Abstract

A 71-year-old man underwent posterior-approached total hip arthroplasty (THA), and an immediate anterior dislocation occurred after surgery. Lumbosacral radiography revealed an excessive pelvic incidence and significant spondylolisthesis. We changed the neck length from standard to +7 mm during the revision surgery, and the increased offset could improve stability. The anteversion of aceta-bulum cup and stem did not change because posterior dislocation was still a significant concern in posterior-approached THA. After the revision surgery, the patient recovered well, and no recurrent dislocation occurred after that. Lumbosacral radiographs must be obtained before THA surgery for evaluation. Increasing the offset is an effective method for improving THA stability in patients with abnormal pelvic incidence.