This multicenter study compared radiological parameters and clinical outcomes between surgical and nonsurgical management and investigated treatment characteristics associated with the successful management of unstable atlas fractures.
We retrospectively evaluated 53 consecutive patients with unstable atlas fracture who underwent halo-vest immobilization (HVI) or surgical fixation. Clinical outcomes were assessed using neck visual analogue scale and disability index. The radiological assessment included total lateral mass displacement (LMD) and the anterior atlantodental interval (AADI).
Thirty-two patients underwent surgical fixation and 21 received HVI (mean follow-up, 24.9 months). In the surgical fixation, but not in the HVI, LMD, and AADI showed statistically significant improvements at the last follow-up. The osseous healing rate and time-to-healing were 100% and 14.3 weeks with surgical fixation, compared with 71.43% and 20.0 weeks with HVI, respectively. Patients treated with HVI showed poorer neck pain and neck disability outcomes than those who received surgical treatment. LMD showed an association with osseous healing outcomes in nonoperative management. Clinical outcomes and osseous healing showed no significant differences according to Dickman’s classification of transverse atlantal ligament injuries.
Surgical internal fixation had a higher fusion rate, shorter fracture healing time, more favorable clinical outcomes, and a more significant reduction in LMD and AADI compared to nonoperative management. The pitfalls of external immobilization are inadequate maintenance and a lower probability of reducing fractured lateral masses. Stabilization by surgical reduction with interconnected fixation proved to be a more practical management strategy than nonoperative treatment for unstable atlas fractures.
Atlas fracture is rare and accounts for 1.3% to 2% of all spinal injuries and 2% to 13% of all cervical spine fractures [
Various surgical options for treating unstable atlas fractures with favorable outcomes have recently been introduced, such as anterior C1 ring osteosynthesis, C1 open reduction and internal fixation (ORIF), posterior C1–2 fixation, or occipitocervical fusion [
This multicenter study compared radiological parameters and clinical outcomes: patient-reported pain, neck disability, neurological impairment, and difference in the effectiveness of nonoperative management and surgical fixation in patients with unstable atlas fractures with TAL injuries.
A retrospective cohort study was conducted with approval from the local ethics committee and Institutional Review Board (approval number: 2018-10-007). In total, 116 consecutive cases with isolated or associated atlas fractures treated from January 2000 to December 2019 were obtained from 4 universities (Yonsei University, Inje University, The Catholic University, and Yeungnam University) for analysis. The inclusion criteria were isolated unstable atlas fractures identified on radiographs, > 6.9-mm LMD and confirmed fractures on 3-dimensional computed tomography (3D CT) or TAL injuries on MRI, nonoperative or surgical management performed during the acute traumatic phase, patient age of over 18 years, and a minimum follow-up period of 12 months. The exclusion criteria were stable fractures, concomitant cervical fractures, and nonacute or pathological fractures. Finally, this study included 53 patients who had unstable fractures with TAL injuries (
The diagnosis was made using modalities such as radiographs, CT, and MRI. According to the “rule of Spence,” a fracture was determined to be unstable if the total LMD overhang exceeded 6.9 mm on an open-mouth radiograph [
The total LMD and the anterior atlantodental interval (AADI) were calculated. Cervical lordosis was examined using the Cobb angle (
A patient-reported visual analogue scale (VAS) for neck pain and the Neck Disability Index (NDI) were measured preoperatively and during the last follow-up visit. The American Spinal Injury Association was used to determine the grade of neurological deficits. All patients received assessments 1 week after surgical treatment, and a follow-up visit was scheduled.
Data were expressed as mean± standard deviation or number (percentage). Paired t-test and the chi-square test were used to assess the difference in the intergroup comparison. Receiver operating characteristics (ROC) analysis was done to evaluate the sensitivity and specificity of LMDs as an objective measure of non-combination. The optimal cutoff value for LMD was determined using the maximum Youden index (sensitivity– [1 – specificity]) [
All 53 patients had unstable atlas fractures according to the “rule of Spence” ( > 6.9-mm preoperative LMD); 32 patients underwent surgical reduction with interconnected fixation and 21 patients underwent nonsurgical management (HVI) to achieve osseous healing. The mean age at the time of management was 48.23± 14.62 years (range, 23–69 years). Patients were followed for a mean of 24.9 months (range, 15.53–38.61 months). Among the 53 patients, 37 were injured in a vehicle accident, 7 were injured by diving into a pool, and 9 were injured by falling. The mean time from injury to management was 2.68± 1.72 days (
Thirty-two patients (16 with Landells and Van Peteghem type II and 16 with type III fractures) underwent surgical fixation, and 21 patients (9 with Landells and Van Peteghem type II and 12 with type III fractures) were treated with nonoperative management. Regarding surgical methods, 27 patients received C1–2 fixation with crosslink compressors, 4 were treated with C1 ORIF, and 1 had C1-2-3 fixation.
There were 29 Dickman classification type I TAL injuries (17 in the surgical fixation and 12 in the nonsurgical management groups) and 24 type II injuries (15 in the surgical fixation and 9 in the nonsurgical management groups) (p= 0.776).
Baseline demographics according to treatment modality are presented in
Patients who received nonsurgical management experienced more severe neck pain than those treated with surgical internal fixation. The preoperative NDI score was higher in the surgical fixation group than in the nonsurgical management group. At the last follow-up, the NDI score was 7.13± 2.04 in the surgical fixation group and 11.29± 6.46 in the nonsurgical management group (
No significant differences in LMD or AADI were found according to Dickman’s classification of TAL injuries. The osseous healing rate was not significantly different in the surgical fixation and nonsurgical management groups based on the classification of TAL injuries (
In the nonsurgical management group, the ROC analysis found that the optimal cutoff value of the preoperative LMD between osseous healing and nonunion was 8.86, with sensitivity and specificity values of 83.33% and 73.33%, respectively. The area under the curve was 0.767 (95% confidence interval [CI], 0.533– 0.921; p= 0.034) (
One of the 32 patients treated with surgical reduction with fixation suffered cerebellar infarction [
Surgical internal fixation enabled a better reduction of fractured lateral slippage and widened AADI than nonsurgical management. The osseous healing was 100% with surgical internal fixation but 71.43% with nonsurgical management, indicating that external immobilization with halo-vest devices offered insufficient fixation of occipitocervical motion. Clinically, the patients who received nonsurgical management experienced poorer neck pain and more frequent disability compared to those treated with surgical internal fixation. There were no differences in clinical outcomes and osseous healing between surgical and conservative management based on Dickman’s classification of TAL injury. A preoperative LMD greater than 8.86 mm predicted poor osseous healing, defined by nonunion, in unstable atlas fractures that underwent nonsurgical management.
The goal for treatment of unstable atlas fractures is to reduce fracture displacement, maintain stabilization, and heal the bony fracture. Various surgical options for treating unstable atlas fractures with ligament tears have been recently described with advanced surgical techniques and good radiological outcomes [
Dickman’s TAL injury type has been considered a critical factor in determining the stability of atlas fractures and choosing a treatment strategy. Dickman et al. proposed that type I TAL injuries, in which a rupture occurs in the substance of the ligament, should be implemented early with surgery [
Recent studies have reported that the ‘‘rule of Spence’’ was inaccurate for identifying TAL injuries [
Kim et al. [
We recommend surgical treatment for unstable and displaced atlas fractures. If a transverse ligament disruption exists with an atlas fracture and the TAL injury violates the rule of Spence or shows predominant signs of TAL injuries (e.g., hypersignal intensity on gradient echo imaging, ligament discontinuity, or insertion site bleeding), surgical reduction and interconnected fixation will correct the incompetence of the transverse ligament (
All modalities, such as radiographs, CT, and MRI, should be used to diagnose C1 fractures. Initially, radiographs should be taken, including anteroposterior, lateral, and open-mouth x-rays. The open-mouth view provides effective visualization of the C1, C2 body, atlantoaxial joints, odontoid process, and lateral spaces between the lateral border of the C2 body and lateral masses of C1 (when the patient’s shoulders are on the same horizontal plane to prevent rotation and the midsagittal plane is perpendicular to the plane of the table).
