Blood flow changes to the femoral head after acetabular fracture or dislocation in the acute injury and perioperative periods

Objectives: Acute blood flow to the femoral head has been postulated to be affected negatively by traumatic acetabular fracture or dislocation. To the best of our knowledge, a prospective study that has examined acute changes in blood flow to the femoral head with respect to the timing of reduction and the effect of open reduction and internal fixation after acetabular fra cture or dislocations has not been performed. Design and Setting: From June 1994 to February 1996, fifty-four consecutive patients with hip dislocations with or without fractures of the acetabulum were entered into this investigation. The patients were categorized into t hree groups: isolated dislocations, fractures or dislocations requiring ope n reduction and internal fixation, and isolated acetabular fractures withou t dislocation but requiring open reduction and internal fixation. Single-ph oton emission computed tomography (SPECT) scans were obtained after relocat ions and preoperatively and postoperatively after open reduction and intern al fixation of displaced acetabular fractures. Results: The median dislocation time for ail patients flow was 4.00 hours ( range 1 to 24 hours). SPECT scanning showed a low blood flow pattern in fiv e (9.25 percent) patients. A low blood flow pattern was seen in patients wi th early and late relocation times. Open reduction and internal fixation wa s not statistically associated with an avascular pattern of blood flow. For ty-two (78 percent) of our patients were available for follow-up, with an a verage of 24.3 months and a minimum of one year. There was one false-positi ve, one false-negative, and thirty-eight true-negative scans. Conclusions: A global loss of scintillation in the femoral head as determin ed by SPECT scanning occurs in some patients with hip dislocations and frac tures or dislocations of the acetabulum in the early injury period. Changes in blood flow occurred in patients with short (one hour) and long (twenty- four hours) dislocation times. However, the development of avascular necros is could not be predicted by early SPECT scanning. Until further multicente r studies are performed, SPECT scanning cannot be recommended on an acute o r routine basis to predict those patients who will develop avascular necros is. Operative approaches for open reduction of the hip and internal fixatio n of acetabular fractures do not appear to affect blood flow to The femoral head. Although a golden time to relocation cannot be fully established fro m this study, early relocation is advised to decrease the potential risk of vascular spasm, scarring, and subsequent avascular necrosis.