Decreases in Pulmonary Artery Oxygen Saturation During Total Hip Arthroplasty

When the femoral component is being inserted during total hip arthroplasty, venous obstruction occurs because of twisting and kinking of the femoral vein. Relocation of the hip joint is associated with an acute reduction in pulmonary artery oxygen saturation (s_vO₂). To determine whether changes in leg positioning could influence femoral venous occlusion, 19 patients undergoing 1-stage bilateral total hip arthroplasty were studied using a randomized crossover study design of 2 leg positioning maneuvers. Keeping the thigh flexed and internally rotated throughout implantation of the femoral component (technique 1) was compared to bringing the leg into extension while maintaining internal rotation (technique 2) after insertion of the femoral component. After relocation of the hip joint, the reduction in s_vO₂ was significantly less with technique 2 than technique 1 (P < .0001).