|SYMPOSIUM: CERVICAL SPINE TRAUMA
|Year : 2022 | Volume
| Issue : 1 | Page : 24-38
Approach and considerations for surgery in subaxial cervical spine injury: A narrative review
K S Sri Vijay Anand, Ajoy Prasad Shetty, S Rajasekaran
Department of Spine Surgery, Ganga Hospital, Coimbatore, Tamil Nadu, India
|Date of Submission||01-May-2021|
|Date of Decision||10-Jun-2021|
|Date of Acceptance||21-Jun-2021|
|Date of Web Publication||02-Feb-2022|
Department of Spine Surgery, Ganga Hospital, 313, Mettupalayam Road, Coimbatore, Tamil Nadu.
Source of Support: None, Conflict of Interest: None
Subaxial cervical spine injuries are common and encompass a spectrum of injuries ranging from a minor ligamentous sprain to fracture dislocation with spinal cord injury. These injuries are often missed in the initial evaluation, and a high index of suspicion is needed to evaluate and diagnose these injuries, which otherwise could lead to spinal cord injury. Computed tomography scans are the gold standard in the evaluation of fractures as plain radiographs have limited sensitivity. Magnetic resonance imaging (MRI) is necessary to identify injury to the disco-ligamentous complex and to assess cord injury. The principles of the treatment of cervical spine injuries include early immobilization to prevent secondary neurological injury, achieving alignment by reduction and stabilization of the unstable injured segment and decompression of the cord in the presence of cord injury. Owing to a broad spectrum of injuries, there is no unified approach, and the management plan depends on the morphology of injury, the extent of structures damaged, and the presence of neurological impairment. Various classifications grade and help assess the severity of the injury. Minor injuries are conservatively managed with cervical orthoses, and unstable injuries require stabilization either anterior, posterior, or combined approaches, depending on the injury morphology. Controversy exists over the safety of closed reduction in facetal subluxations, need for pre-reduction MRI, and the ideal approach for each injury. This review presents the current evidence and guidelines on the management of subaxial cervical spine injuries.
Keywords: Facetal subluxations, fracture dislocation, management, subaxial cervical spine
|How to cite this article:|
Vijay Anand K S, Shetty AP, Rajasekaran S. Approach and considerations for surgery in subaxial cervical spine injury: A narrative review. Indian Spine J 2022;5:24-38
|How to cite this URL:|
Vijay Anand K S, Shetty AP, Rajasekaran S. Approach and considerations for surgery in subaxial cervical spine injury: A narrative review. Indian Spine J [serial online] 2022 [cited 2022 May 25];5:24-38. Available from: https://www.isjonline.com/text.asp?2022/5/1/24/337144
| Introduction|| |
Subaxial cervical spine fractures account for two-thirds of all fractures and three-fourths of all dislocations. The motion provided by its unique anatomy predisposes to different injury patterns by a combination of force vectors and mechanisms. This occurrence of multiple fracture patterns has made the classification, grouping, and nomenclature of these fractures difficult. Various classification systems and algorithms for management are available, but none has been universally accepted or without shortcomings. The management for these fractures has lacked consensus concerning the decision to operate, choice of surgical approach, and instrumentation. Literature is replete with case series and comparative studies of small cohorts. However, studies with level 1 or level 2 evidence have been lacking. With this in the background, we did a comprehensive search and a narrative review of literature on subaxial cervical spine fractures and management options and presented our updated evidence-based recommendations in this review.
| Materials and Methods|| |
Using the following Mesh terms “subaxial cervical spine fractures,” “management,” “facetal subluxation” as Mesh headings and keywords, a comprehensive search was done in PubMed database and Google Scholar on March 21, 2021. Only articles in English with full text were included. The search resulted in a total of 9450 articles initially. Articles not pertaining to the subaxial cervical spine, not related to the current topic of interest, and duplicates were excluded. All original articles pertaining to the subject of interest and additional articles from recent reviews were handpicked and included in this review, resulting in 184 studies.