CT scan is the screening method of choice in many trauma centers. In this study, CT was performed to assess fractures, such as the presence of an avulsion fracture at the TAL insertion site, a comminuted fracture, or a lateral mass. CT offers a more precise resolution of bony fragments associated with atlas fracture and is not susceptible to magnification error [
The transverse ligament should be directly imaged with MRI, as it is a more sensitive indicator of TAL disruption than the “rule of Spence” or CT. MRI scans, including axial and coronal thin-section T1- and T2-weighted images and gradient echo images, should be performed to identify TAL injuries based on anatomical disruption, the presence of fluid signal, ligament discontinuity, or insertion site bleeding. When making decisions regarding treatment and imaging modalities for C1 fractures, transverse ligament injuries with associated C1–2 instability were determined based on > 6.9-mm LMD on open-mouth radiograph and confirmed fractures, such as avulsion fracture at the TAL insertion site, a comminuted fracture, or a lateral mass on CT and documented disruption of TAL on MRI.
This study, in its nature, has several limitations. First, this was a retrospective study with relatively few patients, and inherent differences between groups were inevitable. In addition, some concerns have been raised regarding late fusion in cases of pseudoarthrosis due to the short-term follow-up. Selection bias due to the multicenter design of the study likely affected the decision to manage unstable fractures. Furthermore, management strategies were determined by the treating surgeon, and differences in regional, institutional, and surgeon preferences might have impacted nonoperative management with HVI or surgical treatment, including whether C1 ORIF, posterior C1–2 fixation, or occipitocervical fusion was performed. An optimal treatment modality for unstable atlas fractures could not be determined from this comparative study as it was a retrospective study with few enrolled patients, which could lead to possible bias. In the future, additional prospective and multicenter studies should be conducted to derive radiological and clinical outcomes in patients who have executed surgical internal fixation or nonsurgical external immobilization for unstable atlas fractures. Nonetheless, we hope that the present study findings will be helpful in the management of patients with unstable atlas fractures.
The radiological outcomes of surgical treatment were superior to those of nonsurgical treatment. Surgical internal fixation of unstable atlas fractures had a higher fusion rate, a shorter fracture healing time, and better reduction of fractured lateral masses than nonoperative management. The pitfalls of conservative management for unstable atlas fractures are inadequate maintenance and a lower likelihood of reducing fractured lateral masses. Clinically, patients with nonsurgical management experienced poorer neck pain and disability more frequently compared to those treated with surgical internal fixation. In this study, clinical outcomes and osseous healing were not significantly different between surgical and conservative management based on Dickman’s classification of TAL injury. An LMD greater than 8.86 mm was associated with a high probability of poor osseous healing after nonoperative treatment. Therefore, surgical reduction with interconnected fixation for cases with an LMD greater than 8.86 mm may lead to more favorable osseous healing over nonsurgical management.
Supplementary Figs. 1-2 can be found via
Atlantoaxial joint fusion without crosslink fixation.
C1 open reduction and internal fixation.
The authors have nothing to disclose.
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conceptualization: JJS, KK, JK, HJL, JTH, YH; Data curation: JJS, KK, JS, JK, HJL, TWK, JTH, SK, YH; Formal analysis: JJS, KK, JS, JK, HJL, TWK, YH; Funding acquisition: KK, JK, JTH, SK, YH; Methodology: JJS, KK, JS, JK, HJL, TWK, JTH, SK, YH; Project administration: KK, HJL, TWK, JTH, SK, YH; Visualization: JJS, JK, TWK, JTH, SK, YH; Writing - original draft: JJS, JS; Writing - review & editing: KK, JS, HJL, JTH, YH.
The authors would like to thank Joongkyum Shin for their contributions in drafting and revising the manuscript for important intellectual content. The authors also wish to thank all the subjects who participated in the study, as well as the support staff and the research coordinator.
Patient flowchart. HVI, halo-vest immobilization.
Radiological measurements. (A) In an open-mouth view, the sum of (a) and (b) is greater than 6.9 mm, and the rule of Spence suggests a transverse ligament injury. (B) The anterior atlantodental interval (AADI) and cervical lordosis (CL) are shown in the picture.
