[Repetitive reoperation of the DHS failure: clinical and biomechanical analysis - a case report].

The author describes a rare case of repetitive reoperation of Dynamic Hip Screw failure due to the pull-out of the plate. An 86-year-old female patient suffered an injury - a pertrochanteric fracture of the left femur which was treated by DHS. After 14 weeks a new fall occurred and caused the DHS to fail - the plate pulled out and all cortical screws were broken. The first reoperation using a six-hole plate was performed. After a year and the patients new fall, a femoral fracture occurred in the area of the distal cortical screw underneath the plate. The DHS was removed, plate osteosynthesis of the femur was performed and the trochanteric fracture healed. No further complications were found, the patient died almost two years after the second reoperation. The biomechanical analysis of this case revealed a stress concentration close to the implant yield limit in the area of the distal cortical screw. Femoral neck screw placement was suitable with regard to the stress distribution. Key words: dynamic hip screw - proximal femoral fractures - osteosynthetic material breakage.