• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Home
  • Online Consultation
  • About
  • Newsletter/Updates
  • Contact Us
  • Policies

Bone and Spine

Orthopedic health, conditions and treatment

  • General Ortho
  • Procedures
  • Spine
  • Upper Limb
  • Lower Limb
  • Pain
  • Trauma
  • Tumors

Dens or Odontoid Fractures

By Dr Arun Pal Singh

In this article
    • Anatomy of Odontoid Process or Dens
      • Anatomy of axis vertebra
      • Range of Motion of Cervical Spine
      • Blood Supply of Odontoid
      • Fracture Pattern
      • Anderson and D’Alonzo Classification of Odontoid Fractures
    • Clinical Presentation
    • Imaging
    • Treatment of Dens Fractures
      • Nonoperative Treatment
      • Surgical Treatment
      • Related

Odontoid fractures are fractures of dens or odontoid process of axis vertebra or C2. Dens is a strong, tooth-like process projecting upwards from the body of the axis.

Fractures of the axis make up 27% of all cervical spine injuries. Fractures of the odontoid process are the most common subtype of axis fractures (41%). Odontoid fractures account for 10-15% of all cervical fractures.

These fractures occur in young patients and the elderly in a bimodal fashion. Whereas in young patients the fractures are as a result of blunt trauma to head leading to cervical hyperflexion or hyperextension, in elderly people these occur by simple fall. Elderly people also have higher morbidity and mortality.

Anatomy of Odontoid Process or Dens

Anatomy of axis vertebra

Axis vertebra has an odontoid process or dens and body. The cartilaginous junction between the dens and vertebral body that does not fuse until 6 years of age and should be kept in mind so as not to misdiagnose it as fracture.

Range of Motion of Cervical Spine

Occipital-C1-C2 ligamentous stability is provided by the odontoid process and its supporting ligaments. Transverse ligament limits the anterior translation of the atlas. Both apical ligaments and alar ligaments limit rotation of the upper cervical spine

The odontoid is derived from mesenchyme of the first cervical vertebra. During development, it becomes separated from the atlas and fuses with the axis.

The apex, or tip, of the odontoid, is derived from the most caudal occipital sclerotome, or proatlas.

This separate ossification center, ossiculum terminale, appears at age 3 years and fuses by age 12 years.

Blood Supply of Odontoid

Vertebral and carotid arteries form the main source of blood supply to odontoid. Anterior ascending artery and posterior ascending artery are branches of vertebral artery beginning at the level of C3. They ascend anterior and posterior to the odontoid and meet superiorly to form an apical arcade.

Cleft perforators come from of the extracranial internal carotid artery and supply the superior portion of the odontoid.

The apex of the odontoid is supplied by branches of the internal carotid artery and base is supplied from branches of the vertebral artery.

Os Odontoideum

This condition was earlier thought to be a failure of fusion at the base of the odontoid but new evidence has suggested the likelihood of residual old traumatic process. An os odontodeum can be divided into two main types

  • Orthotopic: the normal position with a wide gap between C2 and os)
  • Dystopic: displaced

It could be confused with odontoid fractures and the treatment is mostly observation

Fracture Pattern

The displacement of the fragment could be anterior (hyperflexion) or posterior (hyperextension). Anterior displacement is associated with transverse ligament failure and atlantoaxial instability.

Posterior displacement is caused by direct impact from the anterior arch of atlas during hyperextension.

Anderson and D’Alonzo Classification of Odontoid Fractures

Type I  Odontoid Fractures

These type of odontoid fractures involve the tip of dens at the insertion of the alar ligament. These are usually stable fractures but may be associated with atlanto-occipital dislocation. These constitute about 5% of odontoid fractures. Generally, it is a stable fracture.

Type II Odontoid Fractures

These are the most common odontoid fractures and account for 60% of the cases. Fractures occur at the base. These fractures are associated with a higher rate of nonunion.

odontoid fractures Classification
odontoid fractures Classification

 Type III Odontoid Fractures

Accounts for 30% of the fractures. Fractures occur through the body of C2 and do not actually involve dens. These are unstable fracture as the atlas and occiput can now move together as a unit

Clinical Presentation

Patients present with neck pain that worsens with the motion of the neck.  Other findings may be

  • Motor power loss ranging to quadriplegia
  • Feeling of the instability of head on the spine
  • Dysphagia may be present when associated with a large retropharyngeal hematoma

Imaging

Xrays

AP, lateral, open-mouth odontoid view of the cervical spine is commonly done in injury to the upper cervical spine and odontoid fractures. Fracture pattern is best seen on open-mouth odontoid.

Flexion-extension radiographs are important to diagnose occipitocervical instability in Type I odontoid fractures and Os odontoideum.

Instability defined as atlanto-dens-interval > 10mm and < 13mm space available for cord.

CT/MRI

CT scan would be best for fracture delineation and to assess the stability of the fracture pattern. CT angiogram is required to determine the location of vertebral artery prior to posterior instrumentation procedures. MRI is indicated if the neural loss is there.

