股関節全置換術における不安定性の予防と治療

Instability is a challenging complication and a significant revision cause in hip replacement surgery. The incidence of dislocation ranges from 0.5 to 10% in primary prostheses and can reach up to 30% in revision surgeries. The literature describes several risk factors, including surgeon-, patient-, and implant-related factors. Knowledge of these factors is essential to preventing and managing instability cases. Preventive treatment involves preoperative planning, adequate component positioning, normal hip biomechanics reestablishment, risk factor identification, and proper implant selection. Approximately two thirds of dislocation episodes are treatable with non-surgical treatment with closed reduction, education, and muscle strengthening. One third of the cases develop recurrent dislocations and require surgical intervention. Revision surgery should target the cause of instability. When necessary, consider special implants, such as dual-mobility acetabular components, polyethylene-based lipped acetabular liners, constrained acetabular inserts, or large-diameter prosthetic heads. Technological advances in robotic surgery and the understanding of the biomechanics of spinopelvic swing-related dislocation are promising current topics that may improve the prevention and treatment of instability.