Arthroplasties and Musculoskeletal Reconstruction

This issue of Seminars in Musculoskeletal Radiology (SMR) addresses current standards of practice and recent developments in joint arthroplasties, fracture fixation, and spinal instrumentation hardware. Numerous surgical implants are used in the upper and lower extremities and spine. It is of great importance for practicing radiologists to be able to recognize the normal imaging appearance of these devices and the imaging findings associated with their potential complications. This is critical for assessment of a postoperative orthopaedic patient.

Radiographs remain the mainstay in the evaluation of surgical hardware. Improved techniques in computed tomography (CT) and magnetic resonance (MR) imaging, such as metal artifact reduction, have allowed radiologists to diagnose hardware-related complications in much greater detail than before. Increasingly utilized, ultrasound (US) examination may contribute to the evaluation of the peri-hardware soft tissues, help with surgical planning, and guide percutaneous treatments. Due to the large number of images and pages needed to describe the normal radiologic appearances and possible complications of numerous orthopaedic devices discussed by several authors, four of eleven articles in this issue are published online only.

The article by Drs. Gaetke-Udager and Yablon reviews various fractures and hardware fixation options about the shoulder including the distal clavicle, proximal humerus, and glenoid. Three-dimensional CT has become increasingly useful in preoperative planning for many of these surgeries, especially for understanding glenoid morphology. Drs. Bartolotta, Daniels, Verret, and Fufa discuss the role of imaging for preoperative characterization and classification of fractures in the rest of the arm including elbow, forearm, wrist, and hand. For several surgical fixation options for these injuries, potential complications are also discussed.

The update on shoulder arthroplasty by Drs. Chen and Chen emphasizes how preoperative imaging assessment of rotator cuff and glenoid morphology has evolved in recent years. Humeral hemiarthroplasty, anatomical total arthroplasty, and total reverse arthroplasty and imaging appearances of their complications are reviewed. Radial head replacement, capitellar resurfacing, and total elbow arthroplasty are becoming increasingly performed. Indications along with pre- and postoperative imaging are discussed by Drs. Levin and Plotkin. There have been many notable recent developments in hand and wrist arthroplasty options, discussed by Drs. Petscavage-Thomas, Gustas-French, and Walker. The new surgical options, including first carpometacarpal arthroplasty and distal radioulnar joint prosthesis, will hopefully decrease pain and increase mobility for patients with debilitating hand/wrist arthritides, but their potential complications must be recognized in postoperative imaging.

Dr. Sanal and coauthors discuss commonly used classification systems of pelvic ring and femoral fractures and fracture dislocations, as well as imaging algorithms in preoperative evaluation of these injuries. They also discuss the normal imaging appearance of pelvic ring and femoral surgical hardware in postoperative patient follow-up and the imaging appearance associated with hardware complications. Similarly, Dr. Mar and coauthors provide a systematic update on radiologic evaluation of lower leg, ankle, and foot fracture fixation.

Drs. Deshmukh and Omar discuss imaging findings of different types of hip arthroplasty emphasizing recent advancement in metal reduction artifact techniques on CT and MR imaging including iterative metal artifact reduction (iMAR) techniques that were developed to decrease metal artifact on single-energy CT. Dual-energy CT, if available, can be used to decrease beam-hardening artifacts related to metal implants. Of importance is that in the clinical setting, iMAR reconstructions can be obtained after image acquisition. The decision to use dual-energy CT for metal artifact reduction is needed before image acquisition.

Dr. Mar and collaborators provide an update on imaging of the various types of knee arthroplasty that is currently the most commonly performed joint replacement surgery in the United States with an expected increase in frequency. Radiographs represent the mainstay imaging evaluation of knee arthroplasties with other imaging modalities including US, nuclear studies, CT, and MR imaging having the added value in their evaluation, mainly in the setting of suspected postoperative complications. Contrast-enhanced MR angiography, despite artifact from three-dimensional gradient-echo images, can show rare vascular complications such as pseudoaneurysm or arteriovenous fistula that can be treated with endovascular embolization.

With better understanding of ankle biomechanics and the biological effects of orthopaedic devices on ankle function, newer surgical techniques have led to significant improvements in the designs of total ankle arthroplasty (TAA). TAA in recent decades has been increasingly used for treatment of end-stage tibiotalar osteoarthritis. The article by Drs. Omar, Abboud, and Youngner provides an update on the normal radiographic appearances as well as the common complications seen with this procedure and discusses the added value of advanced imaging techniques.

In their update on imaging of the spinal fixation hardware, Dr. Winegar and coauthors discuss a myriad of instrumented spinal surgeries. Knowledge of normal imaging appearance of implanted spinal hardware along with the expected progression of normal postoperative osseous arthrodesis enables recognition of potential complications and helps facilitate appropriate clinical management.

As guest editors of this issue, we thank all of the authors for spending time to prepare excellent articles and sharing their knowledge and expertise with our readers. In addition, we would like to thank Dr. Laura Bancroft for the invitation to guest edit this issue and for providing guidance from concept to publication.