The spiral blade modification of the Dynamic
Hip Screw (DHS) was designed for superior biomechanical fixation
in the osteoporotic femoral head. Our objective was to compare clinical
outcomes and in particular the incidence of loss of fixation. In a series of 197 consecutive patients over the age of 50 years
treated with DHS-blades (blades) and 242 patients treated with conventional
DHS (screw) for AO/OTA 31.A1 or A2 intertrochanteric fractures were
identified from a prospectively compiled database in a level 1 trauma
centre. Using propensity score matching, two groups comprising 177
matched patients were compiled and radiological and clinical outcomes
compared. In each group there were 66 males and 111 females. Mean
age was 83.6 (54 to 100) for the conventional DHS group and 83.8
(52 to 101) for the blade group. Loss of fixation occurred in two blades and 13 DHSs. None of
the blades had observable migration while nine DHSs had gross migration
within the femoral head before the fracture healed. There were two
versus four implant cut-outs respectively and one side plate pull-out
in the DHS group. There was no significant difference in mortality
and eventual walking ability between the groups. Multiple logistic
regression suggested that poor reduction (odds ratio (OR) 11.49,
95% confidence intervals (CI) 1.45 to 90.9, p = 0.021) and fixation
by DHS (OR 15.85, 95%CI 2.50 to 100.3, p = 0.003) were independent
predictors of loss of fixation. The spiral blade design may decrease the risk of implant migration
in the femoral head but does not reduce the incidence of cut-out
and reoperation. Reduction of the fracture is of paramount importance
since poor reduction was an independent predictor for loss of fixation
regardless of the implant being used. Cite this article:
