Update in Hip Imaging

Welcome to this issue of Seminars in Musculoskeletal Radiology dedicated to evolving concepts and controversies in hip imaging. This is an exciting time in hip imaging with new emerging clinical diagnoses and evolving imaging techniques.

The hip is a complex joint with numerous etiologies for the painful hip.[1] Clinical evaluation can be difficult given the variations in clinical findings and the multitude of possible injuries and causes of pain. Recent advances in hip arthroscopy have served as a springboard to gain new knowledge and innovative treatments for hip maladies. Advances in hip imaging techniques have kept pace and aided in the diagnosis and treatment of hip pain. In this issue, 10 distinct topics are discussed by leading experts in the field that cover the known, evolving, and some of the controversies we all face in imaging the painful hip.

We begin this issue with Drs. Jesse, Petersen, Strickland, and Mei-Dan from the University of Colorado reviewing the osseous, soft tissue, and vascular components of the hip and the normal anatomical variants that may lead to some of the pitfalls in hip imaging. They also review the most common hip measurements requested of the musculoskeletal radiologist by clinicians. Drs. Thomas and Robinson from Leeds Teaching Hospital in the United Kingdom and Drs. Li and Agur from the University of Toronto review imaging of the acetabular labrum that still poses many diagnostic challenges. Drs. Petchprapa and Recht from NYU Langone Medical Center-Hospital for Joint Diseases discuss the imaging of chondral lesions of the hip. They review the normal structure and function of articular cartilage and both current and emerging imaging methods for assessing macroscopic, microscopic, and ultrastructural cartilage health. These newer cartilage mapping techniques include delayed gadolinium-enhanced MRI of cartilage, T2 mapping, T1 rho, sodium imaging, and diffusion tensor imaging.

Drs. Dietrich, Dora, and Pfirrmann from the Orthopedic University Hospital, Zurich, Switzerland, relay their expertise in imaging the postoperative femoroacetabular impingement (FAI) hip. The imaging protocol, complications, and causes for hip pain following surgical intervention are discussed. Drs. Blankenbaker and Tuite from the University of Wisconsin discuss recognized impingement syndromes around the hip other than FAI. These entities are important to recognize and be part of your search pattern. They include ischiofemoral impingement, anterior inferior iliac spine/subspine impingement, and iliopsoas impingement.

The condition known as snapping hip presents as an audible or palpable snapping that occurs around the hip during hip motion and can lead to painful hip. Drs. Lee and Rosas from the University of Wisconsin and Dr. Phancao from National Orthopedic Imaging Associates discuss both the common and uncommon causes for snapping hip along with advanced imaging techniques. They provide an image-guided diagnostic and therapeutic algorithm. Lateral lesions of the hip are reviewed by Drs. Pan and Bredella from Radiological Associate Medical Group of Santa Clara Valley and Massachusetts General Hospital.

Hip trauma is a common entity in daily practice. Drs. Stephenson and Davis from the University of Wisconsin review the imaging techniques and assessment of hip trauma. Imaging the patient with persistent hip symptoms following arthroplasty can be challenging. Drs. Fritz, Lurie, and Miller of the Hospital for Special Surgery review optimization of MR protocols with techniques for metal artifact reduction and illustrate the imaging appearances of these conditions. We end this issue with imaging the pediatric hip by Dr. Kara Gill of the University of Wisconsin. Dr. Gill reviews common abnormalities of the hip from infancy through adolescence.

I would like to thank the editors for the opportunity to serve as guest editor for this edition on hip imaging as well as to each of the authors for contributing their time and expertise to this outstanding issue. Finally, we hope you find each article useful and that they expand your knowledge in this rapidly evolving field.

• References

• 1 Kelly BT, Williams III RJ, Philippon MJ. Hip arthroscopy: current indications, treatment options, and management issues. Am J Sports Med 2003; 31 (6) 1020-1037