Cervical subluxation mostly occurs in adults and is rare in children. It is an unstable injury of the cervical spine. Due to its subtle nature, cervical subluxation is prone to missed diagnosis or misdiagnosis.

bubble_chart Pathogenesis

When the cervical spine is subjected to flexion force or a vertically compressive force while in a flexed position, the anterior compressive stress on the affected vertebral body increases, while the posterior structures of the cervical spine experience tensile stress. During the forward flexion movement of the vertebral body, the instantaneous center of rotation of adjacent vertebrae is located slightly posterior to the center of the intervertebral disc. At this point, the anterior part of the vertebral body serves as the fulcrum, and the tensile stress side involves the joint capsule, interspinous ligament, and ligamentum flavum. The continuous action of bending and compressive forces can lead to two scenarios: if the compressive force is significant, it may cause anterior collapse of the vertebral body, and in some cases, posterior herniation of the cervical intervertebral disc. If the force is insufficient to cause a vertebral fracture, the joint capsule and ligaments on the tensile side may tear, with severe cases also damaging the posterior longitudinal ligament. Persistent external force can cause the two joints of the superior cervical vertebra to slide forward and separate. This forward sliding of the posterior facet joints is related to the pathological basis of the intervertebral disc. If the intervertebral disc functions well during force application, the instantaneous center of rotation remains unchanged, and the external force on the posterior facets is primarily tensile. Dislocation only occurs if the joint capsule tears. When the intervertebral disc degenerates, its height decreases, and the surrounding annulus fibrosus and ligaments become lax, creating potential instability in the vertebral segment. During force application, vertebral displacement occurs, or the instantaneous center of rotation shifts posteriorly or inferiorly. The bending motion of the cervical spine generates significant shear forces between the posterior facet joints, causing them to slide against each other, leading to ligament and joint capsule tears. Injury to the posterior longitudinal ligament is also one of the causes of impaired intervertebral disc function. After the external force ceases, the contraction of neck muscles may pull a partially dislocated joint back into place. However, some cases remain partially dislocated due to joint capsule entrapment or obstruction by small fracture fragments.

Analysis of the injury mechanism indicates that any traumatic cervical spine subluxation involves cervical disc dysfunction and cervical instability. Secondly, the posterior soft tissues, specifically the posterior ligamentous complex, exhibit extensive tearing, hemorrhage, and hematoma. These are common pathological changes in all flexion injuries. Capsular tears lead to facet joint laxity and instability. There may also be associated annulus fibrosus rupture and posterior longitudinal ligament tearing or separation. Nearly one-third to one-half of torn ligaments do not heal. If adequate immobilization is not provided post-injury to allow soft tissue repair, instability may persist, resulting in "delayed cervical spine instability," particularly in middle-aged and elderly patients. In these cases, pre-existing degeneration of the disc-ligament structures means that even minor traumatic forces, if left untreated, can lead to a higher incidence of late-stage (third-stage) cervical spine instability.

bubble_chart Clinical Manifestations

The symptoms of anterior cervical semi-dislocation are relatively mild, mainly localized, such as fatigue in the neck, local pain, soreness, lack of strength; limited flexion, extension, and rotation of the head and neck; muscular rigidity in the neck, with the head and neck appearing forward-tilted and feeling stiff; swelling and tenderness in the spinous process and interspinous space of the injured segment, and possible tenderness on the anterior side of the vertebrae.

Neurological symptoms are relatively rare and, even when present, are usually not severe, sometimes manifesting as signs and symptoms of nerve root irritation. However, the true significance of cervical semi-dislocation lies in its tendency to cause future instability and accelerate degeneration of the intervertebral discs. If this instability between vertebral bodies persists, according to Wolff's law, the vertebrae above and below the intervertebral disc will inevitably undergo osteophyte formation to increase the contact area between the vertebral bodies and enhance stability. Osteophyte formation can lead to a reduction in the sagittal diameter of the spinal canal, and in severe cases, compress the spinal cord, causing chronic injury. Its clinical manifestations are similar to those of cervical spondylosis.

AD

TCM's treatment of atopic dermatitis is more comprehensive, fundamental, non-toxic and effective than Western medicine's symptomatic treatment

In the acute phase, lateral X-ray films may show no abnormal signs. If the small joints remain in a semi-dislocation state, the lateral film may reveal abnormal joint alignment. Sometimes, dynamic flexion-extension radiographs can be used to demonstrate instability in the injured segment. Some recommend that when taking flexion-extension films, the patient should lie prone or supine on a curved support, and the diagnosis can be confirmed once vertebral displacement is detected.

In addition to X-ray films, some use moiré topography to observe and assess the presence of cervical spine instability.

bubble_chart Treatment Measures

Traction Therapy Traction can usually achieve reduction, but skull traction is unnecessary, as occipitomandibular traction is sufficient for reduction. During traction, the head should be in a neutral position with a weight of 2–3 kg. After radiographic confirmation of reduction, continuous traction should be maintained for 3 weeks. Due to the high tendency for severe instability post-reduction, re-dislocation is very likely. Therefore, after reduction, a head-neck-thorax gypsum cast should be applied for 2–3 months. After removing the gypsum, a cervical brace should be used for a period of time. Manual reduction is not recommended; if it must be performed, caution is required to avoid aggravating the injury.

Surgical Treatment Surgery is not recommended in the acute phase. If instability of the injured segment persists in the late stage [third stage] or is accompanied by delayed spinal cord or nerve root compression, surgical treatment is indicated. An anterior cervical approach should be taken to perform discectomy, decompression, and bone graft fusion. If spinal cord compression is present, extensive decompression and bone graft fixation should be performed.