Fig. 6
From: Bent or broken: analysis of set screw fracture in the TFNa implant
Pictured from left to right: (1) Looking down at the lateral aspect of the lower half of a sectioned TFNa implant thru the proximal screw aperture. (2) The diameter of this sectioned proximal screw aperture is completely filled with insertion of the helical blade. (3) When the set screw is prematurely deployed, it acts as a mechanical block to the advancing helical blade. The blade is unable to advance any further than pictured without fracture of the locking prong. (4) Sectioned TFNa implant that has been displaced to show the direct contact of the helical blade against the locking prong when it has been deployed prior to blade/screw insertion