[Compression of the femoral nerve by a secondarily dislocated fragment of the lesser trochanter following pertrochanteric fracture of the femur].

Pertrochanteric fractures of the femur are often associated with avulsion of the lesser trochanter. The most commonly applied techniques of osteosynthesis (proximal femur nailing; PFN/dynamic hip screw; DHS/gliding nail) do not involve repositioning or fixation of this fragment, which is dislocated as the result of traction from the iliopsoas muscle so that it is resting in the soft tissue. We report the case of a 70-year-old male patient with a pertrochanteric femur fracture with an initially undisplaced lesser trochanter fragment after a fall (AO classification 31-A2). PFN was performed on the day of the accident after closed reduction. Following an uneventful course, with increasing mobilisation the patient developed a compression syndrome of the femoral nerve with unbearable pain in the thigh. The cause was compression of the femoral nerve by a secondarily dislocated fragment of the lesser trochanter. After revision from a ventral approach with removal of the fragment the patient experienced total relief of the pain. No similar cases have so far been reported in the literature.