MRI Can Detect “Invisible” Femoral Neck Fractures in Patients with Shaft Fractures
For more than 40 years, orthopaedic trauma surgeons have been interested in this fairly common fracture combination, which is often seen in polytrauma patients. We have long hypothesized that much of the energy that fractures the femoral shaft is dissipated, leaving many ipsilateral neck fractures nondisplaced and difficult to recognize on plain radiographs.
But the consequences of missing a femoral neck fracture can be devastating. For example, because the neck fracture pattern is often vertical (Pauwels type III), the risk of displacing the neck fracture during intramedullary nailing is very high. Achieving reduction and fixation of a displaced neck fracture near an intramedullary nail—either intraoperatively or postoperatively—is extremely challenging.
Because of these issues, some authors recommend a thin-cut CT series to identify nondisplaced ipsilateral neck fractures preoperatively, and this protocol has been shown to significantly reduce the delay in identifying such fractures. In the February 19, 2020 issue of The Journal, Rogers et al. from UTHealth in Houston show that even with thin-cut CT, the crack can be missed. These authors added to the protocol limited-sequence MRI that identifies these fractures with very high sensitivity and takes <10 minutes to perform.
In this study, among 39 acute, high-energy femoral shaft fractures, the authors identified 4 ipsilateral neck fractures with MRI that were not seen on CT. Despite exhibiting polytrauma, 89% of all indicated patients in this study were evaluated preoperatively with the limited-sequence MRI protocol, including those in traction and those treated initially with external fixation.
The findings from this study should prompt trauma surgeons practicing in high-volume centers to develop similar MRI protocols. It may also be possible to develop such protocols in lower-volume centers, but in those settings it is especially incumbent on the surgical team to recognize that this fracture combination occurs in a fairly high percentage of cases and to carefully scrutinize plain radiographs and consider thin-cut CT scanning of the ipsilateral hip. In addition, the potential for an ipsilateral nondisplaced femoral neck fracture should trigger increased use of fluoroscopy during intramedullary nailing of shaft fractures, so that concomitant neck fractures can be recognized and stabilized with screws before they become displaced.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Polytrauma Patients Face Cancer Risk from Imaging Radiation
Orthopaedic surgeons work with radiation in some capacity almost every day. We would struggle to provide quality patient care if it were not for the many benefits that radiographic images provide us. But the more we are exposed to something, the less we tend to think about it. For example, how often do we discuss the risks of radiation exposure with our patients—especially those who are exposed to a large amount of it after an acute traumatic injury?
The article by Howard et al. in the August 7, 2019 issue of JBJS strongly suggests that polytrauma patients need to better understand the risks associated with radiation exposure as they progress through treatment of their injuries. The authors evaluated the cumulative 12-month postinjury radiation exposure received by almost 2,400 trauma patients who had an Injury Severity Score of 16+ upon admission. Those patients received a median radiation dose (not counting fluoroscopy) of 18.46 mSv, and their mean radiation exposure was 30.45 mSv. These median-versus-mean data indicate that a small subset of patients received substantially more radiation than others, and in fact, 4.8% of the cohort was exposed to ≥100 mSv of radiation. To put these amounts in context, the average human in the UK (where this study was performed) is exposed to about 2 mSv of background radiation per year, and there is good evidence suggesting that carcinogenesis risk increases with acute radiation doses exceeding 50 mSv.
Based on mathematical models (actual occurrences of cancer were not tracked), the authors conclude that for these patients, the median risk of fatal carcinogenesis as a result of medical radiation following injury was 3.4%. In other terms, 85 of these patients would be expected to develop cancer as a result of medical imaging—which struck me as a startling estimate.
So what are we to do? In a Commentary accompanying this study, David A. Rubin, MD, FACR offers some practical suggestions for reducing unnecessary radiation exposure. I personally feel that because the radiation associated with CT scans and radiographs can be, quite literally, life-saving for patients who have sustained traumatic injuries, increasing the chance that patients develop cancer later in life in order to save their life now is a good risk-benefit proposition. But the findings from this study should make us think twice about which imaging tests we order, and they should encourage us to help patients better understand the risks involved.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Don’t Overlook Possible Osteoid Osteoma in Kids with Hip Pain
Orthopaedists are seeing an increasing number of active, young patients with hip pain. A study by May et al. in the March 20, 2019 issue of The Journal of Bone & Joint Surgery strongly suggests that osteoid osteoma (OO)—a small, benign tumor characterized by dense sclerotic bone tissue—should not be overlooked in the differential diagnosis when working up these patients.