Reduction of total lateral mass displacement after surgical and nonoperative management. The surgical reduction and fixation group showed no loss of reduction in fractured lateral masses in the initial measurements (9.86±1.59 mm) and those obtained 7 days (5.95±2.54 mm), 3 months (5.96±2.55 mm), and 12 months (6.08±2.27 mm) after surgery. In the nonoperative group treated with HVI, initial (9.35±1.21 mm) cervical traction followed by halo-vest immobilization (HVI) was found to lead to slight reductions in lateral dislocation at 7 days (7.75±1.54 mm), 3 months (8.14±1.95 mm), and 12 months (8.27±2.02 mm) after HVI, but increased displacement continued to occur over time.
Receiver operating characteristic (ROC) curves for the preoperative total lateral mass displacement (LMD). The best cutoff value of the preoperative LMD between osseous healing and nonunion was 8.86 mm. The area under the curve (AUC) was 0.767 (95% confidence interval, 0.533–0.921, p=0.0342).
Halo-vest immobilization. (A) Preoperative open-mouth view with a sum of overhangs of the C1 lateral masses on the C2 facet of 8.71 mm. (B) The sum of lateral displacements of the fractured lateral masses was 7.67 mm 7 days after halo-vest immobilization (HVI). (C) The same value was 7.39 mm 3 months after HVI. (D) The 6-month posttreatment value was 8.41 mm. There was a loss of reduction in the fractured atlas ring over time.
Surgical reduction and fixation with crosslinking. (A) Preoperative open-mouth view shows that the sum of the overhang of the C1 lateral masses on the C2 facet was 8.1 mm. (B) On computed tomography (axial view), a right anterior arch fracture and right lateral mass fracture (Landells & Van Peteghem type II) are shown. (C) There was a rupture of the transverse atlantal ligament (Dickman type II). A tear of the transverse ligament (arrow). (D) Surgical reduction and fixation with crosslinking were performed. The 12-month postoperative value was 3.8 mm.
Patient demographics (n=53)
Characteristic | Value |
---|---|
Age (yr) | 48.23 ± 14.62 |
Sex, male:female | 32:21 |
Mechanism of injury | |
MVA | 37 |
Fall down | 16 |
BMI (kg/m2) | 26.53 ± 4.26 |
BMD (T-score) | -1.67 ± 1.38 |
Smoking | 29 (54.7) |
Diabetes | 11 (20.8) |
Management starting time (day) | 2.68 ± 1.72 |
Management | |
Surgical reduction with fixation | 32 (60.4) |
HVI | 21 (39.6) |
Fracture type |
|
II | 25 (47.2) |
III | 28 (52.8) |
TAL injury type |
|
I | 29 (54.7) |
II | 24 (45.3) |
ASIA grade E | 53 |
Values are presented as mean±standard deviation or number (%).
MVA, motor vehicle accident; BMI, body mass index; BMD, bone mineral density; HVI, halo-vest immobilization; ASIA, American Spinal Injury Association Impairment Scale; fracture type.
Landells & Van Peteghem classification.
Transverse atlantal ligament injury Dickman classification.
Patient demographics according to treatment modality
Variable | Surgical group (n = 32) | Nonsurgical group (n = 21) | p-value |
---|---|---|---|
Age (yr) | 48.47 ± 15.96 | 47.86 ± 12.68 | 0.964 |
Sex, male:female | 17:15 | 15:6 | 0.187 |
Mechanism of injury | 0.417 | ||
MVA | 21 | 16 | |
Fall down | 11 | 5 | |
BMI (kg/m2) | 25.81 ± 2.64 | 30.33 ± 9.24 | 0.092 |
BMD (T-score) | -1.36 ± 1.41 | -2.23 ± 1.30 | 0.340 |
Smoking | 15 (46.9) | 14 (66.7) | 0.161 |
Diabetes | 5 (15.6) | 6 (28.6) | 0.260 |
Management starting time (day) | 2.64 ± 1.43 | 2.71 ± 2.00 | 0.689 |
Fracture type |
0.614 | ||
II | 16 (50.0) | 9 (42.9) | |
III | 16 (50.0) | 12 (37.5) | |
TAL injury type |
0.776 | ||
I | 17 (53.1) | 12 (37.5) | |
II | 15 (46.9) | 9 (42.9) | |
ASIA grade E | 32 | 21 | - |
Values are presented as mean±standard deviation or number (%).