| Modes and Mechanism of Injury|| |
Among the spinal injuries, two-thirds of all fractures and three-fourth of all dislocations are concentrated in the subaxial cervical spine, with 39% of injuries located in the sixth or seventh cervical vertebrae. The most common mode of cervical spine injury is vehicular motor accidents, falls, violence, sports injuries, and the fall of a heavy object on the head.,, Regional variations in the mode of injury exist, with falls more common in middle- and low-income countries, whereas vehicular motor accidents and sports injuries are more common in developed countries. Even a trivial trauma could cause a fracture in an ankylosed spine, and a high index of suspicion is needed. The injury mechanism and the resultant vector forces largely determine the anatomical pattern and type of vertebral fractures. Three column injuries of the subaxial cervical spine can be completely bony, completely discoligamentous, or a combination of the two. Based on the mechanism of injury, Allen et al. classified the fractures into six types: compressive flexion (21.8%), vertical compression (8.4%), distractive flexion (36.9%), compressive extension (24.2%), distractive extension (5.4%), and lateral flexion (3.0%).
| Acute Care|| |
The acute management of cervical spine injury includes three phases: pre-hospital care, acute in-hospital care, and definitive treatment. The management of patients with cervical spine injuries begins at the site of the injury itself. Around 3–25% of spinal cord injury occurs after the initial impact, and therefore immobilizing the spine is the first step in management. The cervical spine should be immobilized in a neutral position with a hard cervical collar over the spine board with tapes applied over the forehead, chest, and extremities. A primary survey should be done as per the advanced trauma life support protocol in all patients, which includes (1) clearance of the airway, (2) support of breathing, (3) maintenance of circulation, (4) assessment of disability, and (5) exposure. The vital parameters should be stabilized before proceeding to a secondary survey. It is not uncommon for spinal cord injury patients to present with neurogenic shock, characterized by hypotension, bradycardia, and hypothermia, and it is crucial to differentiate it from hemodynamic shock, which has hypotension and tachycardia, especially in a polytrauma scenario. While the hemodynamic shock is managed with volume replacement and blood transfusion, the neurogenic shock is managed with inotropics (dopamine or dobutamine) to maintain blood pressure and atropine for bradycardia. Maintenance of perfusion pressure and oxygenation is vital to reduce the risk of secondary spinal cord injury.
Once the patient is hemodynamically stabilized, a detailed secondary survey is performed to identify the mechanism of injury and the presence of multiple injuries. Clinical examination has limited sensitivity (77%) in identifying cervical spine injury, and up to 30% of such injuries can be missed initially. A thorough clinical examination evaluating point tenderness, palpable step-off, restricted range of motion, and presence of neurological deficit could indicate an underlying cervical spine injury. In this context, the NEXUS criteria and Canadian C spine rule help identify patients with significant cervical spine injuries who may benefit from further radiological imaging.
Evaluation to rule out other injuries must be performed, as around 47% of individuals will have associated injuries. The presence of associated head injury (35%), chest injury (24%), and injury to extremities (28%) are common and should be evaluated thoroughly., Non-contiguous concomitant spinal injuries can occur in 15–20% of the individuals, and hence entire spine should be evaluated., Vertebral artery injuries are a common co-occurrence in cervical spine injuries with a reported 13–39% incidence. Flexion-distraction and flexion-compression mechanisms are prone for such injuries in which the artery is injured either by distraction or compression. Most of these injuries are unilateral, asymptomatic, and incidentally noticed during radiological evaluation. However, symptoms such as dizziness, syncope, dysarthria, dysphagia, diplopia, and tinnitus can occur due to vertebra-basilar insufficiency as late as 3 months, and further imaging such as magnetic resonance angiography is warranted in such symptomatic patients.
