Abstract
Unstable intertrochanteric fractures may be treated by several types of implants, most frequently by dynamic sliding hip screw or some form of intramedullary implant. Intramedullary implants began to be used in cases with an expectation of further improvement of osteosynthesis stability. A need to determine the advantages of single implants for selected types of fractures in randomized trials was defined. In addition to biomechanical principles, bone quality is considered, together with increasing possibilities in recent years of further improving density measurements, especially qCT with respect to local specificity. A series of 86 patients (24 men, 62 women, average age 77,6 years) was operated on from September 6, 2005 to June 30, 2009 for unstable intertrochanteric fracture (31 A2.1, A2.2, A2.3), either by DHS of PFN osteosynthesis after randomization. A CT examination of both hip joints in a predefined manner was performed before surgery. Using special software the relative density of the central spherical part of the femoral head 2 and 3 centimetres in diameter was determined. After fracture healing, the dynamization of the neck screw of both implants and the reduction of vertical distance between the tip of the neck screw and subchondral bone of the femoral head were determined. In addition to evaluation of osteosynthesis stability and osteosyntheis failure, clinical parameters such as surgical time, blood loss and length of hospital stay were compared between the two groups of patients. Survival of patients was evaluated with respect to April 21, 2010. In the patient series, 4 failures of DHS osteosynthesis (cut out) and 2 failures of PFN osteosynthesis (cut out) were noted. Sliding of the DHS was on average 11,9 mm, and was significantly higher in comparison to dynamization of the PFN neck screw, which was 6,9 mm (p=0,005). When comparing the vertical distance between the tip of the neck screw and subchondral bone of the femoral head immediately after surgery and after fracture healing the average reduction of the vertical distance was 1,6 mm in DHS osteosynthesis and 0,8 mm in PFN osteosynthesis. The difference was statistically significant (p=0,025). PFN seems to provide a more stable fixation, based on the measurements. The number of failed DHS osteosyntheses is higher in comparison to the number of failed PFN osteosyntheses but the difference is not statistically significant. The influence of femoral head density on osteosynthesis failure could not be determined due to a low number of failed osteosyntheses in both patient groups. At the same time, after statistical analysis, influence of the relative femoral head density on vertical distance reduction between the screw tip and femoral head subchondral bone in healed fractures was not proven. Statistically, average length of surgical time, length of hospital stay, mean blood loss and survival did not differ significantly between the two patient groups.
