This study compared the stabilizing effect of 2 intertrochanteric
(IT) fracture fixation
devices in a cadaveric hemi-pelvis
Eleven pairs of cadaveric
osteopenic female hemi-pelves with intact hip joint and capsular ligaments were used. An unstable IT fracture
(OTA 31-A2) was created in each specimen and stabilized with a single lag screw device (Gamma 3) or an integrated dual screw (IDS) device (InterTAN). The hemi-pelves were inverted, coupled to a biaxial apparatus and subjected to 13.5 k cycles of loading (3 months) using controlled, oscillating pelvic rotation (0–90 degrees) plus cyclic axial femoral loading at a 2:1 body weight (BW) ratio. Femoral head rotation and varus collapse were monitored optoelectonically. For specimens surviving 3 months of loading, additional loading was performed in 0.25 × BW/250 cycle increments to a maximum of 4 × BW or failure.
Femoral head rotation with IDS fixation
was significantly less than the single lag screw construct after 3 months of simulated loading (P
= 0.016). Maximum femoral head rotation at the end of 4 × BW loading was 7× less for the IDS construct (P
= 0.006). Varus collapse was significantly less with the IDS construct over the entire loading cycle (P
In this worst-case model of an osteopenic, unstable, IT fracture
, the IDS construct, likely owing to its larger surface area, noncylindrical profile, and fracture
compression, provided significantly greater stability and resistance to femoral head rotation and varus collapse.