End caps are intended to prevent nail migration
(push-out) in elastic stable intramedullary nailing. The aim of
this study was to investigate the force at failure with and without
end caps, and whether different insertion angles of nails and end caps
would alter that force at failure. Simulated oblique fractures of the diaphysis were created in
15 artificial paediatric femurs. Titanium Elastic Nails with end
caps were inserted at angles of 45°, 55° and 65° in five specimens
for each angle to create three study groups. Biomechanical testing
was performed with axial compression until failure. An identical
fracture was created in four small adult cadaveric femurs harvested
from two donors (both female, aged 81 and 85 years, height 149 cm and
156 cm, respectively). All femurs were tested without and subsequently
with end caps inserted at 45°. In the artificial femurs, maximum force was not significantly
different between the three groups (p = 0.613). Push-out force was
significantly higher in the cadaveric specimens with the use of
end caps by an up to sixfold load increase (830 N, standard deviation
(SD) 280 These results indicate that the nail and end cap insertion angle
can be varied within 20° without altering construct stability and
that the risk of elastic stable intramedullary nailing push–out
can be effectively reduced by the use of end caps. Cite this article:
