Purpose <p>To review Japan’s major contributions to hip joint preservation and reconstruction, spanning joint-preservingosteotomy, biomaterials innovation, and computer-assisted precision arthroplasty.</p> Methods <p>A narrative review was performed to summarize landmark clinical and scientific advances originating from Japan in the management of osteonecrosis of the femoral head (ONFH), developmental dysplasia of the hip (DDH), total hiparthroplasty (THA), bearing surface technology, and computer-assisted surgery.</p> Results <p>Japanese research has advanced the understanding and treatment of ONFH through nationwide epidemiological studies, development of classification systems, clarification of steroid-associated pathophysiology, and long-term validation of joint-preserving procedures, particularly transtrochanteric rotational osteotomy. In DDH, Japanese surgeons refined reconstructive osteotomies and established surgical strategies for complex primary and high-dislocation THA. Early clinical adoption of highly cross-linked polyethylene and advances in ceramic bearing technology improved implant longevity by reducing wear and osteolysis. Japan also pioneered CT-based navigation for both acetabular and femoral component placement and introduced the functional pelvic plane concept, shifting implant alignment from fixed safe zones toward individualized functional positioning that incorporates stem anteversion and spinopelvic dynamics. These innovations have subsequently expanded to robotic-assisted surgery and advanced three-dimensional reconstruction.</p> Conclusion <p>Japan has made substantial contributions to modern hip surgery, from biological joint preservation to precision arthroplasty. This integrated approach—emphasizing anatomical accuracy, biomechanical restoration, and long-term durability—continues to influence contemporary practice and provides a foundation for future advances in robotics, artificial intelligence, and personalized hip reconstruction.</p>