A visit to the orthopedic surgeon almost always involves imaging of some kind. A large part of the evaluation of a patient with musculoskeletal symptoms requires not only a thorough history and physical exam, but some type of view of the underlying bones, ligaments, tendons or other soft tissue. Imaging of the extremities has become such an integral part of orthopedics that it is featured in every test and certification exam taken by surgeons looking to complete their board certification. This article aims to detail some of the basic orthopedic imaging studies and the reasons for ordering them. As always, any questions you have about your specific situation or diagnosis should be directed to your orthopedic surgeon.
Common Types of Orthopedic Imaging
X-rays allow your orthopedic surgeon to evaluate the bones and joints for fractures, dislocations, or malalignment. X-rays can be used to evaluate the cartilage space between the joints to diagnose arthritis. Because they show representations of three-dimensional objects in two dimensions, several different views of the bone are required for proper visualization. Doctors specializing in total joint arthroplasty such as knee, hip or shoulder replacements often use X-rays to help template their surgeries and guide their choices of implants.
If an X-ray is a snapshot or Polaroid of the bones, a fluoroscope is more like a camcorder, with moving images that can be viewed immediately on a monitor in the operating room or office. Orthopedic surgeons use fluoroscopy during procedures and surgeries to provide a continuous image of the bone or joint they are working on. This allows real-time viewing of the area and helps guide the placement of implants, fracture reduction or medications. A radiology technician runs the fluoroscopy camera while the surgeon positions the body part in the appropriate position.
Computed Tomography, or CT scans, can provide highly detailed information by using multiple “thin-sliced” X-ray images that are reconstructed using a computer algorithm into a single cross-sectional picture. Orthopedic surgeons use CT scans to help detect fractures that are not visible on X-ray and give details regarding the healing progress of broken bones. CT scans can also provide images of the soft tissue structures around the bones, including muscles, tendons, and ligaments. For production of advanced images, contrast can be injected, either intravenously or directly into the joint that is being examined.
Magnetic resonance imaging, or MRI, uses strong magnets and the reaction of the body’s tissues to these magnets to produce highly detailed images of the human body. Orthopedic surgeons use MRIs to evaluate the soft tissues for common diagnoses such as meniscus tears, ligament ruptures, rotator cuff injuries, and intervertebral disc herniation. Unlike X-rays and CT scans, an MRI does not use radiation to produce its images. Recent advances in computer programming and focused magnetic fields even allow patients with metal implants such as joint replacements to get an MRI if needed. Given the highly detailed images and relative safety of an MRI, it is often tempting for a patient to believe that an MRI will be able to diagnose any injury and thus request that an MRI be ordered before the other studies are completed. However, an MRI can often produce images that are too detailed, showing normal wear and tear or standard anatomic variants as if they were the cause of the patient’s symptoms. For example, multiple research studies have shown that a large percentage of normal healthy volunteers will show evidence of disc herniation if an MRI of their spine is obtained. Without proper context, an MRI can lead to over-treatment of a condition or treatment of a diagnosis that is not the actual cause of the patient’s symptoms. Therefore, most orthopedic surgeons will want to obtain a detailed history and physical exam before ordering an MRI. This allows the physician to formulate a list of likely diagnoses, and use the imaging to confirm the diagnosis and plan for surgery if necessary.
The advances in imaging have allowed orthopedic surgeons to improve the care they provide to patients. Future directions for imaging and orthopedics include quicker, more detailed images that can be obtained with less radiation or risk to the patient. The choice of which imaging study to obtain is a discussion that should be held between the patient and their orthopedic surgeon.