Postoperative Rehabilitation Following Total Hip Arthroplasty in Achondroplasia: A Case Report Focused on Dislocation Prevention and Environmental Simulation

Individuals with achondroplasia (ACH), a skeletal dysplasia characterized by disproportionate short stature and joint laxity, often adopt greater hip flexion as a compensatory movement to navigate environments designed for individuals of average stature, such as when climbing relatively high standard steps or using standard-height furniture. This necessary adaptation, however, consequently increases the risk of dislocation following total hip arthroplasty (THA). This case report describes the postoperative rehabilitation course of a 68-year-old Japanese woman (height: 113.7 cm, weight: 31.8 kg, body mass index: 24.6 kg/m²) with ACH and coexisting osteoarthritis who underwent a right THA via the posterior approach. The patient's primary goal was to return to living on the second floor of her two-story house. Achieving this goal required her to learn how to negotiate stairs safely, with careful attention to minimizing dislocation risk, to ensure a safe discharge home. Early postoperative rehabilitation was specifically tailored to her short stature. It included transfer training with a footstool and gait training with a pediatric walker. A key part of the rehabilitation was early stair negotiation training, which used an adapted kneeling technique to prevent deep hip flexion. This technique simulated her home environment and was designed to reduce the risk of posterior dislocation. By postoperative day (POD) 7, the patient could walk independently with a T-cane. By POD 24, she had mastered stair negotiation, which allowed her to be discharged home. This case highlights the critical need for highly individualized rehabilitation plans for patients with ACH undergoing THA. Successful outcomes depend on careful consideration of the patient's specific body measurements (anthropometrics), their home environment, the early start of adapted movement training, and thorough education on how to prevent dislocation.