For posterior and posterolateral hip replacement incisions, which motion is NOT restricted?

• A. Hip flexion > 90 degrees
• B. Hip extension
• C. Adduction past midline
• D. External rotation

Answer: (D)

After a posterior or posterolateral hip replacement, precautions are designed to prevent dislocation by protecting the posterior tissues. Movements that place the femoral head into the posterior capsule—hip flexion past about 90 degrees, adduction across the midline, and internal rotation—are restricted to reduce this risk. External rotation does not load the posterior capsule in a way that increases dislocation risk, so it is not restricted and is often permitted. In short, external rotation is the motion that remains unrestricted after these approaches.