Treatment of Dens Fractures

Os Odontoideum patients require observation in most of the cases. Type I fractures are managed by cervical orthosis. Type II in young patients can be managed in halo brace if risk factors for nonunion are not present. Otherwise, they should be operated. In elderly patients who are not candidates for surgery, type II fractures are managed with cervical orthoses.

Type III fractures are treated with Cervical Orthosis

Nonoperative Treatment

Observation

Os odontoideum and in cases with no neurologic symptoms or instability.

Hard Cervical Orthosis

These are worn for 6-12 weeks in patients with type I and type II in elderly who are not surgical candidates. The union may not occur in these cases but a fibrous union provides enough stability.

Halo Vest Immobilization

It is done in young patients with no risk factors for nonunion. This is also worn for 6-12 weeks.

Surgical Treatment

Posterior C1-C2 fusion

This involves fusion of first and second vertebra posteriorly. This treatment is considered in patients with

  • Type II fractures with risk factors for nonunion.
  • Type II/III fracture nonunions
  • Os odontoideum with neurologic deficits or instability
  • Type I with atlantooccipital instability (extremely rare)

Anterior Odontoid Osteosynthesis

This involves the surgical fixation of the fracture. This is done in patients with type II fractures with risk factors for nonunion and acceptable alignment and minimal displacement provided fracture pattern allow proper screw placement. It is associated with higher failure rates than posterior C1-2 fusion

Transoral Odontoidectomy

Odontoid is removed when there is severe posterior displacement of dens with spinal cord compression and neurologic deficits

Image Credit: http://www.jaaos.org/content/18/7/383/F1.large.jpg

Related

Spread the Knowledge
8
Shares
 
8
Shares
17   

Filed Under: Spine

About Dr Arun Pal Singh

Arun Pal Singh is an orthopedic and trauma surgeon, founder and chief editor of this website. He works in Kanwar Bone and Spine Clinic, Dasuya, Hoshiarpur, Punjab.

This website is an effort to educate and support people and medical personnel on orthopedic issues and musculoskeletal health.

You can follow him on Facebook, Linkedin and Twitter

Primary Sidebar

Browse Articles

Representative picture for things to do to achieve fastr fracture healing

7 Tips for Faster Fracture Healing

Fractures are very common in modern life. Reported annual occurrence in the US is about 7 million. Fracture healing can take any time between 4-12 weeks depending on the bone injured and the treatment given. Because of inconvenience and adverse effects on daily activities of living, everyone looks for ways of faster fracture healing. But […]

femur bone

Femur Anatomy and Attachments

The femur is also called the thigh bone and is the longest and strongest bone of the body. It is composed of an upper end, a lower end and a shaft. The upper and bears a rounded head, whereas the lower end is widely expanded to from two large condyles. The head is directed medially. The […]

Classification of Osteochondral lesions of talus

Osteochondral Lesions of Talus

Osteochondral lesions of talus represent approximately 4% of all cases of osteochondral lesions. Previously terms like osteochondritis dessicans, transchondral talus fracture, and osteochondral talus fracture have been used to describe these lesions which involve cartilage as well as the bone of the talus. A history of trauma is documented in more than 85% of patients […]

Hydatid Cyst of Bone

Hydatid Disease of Bone

Hydatid disease of bone is very rare and is often misdiagnosed because of non-specific presentation and radiology. As its management is quite different from other conditions involving the bone, it is important to consider the differential of Hydatid disease of the bone in lucent bone lesions, especially where the echinococcosis is prevalent. Hydatid Disease or […]

Cervical Spondylosis with severe anterior osteophytes cervical spine

Cervical Spondylosis- Causes, Presentation and Treatment

Cervical spondylosis is a term for degenerative changes (wear and tear) of the vertebral discs and facets of the cervical spine. It is considered to be a normal part of aging. It is not symptomatic in many people but may cause recurring neck pain. Cervical Spondylosis often progresses with age and frequently involves multiple levels. […]

muckle wells syndrome

Muckle Wells Syndrome

Muckle-Wells syndrome [Also known by the names of  UDA (Urticaria Deafness Amyloidosis) syndrome   is a rare autosomal dominant disease which results in Sensorineural deafness Recurrent hives Amyloidosis – A disease where abnormal deposition of amyloid occurs in various organs. Fevers Painful joints (arthritis) Muckle-Wells syndrome was first described in 1962 by Thomas James Muckle and […]

Canadian C-Spine Rule

Canadian C-spine Rule

Canadian C-Spine Spine Rule For Risk of Skeletal Injury Canadian C-spine rule is for use of radiography in cervical spine injuries. Cervical spine injury has the potential for neurological injury and various protocols have been developed to protect the C-spine from field to hospital emergency care. These protective measures like a backboard, collar and sandbags […]

© Copyright: BoneAndSpine.com
Manage Cookie Consent
The site uses cookies. Please accept cookies for a better visiting experience.
Functional Always active
The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network.
Preferences
The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user.
Statistics
The technical storage or access that is used exclusively for statistical purposes. The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
Manage options Manage services Manage vendors Read more about these purposes
View preferences
{title} {title} {title}
 

Loading Comments...