The atlanto-axial joint is one of the complex and important joint in the body. The Atlantoaxial joint stabilizes the neck during activities and at rest. Ligaments and tendons supports Atlanto-axial joint. Non-displaced fracture or dislocation of Atlanto-axial joint results in severe pain, numbness and weakness in upper extremities. Displaced fracture or dislocation of the Atlanto-axial joint may cause life-threatening complications.1 In this article, we will discuss the anatomical details of Atlanto-axial Joint, causes, injuries and treatment of injuries resulting in fracture or dislocation of Atlanto-axial joint.
How Do We Define Atlanto-Axial Dislocation And Fracture?
- Atlanto-Axial Joint Function-
- Atlanto-axial joint is the junction between neck and skull (head).
- Encloses and supports spinal cord.
- The spinal cord is least reinforced in neck compared to thorax and abdomen.
- About Atlanto-Axial Joint-
- Atlanto-axial joint is the joint between first and second cervical vertebra.
- First cervical vertebra is known as atlas and second cervical vertebra is known as axis vertebrae.
- The joint is formed between odontoid process of axis (second cervical vertebrae) and the posterior surface of atlas (first cervical vertebra).
- Odontoid process is covered by a ligament that is attached to posterior surface of atlas on the side of odontoid process. Ligament forms a ring around odontoid process.
- Upper part of the joint and first cervical vertebrae protects the lower section of brain stem known as medulla
- Ligaments Supporting The Atlanto-Axial Joint
- Anterior Atlanto-axial Ligament
- Posterior Atlanto-axial ligament
- Transverse ligament of atlas
- Dislocation and Fracture of Atlanto-Axial Joint-
- Anterior protrusion of axis vertebrae is known as the Odontoid Process.
- Odontoid process facilitates stability of the joint.
- Fall or whiplash injury may cause injury or fracture of Odontoid Process, body of atlas or axis vertebra.
- Fracture or dislocation of odontoid process weakens the joint and results in weak joint.1
- Neck movement may result in further dislocation or fracture of the joint.
- Cervical Spinal Cord-
- Cervical spinal cord is covered by Atlanto-axial joint and cervical vertebra.
- Spinal cord at cervical level carries nerve fibers to entire body except face and skull.
- Spinal cord injury could be partial or complete injury.
- Partial injury may cause numbness or weakness in upper extremity.
- Complete injury of spinal cord may cause quadriplegia or paralysis of all 4 extremities.
- Non-displaced Fracture Or Dislocation of Atlanto-Axial Joint
- Non-displaced fracture or dislocation does not cause life threatening events or injury.2
- Non-displaced fracture causes severe pain.
- Non-displaced fracture is often unstable and may cause displacement of section of the bone if not stabilized.
- Immediately following head or neck injury, head and neck is stabilized to prevent displacement of fractured bones.
- Displaced Fracture or Dislocation of Atlanto-Axial Joint
- Displaced Atlanto-axial Dislocation1 or Fracture can cause severe spinal cord compression resulting in significant neurological injuries of upper spinal cord and lower medulla oblongata.
- Patient may suffer paralysis of all 4 extremities (quadriplegia).
Causes Of Atlanto-Axial Dislocation And Fracture
- Direct Trauma-3
- Domestic fall
- Automobile or car accident
- Work accident
- Bone Disorders
Symptoms Of Atlanto-Axial Dislocation And Fracture
Chronic Pain Caused By Atlanto-Axial Joint Fracture And Dislocation-
- Anatomical Distribution Of Pain
- Severe neck pain is spread over back of the neck and arms.
- Intensity of Pain
- Severe to extreme severe
- Continuous chronic pain.
- Chronic pain lasts for more than 6 months even after healing of fracture and dislocation.
- Neuropathic Pain
- Pain is hyperalgesia in characteristics.
- Character of Pain
- Pins and needle type of pain
- Pain Is Referred To
- Upper extremities, neck and thorax.
Headache Associated With Atlanto-Axial Dislocation And Fracture-
- Occipital headache
- Tension type headache
Range of Neck Movement-
- Restricted range of movements
- Restricted flexion, extension and rotation of neck
Compression of Spinal Cord Caused By Dislocation Or Fracture Of Atlanto-Axial Joint-
- Sensory Dysfunction-
- Tingling and numbness in upper extremity, neck and chest wall.
