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.
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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.