Previously often referred to as atlantoaxial subluxation, rotational displacement in children is an old problem, but due to the limitations of past understanding and reliance on highly inaccurate radiographic diagnosis, clinicians often make errors in judgment, mostly overdiagnosis, and mistake some normal imaging manifestations for abnormalities. Therefore, it is necessary to strengthen the study of the etiology and epiphyseal development, pathogenesis, morbidity, diagnosis and staging, treatment methods and choices and new understanding of this disease. I. Etiology Spontaneous atlantoaxial displacement occurs in most children as a result of minor trauma or inflammation of the pharynx. Ligamentous relaxation and rupture secondary to upper respiratory tract infections, neck infections, minor trauma, postoperative cervicopharyngeal surgery, and rheumatoid disorders can lead to the disease.Down’s syndrome, posterior cranial fossa or upper cervical medulla spinal cord tumors and myxofibromas, spinal cavernous disease, Arnold-chiari malformation, seronegative spondyloarthropathies, progressive ossifying fibrous dysplasias, and mucopolysaccharidoses (types III and IV) can also occur, Buccal nerve paralysis can also lead to the disease. Atlantoaxial rotational displacement (AARD) can occur 2 weeks to 6 months after the onset of upper respiratory tract infection, tonsil or salivary gland surgery, retropharyngeal abscess, or osteomyelitis of upper cervical vertebrae, etc. The mechanism of AARD is presumed to be the expansion of atlantoaxial transverse ligament and atlantoaxial instability caused by inflammatory edema, instead of the original ligamentous laxity. AARD should be considered in children with recent upper respiratory tract infections, posterior pharyngeal wall or neck infections, history of (minor) trauma, pharyngeal surgery, and previous history of rheumatoid disorders, tuberculosis, etc. The typical posture of this disease is often described as the “robin’s feeding posture”: the head is tilted to one side, the chin is turned to the opposite side, and there is mild flexion of the neck. The head is tilted to one side and the chin is turned to the opposite side, while there is still a mild flexion of the neck. In the acute phase, the child refuses to actively turn the head, and passive rotation can cause significant pain, resulting in limited rotation in the contralateral direction of the trapezius. Tension in the sternocleidomastoid muscle on the side of the chin deviation may suggest a tendency to correct the deformity. When the deformity is fixed, the pain is relieved, but the tilt may persist with limited head movement. All suspected patients should be examined on C1-C2 open-axis and lateral X-rays of the upper cervical spine. C1-C2 open-axis radiographs of the AARD often show asymmetric morphology of the left and right atlantoaxial blocks, with unequal spacing from the median axis of the odontoid process; the atlantoaxial lateral blocks are not parallel to the facets of the facet joints of the atlantoaxial and pivot vertebrae, and the lateral blocks often protrude over the margins of the corresponding supraspinatus joint facets of the pivot vertebrae. In lateral radiographs, especially in cervical flexion and extension, the distance between the cortex of the posterior margin of the anterior atlantoaxial tubercle and the cortex of the anterior margin of the odontoid process (ADI) should be observed, and a distance of more than 5 mm is clinically significant. Lateral and open orthopedic radiographs of the upper cervical spine are often of poor quality and difficult to distinguish from positional artifacts because of limited neck motion and the difficulty for the child to cooperate because of pain. AARD should be diagnosed when there is no pathology on x-ray and the clinical examination is positive (i.e., the signs do not match the x-ray), and the soft tissues of the posterior pharyngeal wall can be visualized on lateral cervical x-rays to assist in the diagnosis.Wholey suggests that the mean retropharyngeal clearance in children under 15 years of age is 3.5 mm and the mean posterior tracheal clearance is 7.9 mm and recommends that children be screened for AARD when the posterior pharyngeal clearance is greater than 7 mm and the posterior tracheal clearance is greater than 22 mm. It is recommended that if the retropharyngeal gap exceeds 7 mm and the retrotracheal gap exceeds 22 mm, then the patient should be examined for AARD. Dynamic CT scanning with extreme head rotation to both sides can clearly show the rotational restriction of atlantoaxial spine relative to the pivot vertebrae in children with AARD, which is a good means of detecting AARD. Static and dynamic functional CT is not only an important means of diagnosing AARD, but also helps to determine the prognosis of the injury; MRI can observe the relationship between the odontoid process and the atlantoaxial vertebral masses in detail and successfully because it can perform coronal scanning without the need for the patient to open his mouth or tilt his head back; it can also obtain the ADI value in the sagittal plane, and observe the signal of atlantoaxial transverse ligaments with or without weakening in the transverse plane, so it provides a strong support for the diagnosis of AARD. Therefore, it provides strong support for the diagnosis of AARD. For a long time, because of the limited understanding of