[False aneurysm and bleeding caused by a secondary dislocated lesser trochanter fragment].

A 92-year-old woman incurred an unstable pertrochanteric hip fracture with avulsion of the lesser trochanter (type 31-A2 according to the AO classification). The fracture was treated by gliding nail osteosynthesis, without fixing the minimally displaced lesser trochanter. No intra- or postoperative complications were detected. Suddenly, after 30 days, a swelling of the proximal femoral region, accompanied by signs of haemorrhage, occurred.CT-scans showed a false aneurysm of the deep femoral artery and a dorsal laceration of the artery proximal to the aneurysm. X-rays showed a further dislocation with rotation of the lesser trochanter fragment. Intraoperatively, the tip of the lesser trochanter fragment was identified to be responsible for the laceration of the artery. The false aneurysm was resected and the defect bridged by a vascular prosthesis while the fragment was removed. Follow-up showed no further complications. According to case reports from the literature, false aneurysms and laceration of the deep femoral artery caused by dislocated lesser trochanter fracture fragments are rare.