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What imaging is best to diagnose the source of hip-spine pathology symptoms?
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Standing, sitting lateral radiographs
There has been recent interest in joint arthroplasty in terms of how spinal motion might influence component position in patients undergoing total hip arthroplasty. In fact, recent studies have shown an increased risk of dislocation in patients with prior spinal fusions. The risk increases with the more levels fused or if the fusion extends to the sacrum. The fusion leads to a stiff spine, and patients are unable to go through the normal pelvic motion that occurs when going from a standing to a sitting position or vice versa, and, as a result, may increase their risk of THA dislocation. This research has prompted a number of surgeons to recommend that patients with underlying spinal pathology, such as lumbar stenosis or lumbar spondylosis, or previous spine surgery obtain certain imaging prior to THA to assess pelvic motion to determine their potential risk of postoperative instability. The most commonly used imaging is a standing and a sitting lateral of the pelvis and spine. This could be done with standard radiographic techniques or with advanced 2-D or 3-D imaging techniques, such as those available with EOS Imaging equipment. Additional information may be gotten by having the patient obtain a third radiograph that is done while the patient is leaning forward. Finally, some companies offer patient-specific planning for THA with information obtained from CT.
- References:
- Australian Orthopaedic Association National Joint Replacement Registry Annual Report. Available at: https://aoanjrr.sahmri.com/annual-reports-2018. Accessed May 20, 2019.
- National Joint Registry for England, Wales, Northern Ireland and the Isle of Man 15th Annual Report. Available at: www.hqip.org.uk/resource/national-joint-registry-15th-annual-report-2018/. Accessed May 20, 2019.
- For more Information:
- Rafael J. Sierra, MD, is an orthopedic surgeon and professor of orthopedic surgery at the Mayo Clinic College of Medicine and Science in Rochester, Minnesota.
Disclosure: Sierra reports he receives IP royalties from Link Orthopaedics and Zimmer Biomet, is a paid consultant for Link Orthopaedics and OrthoAlign, has stock or stock options in OrthoAlign and receives research support from Zimmer Biomet.
Added imaging after negative radiographs
Choosing the best imaging study to diagnose the source of hip and spine symptoms is greatly dependent upon the clinical scenario, which creates a complex topic to attempt to cover briefly.
Essentially, when hip pathology is suspected and initial radiographs are negative, MRI provides superior sensitivity to osseous processes that can be occult radiographically, including sacral and femoral insufficiency fractures, avascular necrosis and marrow-replacing lesions, including myeloma and metastatic disease. MRI’s ability for soft tissue characterization also offers a distinct advantage over other modalities in identifying myotendinous injuries and soft tissues masses, as well as intra-articular pathologies, such as labral tears, cartilage injuries and capsular abnormalities.
Evaluation of the spine is typically performed in the setting of back pain, radiculopathy or myelopathic symptoms. In high-mechanism trauma, the spine is evaluated concurrently with dedicated spinal reformations derived from CT evaluation of the chest, abdomen and pelvis. With chronic pain in patients older than 40 years, radiographs are useful in the initial evaluation of the osseous structures, and often can identify compression fractures, degenerative disc and facet disease, as well as pathologic fractures from metastases and myeloma. CT and MRI are more sensitive in evaluating each of these entities and can delineate neuroforaminal and spinal canal involvement. The use of MRI is ideal in children given the lack of ionizing radiation and is ideal for assessing pars interarticularis defects, as it is able to delineate key associated fibrocartilaginous masses and osseous traction spurs, which can further contribute to nerve root impingement.
- Reference:
- Major NM, et al. American Journal of Roentgenology. 1999;doi:10.2214/ajr.173.3.10470901.
- For more Information:
- Nancy M. Major, MD, is a professor of radiology and orthopedics at University of Colorado School of Medicine in Aurora, Colorado.
- James Korf, MD, is a radiology resident at University of Colorado School of Medicine in Aurora, Colorado.
Disclosures: Major and Korf report no relevant financial disclosures.