| Diagnostic Workup|| |
Once the patient is adequately resuscitated, patients with suspected cervical spine injury should undergo diagnostic imaging. Radiographs of the cervical spine are the preliminary investigation in patients with a suspected cervical spine injury. An antero-posterior, lateral, and open-mouth views are the standard views taken. The radiographs have to be checked for adequacy; the cervicothoracic and occipitocervical junction should be visible. About 17% of cervical spine injuries occur at the cervicothoracic junction, and inadequate radiographs increase the likelihood of missed injuries. The radiographs have to be assessed for overall alignment, decreased disc space, facet subluxation, and widening of interspinous distance. The sensitivity of plain radiographs in detecting fractures and ligamentous injuries of the cervical spine is only 30–60%., Dynamic flexion-extension views are difficult to obtain and best avoided in acute trauma scenarios., Computed tomograms with their increased sensitivity (99%), specificity (100%), and speed have become the investigation of choice in cervical spine injuries., They help in the early clearance of the cervical spine in patients without neurological deficit and in comatose or intoxicated patients. The limitation of CT scan is its inability to identify pure ligamentous injuries. However, these injuries are seldom unstable at initial presentation or follow-up. Magnetic resonance imaging (MRI) provides excellent visualization and has high sensitivity in detecting injuries of disco-ligamentous complex (DLC). However, their specificity is low; therefore, careful interpretation is warranted to avoid unnecessary surgeries. Pourtaheri et al. evaluated the usefulness of MRI and found that patients with age more than 60, obtunded, cervical spondylosis, polytrauma, neurological deficit are likely to have clinical findings on MRI that alter the management. However, the majority of changes in the treatment plan were due to the presence of spinal cord injury (81%) rather than occult instability (19%).
| Management Protocols for Various Subaxial Spine Fractures|| |
The goals of management of cervical spine fractures include (1) reduction and restoration of alignment, (2) provide stability, (3) decompression of spinal cord to facilitate neurological recovery, and (4) early functional recovery and rehabilitation.
In the past, instrumentation was not available, and many of these injuries were conservatively managed with skull traction, postural reduction, or external orthoses with variable success. Even in the era of increased availability of surgical tools and imaging techniques, conservative measures have their role. They are used either as definitive management, initially before surgery, or as an adjunct to surgical management. Skull traction can be applied by Gardner-Well tongs or Halo ring. The latter is preferred if a halo vest is planned as a definitive treatment. Though compliance is poor and complications related to pin placement are common,,, it is helpful in the reduction of subluxations, maintaining alignment and preventing fusion in complex fractures. Caution is required in distraction injuries to prevent over distraction. A range of cervical braces is available for immobilization of the cervical spine. Soft cervical collars and Philadelphia collars offer comfort but offer little restraint to motion and are recommended only in stable injuries. Semirigid braces such as Aspen, Miami, and Malibu offer better stability. Poster braces and sterno-occipito-mandibular-immobilizer (SOMI) incorporate the upper torso into the construct and offer better subaxial cervical spine movement restriction. SOMI brace offers reasonable restriction of flexion (93%), lateral bending (66%), and rotation (66%) movements. However, it does not limit extension (42%) significantly. The most rigid immobilization is provided by Halo vest, which restricts all movements better than other available orthoses. However, it is relatively contraindicated in morbidly obese, frail elderly patients and ankylosing spondylitis. The efficiency of various cervical orthoses and the mean percentage of normal motion allowed by different cervical orthoses have been enumerated in [Table 1].,,,
The morphology and fracture pattern are the principal determinants of choice of management. Stable injuries such as compression fractures, avulsion injuries, fractures of posterior elements (lamina and spinous process), facetal sprains, stable burst fractures with intact neurology, and extension teardrop fractures can be managed conservatively with orthoses for 6–12 weeks (case example) [Figure 1]. However, in unstable injuries, the failure rates were higher. Closed reduction was successful in 64–91% of patients, and failure to achieve reduction was noted in 22.5% who presented late. In fracture dislocations, the orthoses failed to maintain the reduction in 7–56% of the patients. Overall, 30% of these had recurrent displacement or inadequate alignment during external immobilization. The risk factors for failed conservative management with traction or orthoses include vertebral compression of more than 40%, kyphosis >15%, or vertebral subluxation >20%.
