Can we predict femoral head vitality during surgical hip dislocation?

PURPOSE Surgical hip dislocation is commonly performed in orthopaedic surgery for several pathologies that often present risk of avascular necrosis (AVN) of femoral head. Observation of blood spilling out from a drill hole, performed in the head after dislocation, has been proposed as a predictive test for AVN. No data have been published about test reliability. Study's aim was to evaluate the correlation between 'bleeding sign' and AVN in surgical dislocation for elective disease and for acetabular fractures. METHODS All patients meeting the indication for surgical dislocation were included in this prospective study. Patients with follow-up shorter than 8 months were excluded. Intra-operative assessment of head vascularity was performed in 44 patients through the 'bleeding sign': a 2.0-mm drill hole carried out on the head during surgery. A positive bleeding test was considered an immediate appearance of active bleeding. Development of AVN was considered the main outcome. Necrosis group criteria were detection of type II, III or IV X-ray according to Ficat classification. RESULTS Forty-four patients with selected acetabular fractures, slipped capital femoral epiphysis and femoral head deformity were enrolled. Mean age was 25 years and mean follow-up was 36 months. Thirty-eight patients presented positive intra-operative bleeding sign and six demonstrated no bleeding. Sensitivity for the 'bleeding sign' was 97%, specificity was 83%, positive predictive value was 97%, negative predictive value was 83% and accuracy was 95% (P < 0.001). CONCLUSIONS Bleeding after head drilling is a reliable test for AVN in patients who undergo a surgical hip dislocation.