the pathologic anatomy of atlantoaxial rotational displacement, there is a confusion in naming: rotational dislocation, rotational deformity, rotational subluxation, rotational fixation and spontaneous congestive dislocation, etc. The name “atlantoaxial rotational dislocation” is used in this study. The term “atlantoaxial rotational subluxation” is often used to describe acquired cervical dystocia in children. However, in addition to subluxation, there is often an anterior displacement of the atlantoaxial vertebrae relative to the cardinal vertebrae, and it is this anterior displacement that leads to a decrease in the Steel safety zone and a tendency for the cervical spinal cord to be compressed. Therefore, the term “subluxation” tends to paralyze the doctor and does not focus on the nerve injury, and the term “rotational displacement” is more appropriate and precise. In a few cases, the tilt-neck deformity may continue unabated, which should be called “atlantoaxial rotational fixation (AARF)” or “atlantoaxial fixation and displacement” more appropriately. Fielding proposed the famous Fielding-Hawkins classification: Type I: rotation, mild anterior displacement, ADI ≤ 3 mm; Type II: significant rotation, significant anterior displacement, ADI 3-5 mm, at this time the transverse atlantoaxial ligament has been ruptured; Type III: significant rotation, anterior displacement is very obvious, the ADI > 5 mm, when the ADI reaches 10-12 mm, all the atlantoatlantoaxial ligament are ruptured, at this time the C 1 is ruptured, and the C 1 is ruptured. When the ADI reaches 10-12 mm, all atlantoaxial ligaments are ruptured and C 1 and C 2 are highly unstable; Type IV: rotation with posterior subluxation. This type has been widely accepted and is still used. Early and accurate diagnosis and appropriate treatment are necessary, otherwise cervical instability or even cervical cord compression may occur. When the symptoms are mild, painkillers and soft foam cervical braces are recommended; when there is no anterior subluxation of the C1, immobilization should only be continued until the symptoms are relieved. Occipitomandibular sling traction can be given without manipulation before traction, and oral muscle relaxants and analgesics such as Valium and Benadryl can be given if necessary. When the active lateral rotation is the same bilaterally, the traction can be removed, and the child can be immobilized with a soft cervical brace until the cervical movement is completely restored, especially when the posterior extension movement is completely normal and the cervical spine has no abnormality in lateral flexion-extension X-rays. Levy emphasized the importance of posterior extension traction repositioning, otherwise clinical and radiographic signs of instability may persist. If there is anterior displacement of the atlas, the atlantoaxial joint should be followed closely because of the possibility of persistent atlantoaxial instability.Wong believes that bioelectrical feedback to the cervical spine is helpful in relieving muscle spasm after neck trauma. If there is no atlantoaxial transverse ligament tear, it can be treated conservatively; if there is a transverse ligament tear, the AARD can be fused if conservative treatment is ineffective; if there is an anterior or posterior atlantoaxial subluxation, it should be treated surgically, regardless of whether it is rotated or not. In rare cases of atlantoaxial fixation, severe neurologic injury can occur when accompanied by anterior displacement of the C1. Atlantoaxial fusion should be performed when: (1) there is nerve damage; (2) there is significant anterior displacement of C1; (3) the deformity has been in place for more than 3 months and conservative treatment has failed; and (4) the deformity has recurred after at least 6 weeks of conservative immobilization. Pang et al. prospectively analyzed 29 patients with AARF and gave the following recommendations: (1) All patients with acute and subacute AARF should be treated with maxillo-occipital band traction, and once reset, the brace should be immobilized for 3 months. (2) For chronic type III patients, maxillo-occipital band traction should also be performed first, and after repositioning, the patient should be immobilized in a brace. If recurrence occurs during fixation, cranial traction and Halo brace fixation should be performed. (3) In chronic type II patients, maxillo-occipital band traction should also be performed first, and Halo brace fixation should be used directly after repositioning in consideration of the high recurrence rate. (4) Because of the poor prognosis, high recurrence rate, and long treatment time of chronic type I patients, cranial traction should be used directly, and Halo bracket fixation should be used for 3 months after repositioning. (5) After the first recurrence, the post-recovery classification should be analyzed. Type III patients can be treated with braces, while type I and II patients should be fixed with cranial traction and Halo stenting. (6) All patients with a second recurrence are defined as recurrent AARF, and should be fixed with cranial traction and Halo stenting in acute and subacute patients, and surgical fusion in chronic patients. (7) Surgical fusion is recommended for all recurrences that occur during Halo use or after removal of the Halo stent. (8) Surgical fusion is recommended for all patients who cannot be reset after cranial traction.