- Paresthesia bilateral upper extremities
- Motor Dysfunction
- Alteration in the ability to ambulate
- Weakness of upper and lower extremities
- Breathing difficulties
- Bladder and Bowel Dysfunction
- Bladder and bowel incontinence
- Incomplete Spinal cord injury caused by Atlanto-axial joint dislocation or fracture results in weakness of neck muscles resulting in torticollis.
- Dystonia– Movement disorder caused by abnormal muscle contractions.
- Asymmetrical neck position
- Observed following incomplete spinal cord injury
- Isolated motor nerve injury
- Injury of anterior segment of spinal cord
- Seen in quadriplegic patient
- Tear or section of motor nerve to arms and neck
- Gait disturbances are caused by muscle weakness resulting in abnormal walking.
- Gait disturbance is caused by abnormalities of strength, sensation and coordination.
Diagnosis Of Atlanto-Axial Dislocation And Fracture
- X-Ray shows the separation of the Atlanto-axial joint when injury causes dislocation or fracture.
- Computerized Tomography (CT) Scan
- Bone study- shows fracture and dislocation
- Spinal cord study- shows spinal compression or spinal stenosis.
- Magnetic Resonance Imaging (MRI)
- Bone study- shows fracture and dislocation of atlanto-axial joint
- Displacement of odontoid process
- Spinal cord study- shows spinal compression or spinal stenosis.
Treatment For Atlanto-Axial Dislocation And Fracture
Conservative Treatment For Atlanto-Axial Dislocation And Fracture-
- Indications for Conservative Treatment-
- Fracture: Non-displaced and stable.
- Dislocation: Non-displaced and stable dislocation or Subluxation.
- Soft neck collar
Medications For Atlanto-Axial Dislocation And Fracture
- Acute and Chronic Pain-
- Muscle Spasm
- Muscle relaxants
- Skelaxin, Flexeril, Baclofen and Soma.
- Neurontin or Lyrica
Surgery for Atlanto-Axial Dislocation And Fracture
- Indication for Surgery
- Subluxation of atlanto-axial joint
- Dislocation: Partial or complete dislocation of Atlanto-axial joint
- Choice of Surgery-5
- Fracture reduction
- Fusion of the joint
Prognosis Of Atlanto-Axial Dislocation And Fracture
- Atlanto-Axial Joint Injury With Intact Spinal Cord-
- Complete recovery of numbness, paresthesia and weakness is observed in absence of spinal cord injury.
- Dystonia, torticollis and gait abnormality may correct following complete recovery and reduction of swelling of spinal cord.
- Chronic pain.
- Injury Associated With Spinal Cord Damage
- Prognosis often is not good.
- Patient may sustain permanent sensory and motor deficiency like numbness and weakness of muscles.
- Spinal cord injury may result in quadriplegia.
1. Atlantoaxial instability in acute odontoid fractures is associated with nonunion and mortality.
Evaniew N1, Yarascavitch B2, Madden K3, Ghert M4, Drew B4, Bhandari M5, Kwok D4.
Spine J. 2014 Mar 22. pii: S1529-9430(14)00303-9.
2. Traumatic posterior atlantoaxial dislocation without associated fracture and neurological deficit.
Zhen P1, Lan X, Yang LW.
Arch Orthop Trauma Surg. 2011 May;131(5):681-5.
3. Traumatic atlantoaxial dislocation with odontoid fracture: A case report.
Moreau PE1, Nguyen V, Atallah A, Kassab G, Thiong’o MW, Laporte C.
Orthop Traumatol Surg Res. 2012 Sep;98(5):613-7.
4. Analysis of predisposing factors in elderly people with Type II odontoid fracture.
Watanabe M1, Sakai D2, Yamamoto Y2, Nagai T2, Sato M2, Mochida J2.
Spine J. 2014 Jun 1;14(6):861-6. doi: 10.1016/j.spinee.2013.07.434. Epub 2013 Sep 20.
5. Atlanto-axial dislocation complicating a type II odontoid fracture. Reduction and final fixation.
Riouallon G1, Pascal-Moussellard H2.
Orthop Traumatol Surg Res. 2014 May;100(3):341-5.