The authors identified and reviewed the records of 50 children and adolescents (mean age of 12.4 years) at their tertiary-care pediatric center who had received a diagnosis of OO within or around the hip between 2003 and 2015. Nighttime hip and/or thigh pain (90%) and symptom relief with NSAIDs (88%) were common clinical findings.
Sclerosis/cortical thickening was visible in 58% of the radiographs. Perilesional edema and a radiolucent nidus was found on all 43 of the available CT scans, leading the authors to conclude that “CT scans provide definitive diagnosis” of OO.
Unfortunately, 46% of these patients initially received an alternative diagnosis, the most common of which was femoroacetabular impingement (FAI), and a delay in diagnosis of >6 months occurred in 43% of patients. The authors note that concerns regarding radiation exposure have led some clinicians to order MRI rather than CT when evaluating pediatric hip disorders, but this study found that identifying an OO nidus with MRI was not as accurate as doing so with CT.
Regarding treatment, among the 41 patients who ultimately underwent percutaneous radiofrequency ablation (RFA) to treat OO, 93% achieved complete post-RFA symptom resolution. Complications from RFA occurred in 7% of patients who underwent the procedure.
Using CT Data to Diagnose Osteoporosis
Osteoporosis is a “silent” disease, often becoming apparent only after a patient older than 50 sustains a low-energy fracture of the wrist, proximal humerus, or hip. Monitoring serum vitamin D levels and DEXA testing represent ideal screening methods to prevent these sentinel fragility fractures. In addition, through programs such as the AOA’s “Own the Bone” initiative, the orthopaedic community has taken a leadership role in diagnosing and treating osteoporosis after the disease presents as a fragility fracture. Own the Bone is active in all 50 states and, through local physician leadership, is identifying individuals who present with a fragility fracture so they can receive follow-up care that helps mitigate bone loss and prevent secondary fractures.
We still have a long way to go, however. Recent analyses show that only 30% of candidate patients (albeit up from 20%) are receiving this type of evidence-based care. The best-case scenario would be to identify at-risk men and women (osteoporosis does not affect women exclusively) before a potentially serious injury.
In the December 5, 2018 issue of The Journal, Anderson et al. present strong evidence that computed tomography (CT) can provide accurate data for diagnosing osteoporosis. CT is increasingly used (perhaps overused in some settings) across a spectrum of diagnostic investigations. The osseous-related data from these scans can be used to glean accurate information regarding a patient’s bone quality by analyzing the Hounsfield unit (HU) values of bone captured opportunistically by CT. HU data are routinely ignored, but the values correlate strongly with bone mineral density, and they could help us recommend preventive care to our patients before a fragility fracture occurs. (For example, a threshold of <135 HU for the L1 vertebral body indicates a risk for osteoporosis.)
Orthopaedists should discuss the possibility of asking their radiologist colleagues who read CT scans of older patients to routinely share that data. When indicated, we could promptly refer patients back to their primary care provider for discussion of pharmacological treatment and lifestyle changes proven to help prevent primary fragility fractures. There is little doubt that our patients are getting older. Reviewing CT data could help us dramatically improve preventive care and decrease the risk of first-time fragility fractures.
Click here for additional OrthoBuzz posts about fragility fractures.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Cord Compression Reflects Neurological Outcomes after Thoracolumbar Injuries
The association between spinal cord compression and functional deficits following cervical spine trauma has been well studied using both CT and MRI. However, until now, there was little data evaluating whether that same association is true for thoracic spine injuries. In the February 21, 2018 edition of The Journal, Skeers et al. identified the same correlations between canal compromise, cord compression, and functional outcome in the T1 to L1 region.
Using retrospective data, the authors showed that the severity of neurologic deficits was associated with the amount of maximal cord compression, as measured with advanced imaging. More specifically, their univariate analysis showed that cord compression >40% was associated with a tenfold greater likelihood of complete spinal cord injury compared to cord compression <40%. This study also found that MRI measures osseous canal compromise more accurately than CT, probably because it more clearly visualizes soft tissue changes related to the posterior longitudinal ligament, ligamentum flavum, and facet capsule.
