Atlas / C1 Fractures




Epidemiology / Etiology


1-2% of all spinal injuries


Bimodal distribution

- mid 20s: high energy trauma

- over 80s:  low energy mechanism


Falls / MVA / Diving into shallow water


Landell's Classification


Type 1.  Isolated lateral mass fracture

- axial compression and lateral flexion


C1 lateral mass fractureAtlas lateral mass


Type 2.  Posterior AND anterior arch fractures (Jefferson)

- axial compression

- +/- transverse atlantal ligament injury


JeffersonJeff illustration 1Jefferson illustration 2


Type 3.  Posterior OR anterior arch fracture

- axial compression with hyperextension (posterior arch)

- axial compression with hyperflexion (anterior arch)


C1 posterior archarch 2


Atlas isolated anterior archArch 1


Associated injuries


High rate of concomitant spine fractures


Ylonen et al World Neurosurg 2021

- combination of X-ray, CT, MRI of 47 patients with C1 fracture
- 89% incidence of concomitant cervical spine fractures

- 76% incidence of concomitant C2 #


Associated symptoms


Vertebral artery injury

- nausea, vomiting, tinnitus, impaired vision, and drop attacks


Collet-Sicard syndrome

- posttraumatic lesion to the lower 4 cranial nerves (IX–XII)


Atlas burst fracture / Jefferson Fracture





- transverse atlantal ligament (TAL) intact



- transverse atlantal ligament (TAL) disrupted

- bony avulsions

- intra-ligamentous disruptions




1.  Lateral mass displacement (LMD)


Open mouth odontoid view

- sum of lateral mass displacement

- increased LMD suggests TAL injury


Kopparapu et al J Neurosurg Spine 2022

- Rule of Spence:  LMD > 6.9 mm predicts TAL injury, instability and need for surgery

- developed in 1970's

- inaccurate in predicting TAL injury


Eun et al Medicine 2021

- LMD > 8 mm seen in 90% of patients with transverse ligament injury



Lateral mass displacement



Increased lateral mass displacement of 8 mm


2.  C1/C2 ratio


Lin et al Medicine 2019

- C1/C2 ratio > 1.1 80% sensitive of TAL injury

- C1/C2 ratio > 1.15 100% specific of TAL injury


C12 ratio 1C12 ratio 2


3. Atlantodens interval (ADI)


> 3 mm ADI suggests TAL injury


Increased ADIADI

Lateral radiographs demonstrating increased ADI




Better defines displacement, ADI, LMD and bony avulsions of the transverse ligament


Avulsionlig avulsion

CT axial slices "Jefferson" (burst) fracture with bony avulsion (blue) of the transverse ligament


CT LMDCT Jefferson




Assess ligamentous injury, specifically transverse ligament


Dickman et al Neurosurgery 1996

- type I:  intra-substance TAL tears

- type II:  fractures or avulsions of the TAL from the tubercle of the lateral mass of the atlas



MRI demonstrating intra-ligamentous injury (blue arrow)


Jefferson MRI 1Jefferson MRI 2

MRI demonstrating avulsion of the TAL on the left side




Indications of instability

- transverse ligament avulsed / disrupted on CT / MRI
- LMD > 7 mm
- ADI > 3-5 mm
- Peg fracture




Non-operative Management




Stable fractures

- anterior / posterior arch fractures

- Jefferson with intact TAL


Unstable fractures

- ? increased union rates and better outcomes with operative management


Operative versus Nonoperative for unstable atlas fractures


Kim et al Acta Neurochir 2019

- 24 unstable atlas fractures

- 13 treated with C1/C2 fixation - 100% fusion

- 11 treated with halo-vest - 73% fusion

- reduced pain and improved outcomes with surgery


Shin et al Neurospine 2022

- 53 unstable atlas fractures

- 32/53 ORIF - 100% union

- 21 treated with halo-vest - 71% union, continued increased LMD

- those treated with halo-vest had worse neck pain and outcome scores





Halo thoracic brace


Jefferson HTB Xray

Post reduction halo xray


Jefferson Fracture Flexion Extension Views Stabe0001Jefferson Fracture Flexion Extension Views Stabe0002

Flexion and extension views demonstrating stable Jefferson fracture post halo treatment


Operative Management




1. Unstable C1 fractures

2. Non-union / ongoing instability after non-operative treatment





C1/2 fusion





- preserves C1/C2 motion


Posterior / anterior approach

- bicortical lateral mass screws

- reduction

- bridge plate / rod construct



C1/C2 fusion




Goel Harms

- C1 lateral mass screw

- C2 pedicle screw monocortical to reduce risk of vertebral artery injury

- preoperative CT angiogram important

- must avoid medial penetration of canal


Surgical technique PDF C1 C2 fusion


Vumedi technique Goel-Harms C1/C2 fusion


C1 2 fusion 1C1 2 fusion 2






He et al Spine J 2014

- 22 patients

- posterior approach and lateral mass screw / plate construct

- 100% union on CT at 9 months


Ma et al Eur Spine J 2013

- 20 patients with anterior / trans-oral approach

- lateral mass screw / plate construct

- 100% bony union at 6 months


C1 ORIF vs C1/2 Fusion


Yan et al J Neurosurg Spine 2022
- RCT (n=73) ORIF vs C1-2 fusion
- ORIF shorter operative time, reduced blood loss, less radiation, shorter hospital stay, cheaper (all p<0.001)
- improved outcomes and ROM in ORIF group