Risk Factors for Fracture Nonunion and Transverse Atlantal Ligament Injury After Isolated Atlas Fractures: A Case Series of 97 Patients

Abstract

BACKGROUND:The management of atlas fractures is controversial and hinges on the integrity of transverse atlantal ligament (TAL). OBJECTIVE: To identify risk factors for atlas fracture nonunion, with and without TAL injury. METHODS: All isolated, traumatic atlas fractures treated at our institution between 1999 and 2016 were analyzed. Multivariable logistic regression was used to identify variables associated with TAL injury confirmed on MRI, occult TAL injury seen on MRI but not suspected on computed tomography (CT), and with fracture nonunion on follow-up CT at 12 weeks. RESULTS: Lateral mass displacement (LMD) ≥ 7 mm had a 48.2% sensitivity, 98.3% specificity, and 82.6% accuracy for identifying TAL injury. MRI-confirmed TAL injury was independently associated with LMD > 7 mm (P = .004) and atlanto-dental interval (P = .039), and occult TAL injury was associated with atlanto-dental interval (P = .019). Halo immobilization was associated with having a Gehweiler type 3 fracture (P = .020), a highrisk injury mechanism (P = .023), and an 18.1% complication rate. Thirteen patients with TAL injury on MRI and/or LMD ≥ 7 mm were treated with a cervical collar only, and 11 patients (84.6%) healed at 12 weeks. Nonunion rates at 12 weeks were equivalent between halo (11.1%) and cervical collar (12.5%). Only age independently predicted nonunion at 12 weeks (P = .026). CONCLUSION: LMD > 7 mm on CT is not sensitive for TAL injury. Some atlas fractures with TAL injury can be managed with a cervical collar. Nonunion rates are not different between halo immobilization and cervical collar, but a strong selection bias precludes directly comparing the efficacy of these modalities. Age independently predicts nonunion.

Surgery Decreases Nonunion, Myelopathy, and Mortality for Patients With Traumatic Odontoid Fractures: A Propensity Score Matched Analysis

“…The following variables were controlled for when assessing the effect of surgery on nonunion: age, fracture type, angulation, displacement ≥3 mm, and comminution. 23 The following variables were controlled for when assessing mortality: age, sex, ISS, presenting Nurick score, CCI, and ICU admission. The following variables were controlled for when assessing predictors of Nurick scores at follow-up: age, sex, presenting Nurick score, surgical stabilization, CCI, type II fracture, fracture angulation, and ISS.…”

“…We do so while controlling for age, sex, comorbid disease burden, neurological status, ISS, and selection for ICU admission. We similarly assess the effect of surgery on fracture nonunion, controlling for multiple relevant features including age, 1 , 22 , 23 Anderson-D’Alonzo fracture type, 24 fracture angulation, 25 comminution, 26 and displacement. Moreover, we use ordinal multivariable logistic regression to examine the effect of surgical stabilization on myelopathy as measured by the Nurick score.…”

Atlas fractures with and without simultaneous dens fractures differ with respect to clinical, demographic, and management characteristics

“…[ 21 ] Indeed, we found a marked age difference of 16 years between these populations, and older age is associated with atlas fracture nonunion. [ 18 , 22 , 23 ] Moreover, age affects management, as halo use for atlas fractures in patients age ≥50 is associated with complications. [ 21 ] Horn et al .…”