One-stage bilateral, muscle-preserving, calcar-guided implantation technique through the modified minimally invasive anterolateral approach in supine position. Bilateral primary/secondary osteoarthritis of the hip; bilateral femoral head necrosis; ASA I-III. ASA IV; severe osteoporosis, other factors jeopardizing stable anchorage of cementless, calcar-guided short-stem; infection. Supine position. Skin incision. Opening of fascia; blunt dissection, pushing gluteal muscles dorsally with the index finger. Capsulectomy. Individual osteotomy according to preoperative plan to determine short-stem position. Remove femoral head. Prepare acetabulum. Position cup. Femoral preparation with the curved opening awl. Spare greater trochanter and gluteal muscles. Insert trial rasps in ascending sizes with "round-the-corner" technique. Select offset version, then trial reposition with intraoperative radiograph and implantation of the definitive implant. Wound closure. Consultation with the anesthesiologist to confirm a stable patient. Same procedure on contralateral hip. Mobilization on day 1 with immediate full weight bearing. Remove wound drains and urinary catheter (only female patients) on day 2. Intensive protocol of physiotherapy and rehabilitation. Thrombosis prophylaxis. Rehabilitation from day 7. Almost 500 patients have undergone surgery since 2010. First consecutive 54 patients (108 hips) prospectively evaluated. After 2 years, Harris Hip Score was 98.8; satisfaction on visual analogue scale was 9.9. Low peri- and postoperative complication rates; no implant revisions. The muscle-sparing approach and the special "round-the-corner" technique in one-stage bilateral procedure leads to rapid mobilization and rehabilitation with excellent early clinical results and high satisfaction rates.