Publication:

A biomechanical comparison of two cephalomedullary nails; one using a single lag screw with antirotator blade and a nail using two lag screws for unstable intertrochanteric fractures

Background Implant choice for fixation of intertrochanteric fractures remains controversial despite being one of the most commonly performed operations. Although use of sliding hip screws is still considered a gold standard in treatment of these fractures, there is a wide tendency in using cephalomedullary nails because of their biomechanical superiority over sliding hip screws. This trial was initiated in order to compare the biomechanical properties of two different cephalomedullary nails, aPFN and the PROFIN under axial loading, based on the questions that can a single lag screw with an antirotator blade render better rotational stability? Is there a difference between one lag screw or two lag screws with respect to superior migration or cut-out of the screws? And do different nail designs cause different types of failure and what are the pros and cons of classical and new designs from the view point of biomechanical aspects?

Methods Ten pairs of third generation synthetic bone models simulating unstable intertrochanteric fracture were used for biomechanical testing.

Results No posterior displacement of screws was recorded in both groups suggesting rotational unstability.  There was not a significant difference between forces values loaded at the time of failure.

Conclusions Although there was no statistically significant difference between compressive strengths at the time of failure, aPFN may provide equal rigid fixation with less possible cut-out which may have an important consequences in real clinical applications.