped with 1.5 and 2.0 mm taps, respectively. All tested screws were 6 mm in length. We found a uniformly constant difference between the three screw types (P < .001). Post hoc analysis indicated a significant difference between the resorbable-untapped screw and both the resorbable-tapped screw and the titanium screw. We failed to find a significant difference, however, between the resorbable-tapped screw and the titanium screw. We also found a significant effect in regard to screw size (P = .0133), with post hoc analysis demonstrating the 1.1/1.5 mm combination to be inferior to the 1.1/2.0 and 1.5/2.0 mm combinations. There was no significant difference between the 1.1/2.0- and 1.5/2.0-mm combinations. Resorbable screws with untapped drill holes result in higher resistance to linear loads than both titanium screws and resorbable screws with tapped drill holes. The 1.1/2.0- and 1.5/2.0-mm drill/screw combinations are superior to the 1.1/1.5-mm combination when considering untapped resorbable screws.