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
What’s New in Pediatric Orthopaedics 2018
Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.
This month, Derek Kelly, MD, co-author of the February 21, 2018 Specialty Update on Pediatric Orthopaedics, selected the most clinically compelling findings from among the more than 50 studies summarized in the Specialty Update.
Trauma
—An analysis of pediatric femoral shaft fractures before and after the publication of clinical practice guidelines1 revealed a significant increase in the use of interlocked intramedullary nails in patients younger than 11 years of age, and an increase in surgical management for patients younger than 5 years of age. Considerable variability among level-I pediatric trauma centers highlights the need for further outcome studies to facilitate updating of existing guidelines.
Scoliosis
—A prospective cohort study of pain and opioid use among patients following posterior spinal fusion for adolescent idiopathic scoliosis found that increased age, male sex, greater BMI, and preoperative pain levels were associated with increased opioid use. Findings like these may help guide clinicians in opioid dispensing practices that minimize the problem of leftover medication.
Infection
—Two stratification/scoring systems may aid in the early prediction of musculoskeletal infection severity and promote efficient allocation of hospital resources. A 3-tiered stratification system described by Mignemi et al.2 correlated with markers of inflammatory response and hospital outcomes. Athey et al.3 validated a severity-of-illness score and then modified it for patients with acute hematogenous osteomyelitis.
Hip
—A study of closed reduction for developmental dysplasia of the hip4 revealed that 91% of 87 hips achieved stable closed reduction. Of those, 91% remained stable at the 1-year follow-up. Osteonecrosis occurred in 25% of cases, but it was not associated with the presence of an ossific nucleus, a history of femoral-head reducibility, or age at closed reduction.
—Regardless of obesity status, serum leptin levels increase the odds of slipped capital femoral epiphysis (SCFE), according to a recent study. Researchers reached that conclusion after comparing serum leptin levels in 40 patients with SCFE with levels in 30 BMI-matched controls.
References
- Roaten JD, Kelly DM, Yellin JL, Flynn JM, Cyr M, Garg S, Broom A, Andras LM,Sawyer JR. Pediatric femoral shaft fractures: a multicenter review of the AAOS clinical practice guidelines before and after 2009. J Pediatr Orthop.2017 Apr 10. [Epub ahead of print].
- Mignemi ME, Benvenuti MA, An TJ, Martus JE, Mencio GA, Lovejoy SA, Copley LA, Williams DJ, Thomsen IP, Schoenecker JG. A novel classification system based on dissemination of musculoskeletal infection is predictive of hospital outcomes. J Pediatr Orthop.2016 Jun 13. [Epub ahead of print].
- Athey AG, Mignemi ME, Gheen WT, Lindsay EA, Jo CH, Copley LA. Validation and modification of a severity of illness score for children with acute hematogenous osteomyelitis. J Pediatr Orthop.2016 Oct 12. [Epub ahead of print].
- Sankar WN, Gornitzky AL, Clarke NM, Herrera-Soto JA, Kelley SP, Matheney T, Mulpuri K, Schaeffer EK, Upasani VV, Williams N, Price CT; International Hip Dysplasia Institute. Closed reduction for developmental dysplasia of the hip: early-term results from a prospective, multicenter cohort. J Pediatr Orthop.2016 Nov 11. [Epub ahead of print].
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