Postoperative imaging of the hip

Abstract

To assess postoperative imaging of the hip joint regarding possible complications, it is indispensable to have in-depth knowledge of commonly used surgical techniques, access routes, and the implanted materials. While radiography is used to evaluate the position of foreign material and to rule out periprosthetic fractures that have occurred intraoperatively, follow-up examinations might show signs of material failure, aseptic loosening, prosthesis infections, or the occurrence of heterotopic ossifications. If radiographic findings are ambiguous, computed tomography (CT) may be used to clarify findings, whereas magnetic resonance imaging (MRI) is helpful to identify intra- and periarticular soft tissue pathologies such as surgery-associated cartilage and ligament damage, muscle insufficiency, or metallosis. To guide clinical decision making in common postoperative complications, various classification systems are available, e.g., for periprosthetic fractures, aseptic loosening, or heterotopic ossification. However, the differentiation between aseptic material loosening and septic endoprosthesis infection remains challenging if based on imaging alone. The assessment of postoperative hip imaging should be closely linked to the respective surgical technique and the implanted foreign material, whereby different probabilities of specific complications can be derived.