MRI may help identify femoral neck fractures not diagnosed by CT scan
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Use of rapid limited-sequence MRI in patients with femoral shaft fractures may help identify femoral neck fractures not diagnosed on thin-cut high-resolution CT without delaying definitive treatment, according to published results.
In September 2018, the McGovern Medical School at UTHealth Houston altered its imaging protocol for acute, high-energy femoral shaft fractures to include rapid limited-sequence MRI to evaluate for occult femoral neck fractures due to delayed diagnosis of femoral neck fractures despite thin-cut high-resolution CT. Upon presentation, Stephen J. Warner, MD, PhD, and colleagues collected standard radiographic imaging, as well as thin-cut high-resolution pelvic CT imaging of all patients with acute, high-energy femoral shaft fractures and blunt trauma. Researchers evaluated for occult femoral neck fractures with rapid limited-sequence MRI of the pelvis.
Of 37 patients with 39 acute, high-energy femoral shaft fractures resulting from blunt trauma, researchers found 25.6% had open femoral shaft fractures. Researchers detected ipsilateral femoral neck fractures on radiographs in 5.1% of femoral shaft fractures and no MRI was performed. Results showed no association between the remaining 37 femoral shaft fractures and a femoral neck fracture identified on CT imaging.
Researchers performed pelvic MRI on 89.2% of 37 patients to evaluate the ipsilateral femoral neck. Of the 33 patients evaluated, researchers diagnosed 12.1% with a femoral neck fracture not identified on thin-cut high-resolution CT or radiographic imaging.
“Our study suggests that implementation of the rapid limited-sequence MRI can improve our ability to diagnose femoral neck fractures in patients with high-energy, ipsilateral femoral shaft fractures,” Warner told Healio Orthopedics. “By optimizing our preoperative diagnosis of this injury, we can more effectively preoperatively plan, inform patients, focus physical therapy and enhance our patient care.” – by Casey Tingle
Disclosures: Warner reports he receives personal fees from Synthes. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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David J. Hak, MD, MBA, FAAOS
The recognized association of occult femoral neck fractures in patients sustaining high-energy femoral shaft fractures and the potential detrimental consequence of missing this injury, has led to various protocols to better identify the femoral neck fracture which may be nondisplaced and challenging to visualize. These protocols have included dedicated hip X-rays and CT scans. Despite these protocols, the authors show that it is still possible to miss an associated femoral neck injury in this patient population. Using a protocol that included MRI, the authors of this study found four previously unidentified femoral neck fractures in a cohort of 33 patients sustaining a high-energy femoral shaft fracture in which both plain radiographs and CT scans failed to identify the associated femoral neck fracture. This represents a 12% missed injury rate based on using the CT scan alone. We know that MRI is extremely sensitive in its ability to identify acute bony injury, and, in this study, MRI identified two fractures that were incomplete. While not all institutions may have the capability of obtaining a rapid limited-sequence MRI, the study’s protocol likely represents the most accurate method to identify an occult femoral neck fracture in this patient population.
Professor of orthopedic surgery
Sanford, Florida
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