Tag Archive | stress fracture

Helpful Hint for Managing Femoral Neck Stress Fractures

Hip Effusion for OBuzzThe incidence of patients presenting with proximal thigh and groin pain is increasing along with increased interest in recreational athletic activity. When it is associated with a history of increased physical activity, this pain profile often prompts the ordering of a hip MRI if presenting radiographs are unremarkable. However, surgeons often find it difficult to make accurate prognoses and treatment recommendations when the MRI findings suggest a femoral neck stress fracture.

In the September 5, 2018 issue of The Journal, Steele et al. provide us with helpful hints for determining when to proceed with surgical stabilization of the femoral neck in this clinical scenario. Of the femoral neck stress fracture patients in this study who progressed to a surgical procedure, >85% had an effusion on the initial MRI, compared with only 26% of those whose condition resolved with nonoperative treatment. In statistical terms, those who had a hip effusion had an 8-fold increased risk of progression to surgery compared to those without a hip effusion. Meanwhile, the overall fracture-line percentage on the initial MRI turned out to be a poor metric for predicting progression.

Stabilization of a femoral neck stress fracture with percutaneous implants usually improves pain and predictably prevents displacement of the fracture and the attendant risk of nonunion and osteonecrosis of the femoral head. Further clinical research should help validate the seemingly reliable MRI-based predictor identified by these authors.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

BOG Fracture-Risk Score Combines DNA Info with Physiological Factors

Fracture Risk Image for OBuzzThis post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson. 

During childhood and adulthood, we often put ourselves at risk for future fractures based on our activity, diet, and social habits. Many factors affect the risk of both stress fractures in younger people and fragility fractures later in life. Everyone—but especially athletes and active-duty military personnel—could benefit from an early heads-up regarding their genetic and phenotypic predisposition to stress fractures. Later in life, the FRAX index is a very useful multifactor risk score, but it is usually calculated only after a sentinel event, such as a fragility fracture.

Ultrasound is a readily available and inexpensive way to obtain an estimated heel bone mineral density (eBMD). Many common genetic variants contribute to the genetic basis for the eBMD phenotype. These variants are most commonly characterized by single nucleotide polymorphisms (SNPs, pronounced “snips”). Stanford researcher Stuart Kim developed the BMD Osteoporosis Genetic (BOG) risk score by combining 22,886 SNPs with data on height, weight, sex, and age.1 The correlation between actual eBMD and the BOG algorithm was 0.496, which was higher than the correlations achieved using the 22,886 genetic predictors or the four covariates alone.

Individuals with low BOG scores had a 17.4-fold increased risk for osteoporosis compared to those with the median BOG score. Low BOG scores were also associated with a 1.9-fold higher risk for bone fractures compared to median BOG values. However, the algorithm’s ability to discriminate cases from controls in the overall population was modest. The receiver operator area under the curve for predicting osteoporosis or fracture by the BOG algorithm was 0.78 and 0.57, respectively.

Although the effect of an individual SNP may be inconsequential, the cumulative effect from many SNPs can be large. The author stated that “an algorithm such as the BOG risk score might be useful to screen the general population…to identify individuals that warrant closer examination, such as BMD measurement via DXA [dual-energy X-ray absorptiometry].”

Reference

  1. Kim SK. Identification of 613 new loci associated with heel bone mineral density and a polygenic risk score for bone mineral density, osteoporosis and fracture. PLoS One. 2018 Jul 26;13(7):e0200785. doi: 10.1371/journal.pone.0200785. eCollection 2018. PMID: 30048462

ADHD and a Drug that Treats It Raise Risk of Some Fractures

Stress Fx for OBuzz Few physicians or patients associate attention deficit hyperactivity disorder (ADHD) with an increased risk of traumatic or stress-related fractures. However, in the June 6, 2018 issue of JBJS, a study by Ben-Ami et al. corroborates previous research suggesting that such associations exist. The authors evaluated 100,000 Israeli Defense Forces recruits and found that subjects diagnosed with ADHD were significantly more likely to sustain a traumatic fracture than recruits having no ADHD diagnosis. Furthermore, they found that recruits with ADHD who were taking the stimulant methylphenidate to treat their symptoms had a significantly increased risk of sustaining a stress fracture compared to both recruits without ADHD and recruits who had ADHD but did not take the medication.

The association between methylphenidate exposure and increased risk of stress fracture makes sense, based on animal studies showing that the drug leads to increased bone resorption. However, until now I was unaware that patients with ADHD are at an increased risk of traumatic fracture as well. The authors postulate that such an association is secondary to the fact that ADHD often manifests with compulsive or inattentive behavior that may predispose these patients to injuring themselves. That theory is further supported by this study’s finding that the risk of traumatic fracture fell when those with ADHD took stimulant medications to control their symptoms.

When one considers that upwards of 5% of school-aged children and another 4% of  adults in the US are prescribed stimulant medication (not to mention the estimated 5% to 35% of US college students who abuse stimulants without prescription), these findings take on great importance.  Because of the large number of children and adults who rely on methylphenidate to control ADHD symptoms, it is important for both primary care physicians and orthopaedic surgeons to understand the association between this medication and stress fractures.

Although limited by the vulnerabilities typically found in observational, retrospective designs, this study’s findings add to a growing body of evidence highlighting the potential fracture risks associated with stimulant medication. We probably encounter patients taking such medications on a regular basis in our practices. These data should prompt us to ask more questions of patients who have sustained stress fractures to determine whether stimulant medication usage may be an underlying cause.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

Not So Run-of-the-Mill Running Injuries

Pelvic Stress Fracture.gifLower-extremity stress fractures account for an estimated 16% of all injuries among runners. The April 2016 “Case Connections” article sprints forward from an April 13, 2016, Case Connector report about a stubborn running-related stress fracture of the inferior pubic ramus that did not respond to the usually successful conservative approach.

It’s often challenging for orthopaedists to make a diagnosis in a patient group in whom multiple musculoskeletal injuries or ailments may exist. Patients with suspected stress fractures may have radiographs with subtle, easily overlooked findings. A bone scan and/or other advanced imaging are often required to make a definitive fracture diagnosis.

Continued running due to a missed diagnosis or a patient’s ardent noncompliance can culminate in complications that may eventually require surgical intervention. The best outcomes are perhaps achieved in a setting that fosters strong collaboration between the surgeon, patient, physiatrist, and/or physical therapist with expertise in the mechanisms and physiology of running.

In a postscript to this Case Connections article, JBJS Case Connector co-editor Tom Bauer, MD describes his fateful experience with a calcaneal stress fracture while running the 2013 Boston Marathon.