MVA, motor vehicle accident; BMI, body mass index; BMD, bone mineral density; TAL, transverse atlantal ligament; ASIA, American Spinal Injury Association Impairment Scale; fracture type.
Landells & Van Peteghem classification.
Transverse atlantal ligament injury Dickman classification.
Radiological parameters and clinical outcomes according to the treatment modality
Variable | Surgical fixation (n = 32) | Nonsurgical management (n = 21) | p-value |
---|---|---|---|
LMD (mm) | |||
Preoperative | 9.86 ± 1.59 | 9.35 ± 1.21 | 0.212 |
Postoperative 7 days | 5.95 ± 2.54 | 7.75 ± 1.54 | 0.002 |
Postoperative 3 months | 5.96 ± 2.55 | 8.14 ± 1.95 | 0.001 |
Postoperative 12 months | 6.08 ± 2.27 | 8.27 ± 2.02 | 0.001 |
AADI (mm) | |||
Preoperative | 4.95 ± 0.57 | 4.90 ± 0.72 | 0.986 |
Postoperative 12 months | 3.00 ± 1.05 | 4.30 ± 0.87 | < 0.001 |
Osseous healing time (wk) | 14.38 ± 2.93 | 20.02 ± 8.73 | 0.003 |
Healing rate (%) | 100 | 71.43 | 0.002 |
C2–7 Cobb angle (°) | |||
Preoperative | 6.53 ± 4.45 | 4.06 ± 3.86 | 0.288 |
Postoperative 12 months | 11.80 ± 7.38 | 6.54 ± 7.19 | 0.002 |
C2–7 ROM (°) | |||
Postoperative 12 months | 54.38 ± 14.41 | 63.82 ± 29.24 | 0.253 |
Neck VAS | |||
Preoperative | 7.31 ± 0.78 | 7.19 ± 0.68 | 0.561 |
Postoperative 12 months | 1.91 ± 0.53 | 3.00 ± 1.52 | 0.003 |
NDI | |||
Preoperative | 24.25 ± 5.49 | 21.04 ± 4.59 | 0.032 |
Postoperative 12 months | 7.13 ± 2.04 | 11.29 ± 6.46 | 0.025 |
Values are presented as mean±standard deviation unless otherwise indicated.
LMD, total lateral mass displacement; AADI, anterior atlantodental interval; ROM, range of motion; VAS, visual analogue scale; NDI, Neck Disability Index.
p<0.05.
Radiological parameters and clinical outcomes according to the TAL injury
Variable | Dickman type I (n = 29) | Dickman type II (n = 24) | p-value |
---|---|---|---|
Preoperative LMD (mm) | 9.79 ± 1.48 | 9.51 ± 1.45 | 0.486 |
Preoperative AADI (mm) | 4.93 ± 0.69 | 4.80 ± 0.57 | 0.463 |
Treatment modalities | |||
Surgical fixation | 17 | 15 | |
HVI | 12 | 9 | 0.776 |
Osseous healing (%) | |||
Surgical fixation | 17/17 (100) | 15/15 (100) | - |
HVI | 9/12 (75) | 6/9 (66.7) | 0.683 |
Neck VAS | |||
Preoperative | 7.28 ± 0.75 | 7.25 ± 0.74 | 0.900 |
Postoperative 12 months | 2.24 ± 1.24 | 2.46 ± 1.06 | 0.264 |
NDI | |||
Preoperative | 23.24 ± 5.49 | 22.67 ± 5.26 | 0.701 |
Postoperative 12 months | 8.72 ± 3.80 | 8.83 ± 5.82 | 0.335 |
Values are presented as mean±standard deviation or number (%).
TAL injury, transverse atlantal ligament injury Dickman classification; LMD, total lateral mass displacement; AADI, anterior atlantodental interval; HVI, halo-vest immobilization; VAS, visual analogue scale; NDI, Neck Disability Index.