Trauma Femoral Head Fractures M. F. Swiontkowski Introduction The first recognition of femoral head fracture as a separate entity was published in 1869 by Birkett.’ From the outset. it was recognised that these were high energy injuries. It is generally agreed upon that the mechanism of injury is an axial load projected through the thigh, and directed posteriorly.’ If the femoral shaft does not fracture, a hip injury will result, if sufficient force is present. If the thigh is abducted, a femoral neck fracture may result; if neutral or adducted. a posterior hip dislocation with or without an associated femoral head or posterior wall acetabular fracture will occur. This mechanism explains the increasing incidence associated with automobile ac- cidents with loading of the thigh through the dash- board. : The final results of fracture healing, fragment resorption and/or femoral head necrosis are deter- mined by the traumatic effect of the hip dislocation on the arterial supply of the femoral head (Fig. 1). The head is supplied by three terminal arterial sources.3 These are the artery of the ligamenturn teres from the obturator system, a terminal branch of the lateral femoral circumflex artery, and the terminal branch of the medial femoral circumflex artery, the lateral epiphyseal artery. This vessel is the critical source of the majority of the weight bearing portion of the femoral head. In 907; of hip dislocations associated with femoral head fracture, the direction is posterior. With this injury. the medial femoral circumflex artery is stretched, and the lateral epiphyseal artery may be occluded due to pressure from the edge of the disrupted _________ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Marc F. Swiontkowski MD, Associate professor and Vice Chairman. chief of Orthopaedic Traumatology. Department of Orthopaedics, HarborvIew Medical Center, 325 Ninth zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Avenue, ?A 48, Seattle. Washington 98 104. USA x Anterior Posterior Fig. 1 -The blood supply to the adult proximal femur posterior hip capsule or acetabular labrum.s The anterior inferior femoral head fragment, which has been sheared off by the posterior wall of the acetabu- lum, generally remains within the acetabulum attached to the ligamenturn teres. This description relates to head fragments of significant size. When the fragment is inferior to the fovea, it may be free within the acetabulum. In larger fragments that traverse the supra-fovea1 region, the plane of the fracture most likely disrupts the osseous branches of the lateral femoral circumflex artery. The tension and/or occlu- sive pressure on the lateral epiphyseal artery makes prompt reduction of the femoral head within the acetabulum critical. It has been pointed out that the associated incidence of avascular necrosis of the femoral head increases with the number of hours that the hip remains dislocated.’ These concepts most certainly apply to the femoral head when there is an associated femoral head fracture.6.7 The maintenance of an optimal femoral head- acetabular contact needs there to be an entire femoral head. Accurate reduction of femoral head fragments that involve the articular cartilage is necessary to