Pathoanatomy, biomechanics, and treatment of upper cervical ligamentous instability: A literature review

Abstract

Background Cervical spine instability broadly refers to compromise of the articular congruity. It can be stratified according to spinal level, functional compromise, and mechanism of instability. Conventional wisdom advocates for use of bracing and physical therapy with only a subset of patients proceeding to obtain surgical treatment. Objective The purpose of this review article is to summarize the current state of knowledge on upper cervical ligamentous instability. Methods The literature search was performed in Mendeley. Search fields were varied until redundant. All articles were screened by title and abstract and a preliminary decision to include an article was made. The full-text screening was performed on the selected articles. Any question regarding the inclusion of an article was discussed by 3 authors until an agreement was reached. Results Many articles report on the etiological factors including ligamentous laxity, traumatic injury, syndrome instability, iatrogenic instability, congenital, and inflammatory causes. A few recent studies elucidate new findings regarding pathoanatomy through the use of finite element analysis. A few articles demonstrate the diagnosis and show that radiographs alone have a low diagnostic rate and that functional MRI may be able to better quantify instability. Conservative treatment has been described, but there are no outcome studies in the literature. Surgical treatment has been described in many different populations with good radiologic and clinical outcomes. Recently the use of preoperative 3D CT reconstruction has been described with radiographic and immediate postoperative patient-reported outcomes. Conclusion The presentation of upper cervical spinal instability can be asymptomatic, symptoms of isolated instability, symptoms of nerve irritation, vertebrobasilar insufficiency, or severe neurologic compromise. 3D fine element analysis models and motion-capture systems have the potential to increase our understanding of the pathoanatomic cascade in both traumatic and non-traumatic cases of upper cervical spinal instability. A few modalities on the horizon could increase diagnostic potential. More efforts are needed regarding the use of fine element analysis in understanding the pathoanatomic cascade, the long-term outcomes of children over a spectrum of syndromic causes, and the potential of preoperative virtual simulation to improve surgical outcomes.

Diffuse idiopathic skeletal hyperostosis: A functional enemy of vertebral stability – Case series and surgical consideration of craniovertebral junction involvement

“…Chronic instability can lead to a permanent lengthening of a ligament over time, which causes abnormal joint loads, chronic subluxation, and subsequent worsening of instability. [ 16 ] It has been postulated that instability itself may act as primum movens for several conditions such as cervical spondylosis, OPLL, cervical kyphotic and scoliotic deformities, fibrous abnormal proliferation, Chiari malformation, syringomyelia, and basilar invagination. [ 17 18 19 20 21 22 ] According to these premises, every condition causing subaxial spine stiffness may worsen CVJ instability.…”

Unveiling the Vital Role of Critical Neck Protection Devices for Motorcycle Riders: A Review

“…7,9 Whiplash injuries often happen during low-velocity rear-end collisions as the cervical spine experiences sudden hyperextension followed by hyperflexion, or hyper-lateral flexion. 7,10 This mechanism of action can lead to neck instabilities within the craniocervical junction region, including atlantoaxial instability and occipitocervical dislocations. Atlantoaxial instability includes rotatory instability, C1-C2 horizontal displacement and distraction injuries, and atlanto-dens instability.…”

“…Atlantoaxial instability includes rotatory instability, C1-C2 horizontal displacement and distraction injuries, and atlanto-dens instability. 10 Occipitocervical instabilities are caused by due disruption of ligaments between the occiput and C1 vertebrae. 7,10 Whiplash injuries are classified on a whiplash-associated disorder (WAD) 1-5 scale based on the severity of all WAD 1 injuries including those of the often-injured anterior longitudinal ligament and WAD 2 including dislocated or unilateral locked facets.…”

“…10 Occipitocervical instabilities are caused by due disruption of ligaments between the occiput and C1 vertebrae. 7,10 Whiplash injuries are classified on a whiplash-associated disorder (WAD) 1-5 scale based on the severity of all WAD 1 injuries including those of the often-injured anterior longitudinal ligament and WAD 2 including dislocated or unilateral locked facets. 10 Riders are at greater risk of suffering one of these injuries in accidents involving a topside/highside collision or a head-leading collision.…”

“…7,10 Whiplash injuries are classified on a whiplash-associated disorder (WAD) 1-5 scale based on the severity of all WAD 1 injuries including those of the often-injured anterior longitudinal ligament and WAD 2 including dislocated or unilateral locked facets. 10 Riders are at greater risk of suffering one of these injuries in accidents involving a topside/highside collision or a head-leading collision. A topside collision occurs when the rider flips over the handlebars, while a highside collision occurs when the rider is thrown opposite the turn direction due to improper correction.…”