|Figure 1: Avulsion injury of C5 vertebral body treated conservatively. Plain radiographs (A), CT scan (B), and MRI (C) show an avulsion injury of anterior-inferior corner of C5 vertebral body. Six-month follow-up radiographs show healing of fracture with no instability (D and E)|
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The main indications for surgery include (1) neurological deficit and (2) instability. However, the presence of neurodeficit alone is not an indication for surgery. While the progressive neurological deficit is an accepted indication, there is no consensus about the need for surgical decompression in incomplete injuries.
Instability is the primary indication for surgical stabilization; however, the definition of instability that warrants surgery is unclear. Various authors have suggested criteria for spinal instability. Panjabi et al. in 1978 evaluated the stability of the cervical spine under tension using cadaver models. They found that anterior injuries with greater than 3.3 mm translation at the disc level or greater than 3.8° of rotation in the sagittal plane were considered unstable. Similarly, posterior column injuries resulting in widening of interspinous space by more than 27 mm or more than 30° increase in angulation with the axial loading were considered unstable. They developed a scoring system based on the integrity of the anterior and posterior spinal elements, the extent of static and dynamic displacement, the presence of neurologic injury, and the anticipated physiologic loads to estimate instability [Table 2]. A score of more than 5 indicates instability and warrants surgical stabilization.
The spine trauma study group classified fractures based on injury morphology, the integrity of DLC, and neurodeficit and assigned scores for each [Table 3]. Injuries are classified into three patterns of injury morphology: (1) compression, (2) distraction, and (3) translation or rotation. The integrity of the DLC is directly proportional to spinal stability and is classified as disrupted, intact, or indeterminate. The third component of the Subaxial Cervical Spine Injury Classification (SLIC) system is neurologic injury. Treatment decision is made based on a summed up score of all three categories. A score of 5 or more is recommended for surgical management. Based on SLIC scores, Dvorak et al. proposed an algorithm for the management of subaxial cervical spine injuries. The common pattern of injuries and their management principles are discussed subsequently.
Compression or burst fractures
Compression or burst fractures are resultant of axial loading/vertical compression forces causing either or both endplate fractures. The DLC is intact in pure vertical compression forces without flexion. The retropulsed fragments can compress the cord and cause neurodeficit. As per SLIC scores, such fractures have a score ranging from 4 to 6; therefore, the most vital determinant for surgery would be the presence of neurodeficit. In the absence of neurodeficit or significant kyphosis, conservative management with cervical orthoses for 12 weeks can be recommended. Koivikko et al. compared conservative with anterior surgery and found better kyphosis correction, canal clearance, and neurological recovery with surgery in such injuries. An anterior corpectomy, decompression, and fusion with plating offer excellent results, and a posterior surgery in the absence of DLC injury is not required (case example) [Figure 2].,,,
|Figure 2: Burst fracture of C6 vertebral body. Plain radiographs (A) and CT scan (B) of C6 burst fracture treated by corpectomy, reconstruction with Harm’s cage, and anterior cervical plating (C)|
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Hyperextension injuries +/- avulsion injuries occur in elderly individuals with spondylotic spines. It comprises a spectrum of injuries with varying severity. As the violence increases, there is a sequential disruption of anterior ligaments, disc, posterior longitudinal ligament, DLC, and finally fracture of posterior elements. These injuries are often missed as the fracture is reduced in the supine position while obtaining radiographs. The presence of widening of disc space, increased anterior prevertebral soft tissue shadow, increased disc signal in MRI, and avulsion of anterior osteophytes provide a clue to the underlying injury. In mild injuries, there is avulsion of anterior osteophytes or anteroinferior corner of the vertebral body (extension teardrop). This is a stable injury with intact posterior longitudinal ligament, with an SLIC score of 3 (morphology-3, DLC-0, neurology-0), and can be conservatively managed. Transverse rupture of disc and ligaments can result in retrolisthesis of the proximal vertebrae and neurodeficit. This is an unstable injury with an SLIC score >5 (morphology-3, DLC-2, neurology-0–3); therefore, this needs stabilization in the form of anterior discectomy and fusion with plating to counteract the extension forces. Vaccaro et al. reviewed their series of 24 distraction-extension injuries and recommended type 1 injuries to be treated with an anterior cervical discectomy and fusion (case example) [Figure 3]. In type 2 injuries with displaced vertebrae, an initial posterior procedure to realign the vertebrae may be required before an anterior procedure. An antero-posterior stabilization to counteract the long lever arms is recommended in an ankylosed spine with hyperextension injuries.
