Atlantoaxial joint instability

Introduction The atlantoaxial joint is a general term for the connection between the first cervical vertebrae and the second cervical vertebrae, including three independent joints, namely two atlantoaxial joints and one atlantoaxial joint. There is abnormal development in the neck of the occipital neck. After trauma, the acute dislocation of the atlantoaxial joint is more likely to occur than normal. In most cases, atlantoaxial instability occurs gradually after adolescence. Adult cases are often secondary to rheumatoid arthritis , and children are often secondary to infection in the neck. Dislocation caused by instability of atlantoaxial joint is divided into traumatic dislocation, congenital malformation dislocation, spontaneous dislocation and pathological dislocation.

Cause

First, traumatic dislocation.

1. Combined with odontoid fractures: that is, the atlas is accompanied by a odontoid fracture. From the posterior superior angle of the vertebral body or the posterior edge of the fracture line, the leading edge of the posterior arch of the atlas is measured. This distance is the effective space occupied by the spinal cord. Based on this, the stenosis of the buffer gap and the compression of the spinal cord can be estimated.

2. Simple anterior dislocation of the atlas: no dislocation of the atlantoaxial joint without odontoid fracture, there must be extensive damage of the ligament between the atlantoaxial joints. Due to the presence of odontoid process, the spinal cord is sandwiched between the odontoid process and the posterior arch of the atlas, which is more vulnerable.

Second, congenital malformation dislocation. There is abnormal development in the neck of the occipital neck. After trauma, the acute dislocation of the atlantoaxial joint is more likely to occur than normal. In most cases, atlantoaxial instability occurs gradually after adolescence. Common two kinds: (1) segmental obstacles, manifested as occipital and atlantoaxial fusion into the neck 2 ~ 3 vertebral body fusion; (2) odontoid hypoplasia.

Third, spontaneous dislocation. Adult cases are often secondary to rheumatoid arthritis, and children are often secondary to infection in the neck. The essence of atlantoaxial rotation fixation is old dislocation. Fielding (1977) refers to the atlantoaxial rotatory subluxation state that occurs after spontaneous or mild trauma. Later (1983) he also called the rotatory shift.

Fourth, pathological dislocation. Also for the slow dislocation, the difference from spontaneous dislocation is that there are osteoporotic lesions of the atlas and/or the atlas. In China, atlantoaxial tuberculosis is more common, and occasionally in atlantoaxial tumor or osteomyelitis.

an examination

Related inspection

CT scan of mammography

A clear history of trauma can be distinguished from subluxation caused by inflammation. Except for other parts of the upper cervical vertebrae, X-rays must be taken. The main feature of the X-ray position is that the distance between the two vertebral odontoid and the lateral vertebral vertebral is asymmetrical, but the cooperation between the two is not good, the projection position may be skewed, causing the gap between the two to be abnormal, or not satisfactory. The area is anatomically structured. If necessary, take more shots to eliminate misdiagnosis caused by improper projection position. Lateral radiographs can clearly show the change in distance between the odontoid and atlantoaxial arch. Under normal circumstances, it is within 3mm. CT scan if necessary, identification of atlas vertebral arch fracture and upper cervical deformity. Attention should be paid to severe old subluxation. It is characterized by torticollis and restricted movement, and pain during neck activity, which can lead to facial asymmetry. The appearance of the torticollis can cause the contralateral sternocleidomastoid tendon. Secondly, the transverse ligament is a soft tissue: it cannot be developed in the general X-ray, and its damage should be judged by indirect images. The midpoint to odontoid distance (ADI) of the anterior arch of the atlas is useful.

(1) Increased molar spacing: The lateral posterior segment shows the distance between the posterior border of the anterior arch of the atlas and the corresponding point of the odontoid. The normal adult and the child are 3mm and 4mm respectively; if the adult molar distance is between 3mm and 5mm, Often prompted to have a transverse ligament tear. If the molar distance is 5mm ~ 10mm, it indicates that the transverse ligament has a fracture and some auxiliary ligament tear; for example, 10mm ~ 12mm proves that all ligaments are broken.

(2) occipital neck extension and flexion lateral position: showing the anterior arch and dentate process of the atlas vertebral arch with a V-shaped gap, suggesting partial tearing of the fibers below the transverse ligament, so that the atlantoaxial joint is unbroken The fiber bundle acts as a fulcrum. It is shown that the partial separation of the caries gap is V-shaped.

(3) The flank and extension of the occipital neck showed a posterior instability of the atlas and was diagnosed as ligament injury.

Differential diagnosis

A clear history of trauma can be distinguished from subluxation caused by inflammation. Except for other parts of the upper cervical vertebrae, X-rays must be taken. The main feature of the X-ray position is that the distance between the two vertebral odontoid and the lateral vertebral vertebral is asymmetrical, but the cooperation between the two is not good, the projection position may be skewed, causing the gap between the two to be abnormal, or not satisfactory. The area is anatomically structured. If necessary, take more shots to eliminate misdiagnosis caused by improper projection position. Cervical spondylosis: manifested as cervical disc degeneration itself and a series of secondary pathological changes, such as vertebral instability, loosening; nucleus pulposus protruding or prolapse; spur formation; ligament hypertrophy and secondary spinal stenosis, etc. Or oppresses adjacent nerve roots, spinal cord, vertebral artery and cervical sympathetic nerves, and causes a variety of symptoms and signs of the syndrome.

A sprained neck is generally called a "slowing pillow." Because of the wind and cold invading the back of the item, the blood stasis and qi stagnation, the meridian is not comfortable; or the neck is not properly placed when sleeping; or the head is violently twisted and other causes of neck pain, called neck sprain.

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