A major issue with this study (and with almost all studies that evaluate spine trauma) is that these advanced imaging techniques are temporally static; even when they’re obtained relatively soon after injury, they cannot capture the position of vertebral body fragments and posterior structure deformities that existed upon impact. This shortcoming is probably more relevant for younger patients, who are more likely to experience higher-velocity trauma.
The population in the Skeers et al. study is skewed a bit toward older patients (mean age 34.8) with relatively severe spinal injuries (mean TLICS of 7.8 and mean cord compression of 40%). These factors may highlight the roles that lower bone density and decreased soft tissue elasticity play in the setting of high-energy spine trauma.
Although the data reflect some variability, this study should help spine surgeons counsel patients and their families following these tragic injuries. The more severe the initial cord compression in the thoracic spine, the more likely there is to be severe neurologic injury without improvement.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
JBJS Editor’s Choice—Nonunions of Foot/Ankle Fusions Matter
In the December 7, 2016 issue of JBJS, Krause et al. analyze data from a 2013 industry-sponsored RCT to investigate correlations between nonunions of hindfoot/ankle fusions indicated by early postoperative computed tomography (CT) and subsequent functional outcomes. Whether nonunion was assessed by independent readings of those CT scans at 24 weeks or by surgeon composite assessments at 52 weeks, patients with failed healing had lower AOFAS, SF-12, and Foot Function Index scores than those who showed osseous union.
This study suggests that a CT should be obtained from patients who are at least 6 months out from a surgical fusion and are not progressing in terms of activity-related pain and function. Depending on the specific CT findings, a repeat attempt at bone grafting, with the possible addition of bone-graft substitute and/or possible modification of internal fixation, may be warranted to forestall later clinical problems.
Krause et al. imply that trusting plain radiographs that show no indication of fusion failure is not acceptable when patient pain and function do not improve in a timely fashion. Conversely, they conclude that their findings do not support “the concept of an asymptomatic nonunion (i.e., imaging indicating nonunion but the patient doing well),” because nonunions identified early by CT eventually resulted in worse clinical outcomes. The authors also noted that obesity, smoking, and not working increased the risk of nonunion, corroborating findings from earlier studies.
While advanced imaging such as CT is not necessary in foot/ankle fusion patients who are improving in terms of function, pain, and swelling , this study stresses the importance of achieving union following these fusion procedures.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
JBJS JOPA Image Quiz: Golf-Related Wrist Injury
This month’s Image Quiz from the JBJS Journal of Orthopaedics for Physician Assistants (JOPA) highlights the case of a 34-year-old man who presented with a 1-month history of hand and wrist pain after driving his golf club into the ground during a swing. Anteroposterior (AP) and lateral radiographs of the wrist are shown, and findings from the physical exam are described.
The Image Quiz reviews the anatomy of the wrist, focusing on the symptoms and mechanisms of hamate injuries. The quiz question is: After standard AP and lateral radiographs, which imaging modality or view would be most helpful in arriving at a definitive diagnosis? Options for treating a fracture of the hook of the hamate are also discussed.
JBJS Webinar: Managing Complex Proximal Humeral Fractures
Proximal humeral fractures are the third most common occurring fracture in patients over the age of sixty-five years. These fractures are often difficult to accurately classify, and they can also be challenging to treat surgically.
On Tuesday, April 19, 2016 at 8:00 pm EDT, a complimentary webinar, hosted by The Journal of Bone & Joint Surgery, will present findings from two recent JBJS studies that explore the classification and treatment of complex proximal humeral fractures.
Milton Little, MD will examine whether 3D CT imaging helps orthopaedic surgeons classify proximal humeral fractures, and Derek J. Cuff, MD will analyze findings from a study that compared reverse total shoulder arthroplasty with hemiarthroplasty for treating these fractures in elderly patients.
Moderated by JBJS Deputy Editor Andrew Green, MD, the webinar will also feature commentaries on the study findings from shoulder experts Michael J. Gardner, MD and J. Michael Wiater, MD. The last 15 minutes of the webinar will be devoted to a live Q&A session.
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