|Figure 3: C5-C6 hyperextension injury. Plain radiographs (A), CT scan (B), and MRI (C) of C5-6 hyperextension injury treated by anterior cervical discectomy fusion and anterior cervical plating (D)|
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Facetal subluxations are flexion-distraction injuries, the commonest pattern of subaxial cervical spine injury (36.9%). This injury results from hyperflexion forces with a center of rotation anterior to the vertebral body. The posterior column fails in tension with sequential disruption of the posterior ligamentous complex, facet subluxation, and the anterior column’s compression.
Unilateral facet dislocations have up to 25% of vertebral body translation, and radiculopathy is the most common symptom due to impingement on a nerve root by the superior vertebrae’s inferior facet. Cord injury can occur in up to 10% of the individuals. Reduction of subluxated facets is necessary to restore normal anatomy, decompress neural elements, and promote healing. Rorabeck et al. reported that late pain occurs if allowed to heal in an unreduced position. The reduction can be achieved by manipulation under conscious sedation in operation theater or by traction using incremental weights. The closed reduction has been reported to be successful in 90% with minimal risk of neurological worsening., However, caution is needed during reduction as it may lead to potential neurological worsening. The SLIC score for facetal subluxations (morphology-3, DLC-2, neurology-0–4, total >5) recommends surgical intervention. In unifacetal subluxations, the literature evidence also favors operative management over conservative management as treatment failure, persistent pain, and neurological deterioration occur more frequently with conservative management.,
Role of MRI and timing in facetal subluxation
Controversy exists over closed vs. open reduction, safety of closed reduction, and requirement of MRI before attempting reduction.,, Around 50% of facet dislocations have concomitant disc herniation or disruption., Few authors have reported neurological deterioration due to migration of disc fragments during attempted reduction., However, later studies by Doran et al., Rizzolo et al., and Grant et al. showed that closed reduction did not increase the risk of neurological injury in the presence of cervical disc herniations. Besides, closed reduction was able to reduce the disc herniation as well. If MRI is available, the reduction should be attempted only after an MRI confirmation to rule out traumatic disc extrusion. However, in situations in which MRI is unavailable, reduction may be attempted cautiously in an alert and awake patient with severe neurological injury. In patients with intact neurology or intoxicated/comatose patients, the reduction can be attempted during surgery after discectomy.
