Direct anterior approach (DAA) in supine position is one of the successful minimally invasive surgery (MIS) approaches, but it may need special traction table and stem selection is limited. DAA in lateral position is easier, and full porous cylindrical stem is easily inserted in this approach. The purpose of this presentation is to report this technique and result. 55 patients with osteoarthrosis (Crowe group1 to 3) were undergone THA with DAA in lateral position and followed for a minimum of 7months. Approach and cup settlement is the same as usual DAA in supine position. After liner placement, proximal femur is pushed up anterolaterally with the hip hyperextension, external rotation and adduction, which make excellent view of femoral neck cut surface. Because the leg is shortened, neurovascular relaxation is achieved. PCL retractor of TKA instrument is used to keep tensor fascia femoris muscle laterally over greater trochanter. No other special instrument is needed in stem insertion. Hip scores improved from 37.8 preoperatively to 87.8 postoperatively. Mean incision length was 9cm and mean operation time was 85minutes including routine intra-operative X-ray check. Neither auto blood donation nor cell saver was used. Blood transfusion was not needed. Stem position with over 2 degree varus were in 5 cases (9%) and over 2 degree valgus were in 3 cases (5%). There were no dislocation, loosening, infection, or femoral nerve injury.

In supine position, hip motion in sagittal plane has limitation. DAA in lateral position afford more extension with easily controlled external rotation and adduction which is the key to insert stem easily. DAA in lateral position is easy and tolerable MIS.