Imaging of total hip arthroplasty: part II - imaging of component dislocation, loosening, infection, and soft tissue injury.

Overview

Despite the remarkable success of total hip arthroplasty as treatment of arthritis of the hip, complications can still occur, and imaging plays a crucial role for both diagnosis and guiding management. Component dislocation in total hip arthroplasty is usually diagnosed on radiographs, but cross-sectional imaging is necessary to quantitatively assess component orientation which may have predisposed to the dislocation. The definitive sign of component loosening on radiography is progressive motion of the component, but CT will provide more osseous detail and recent studies have shown the role of MRI in assessing component loosening as well. Infection is a devastating complication for which early diagnosis is crucial. Radiographs are not sensitive for infection, but there are certain MRI features that can suggest infection, and ultrasound and fluoroscopy are useful for guiding arthrocenteses to diagnose infection. Tendon and neurovascular injuries can be a source of long-term disability after total hip arthroplasty, and radiological studies, particularly advanced cross-sectional imaging such as MRI and ultrasound, often play an important role in their diagnoses.