Closed reduction technique
Skull traction is applied with Gardner-Wells tongs, and a rapid reduction is attempted with close monitoring. Axial traction is applied with 5 kg weight in 20–30° flexion to begin with. The weights are serially incremented (2 kg for every 10 min) and monitored with lateral radiographs. Once the facets are unlocked, the neck is taken into extension position, maintaining the traction. In unilateral facet dislocations, rotating the head 40° toward the side of dislocation helps achieve reduction. After confirmation of reduction, the traction weight can be decreased to a maintenance weight. Various authors have reported a successful reduction in up to 97.6% with traction without neurological deterioration., High failure rates (22.5–26%) in reduction were observed especially in late presentations. The presence of facet fractures also impedes closed reduction. In manipulation under anesthesia (MUA) technique, after skull tong is applied, traction is applied at 45° of flexion, and after the facets reduce the neck is extended. In unifacetal subluxation, after 45° of flexion, the head is rotated 45° away from the dislocated side while maintaining traction, and then the head is rotated to the same side of subluxation. The subluxation reduces with a clunk. The neck is then stabilized in an extension position. Various authors have reported success with MUA.,, However, it should be noted that manipulation technique can cause potential neurological worsening and therefore should be performed by an experienced person with caution, in the operating room conditions or intensive care units in which monitoring, resuscitation, and equipments are readily available.,, Lee et al. compared rapid reduction with traction and MUA and found that rapid reduction is safer than MUA and helpful in early neurological recovery. Various studies on closed and open reduction technique have been summarized in [Table 4].
|Table 4: Major studies on reduction technique in cervical facetal subluxation|
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Surgical options in facetal subluxations
The surgical options for unilateral or bilateral facet injuries include an anterior-only approach, posterior-only approach, and a combined anterior and posterior approach. The choice of approach depends on (1) severity of injury and structures disrupted, (2) the presence of anterior disc herniation, and (3) whether the dislocation is reducible from a single anterior or posterior approach alone. In the presence of a disc herniation, an anterior approach is preferred. Anterior surgery is safer and easier as dissection is done along tissue planes and reduces the risk of iatrogenic subluxation and neurological worsening due to prone positioning. After discectomy, a reduction maneuver is performed to reduce the subluxation. Various reduction techniques have been described. The common method employs placing divergent Caspar pins in both rostral and caudal vertebral body and distracting using distractors. Manual or blunt compression is applied to rostral vertebrae to aid in reduction. In unilateral facet dislocation, the Caspar pins are applied at an angle to each other in the coronal plane to facilitate rotation during reduction., Other modifications include using a blunt instrument as a lever to push the rostral vertebra backward, using a laminar spreader to distract, and using Caspar pins as joysticks. An interbody graft or cage is placed, and anterior cervical plating is done. Contouring the plate to lordosis and trapezoidal graft placement helps in achieving tight opposition of facet joints and adds to stability. Though claimed to be biomechanically inferior to posterior instrumentation, the utility of anterior surgery has been proven by many authors. Kasimatis et al. in their series of 74 patients with mixed injuries treated by anterior surgery achieved a fusion rate of 90%, with only three requiring revision. Reindl et al., in their series of 41 patients with facetal subluxation treated by anterior surgery, did not notice any instrumentation failure. Johnson et al. treated 81 patients with facetal injuries by anterior surgery alone and found loss of reduction in 13% of patients and reported that mechanical failure of flexion/distraction injuries should be high when associated with fractures of either the facets or of the endplate. The presence of facetal fracture, endplate fracture, and C6-7 level injury was identified as risk factors for loss of reduction. Kanna et al. treated 39 consecutive patients with facetal dislocation and fracture by anterior approach and found no implant failure. A recent systematic review evaluating anterior surgery for facet dislocations supports its efficacy and success with low complication and implant failure rates (case example) [Figure 4].
|Figure 4: C5-C6 bifacetal subluxation. Plain radiographs (A), CT scan (B), and MRI (C) of C5-C6 bifacetal subluxation treated by anterior cervical discectomy fusion and anterior cervical plating (D)|
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If not reducible by anterior approach or in the absence of disc herniation, a posterior approach, and stabilization by a rod, screw construct can be done. The posterior approach has the advantages of direct visualization and reducing dislocation and decompression of any bony fragment compressing the cord., Stabilization on the tension side of the spine offers superior biomechanical stability, especially in osteoporotic bones (case example) [Figure 5]. The surgical technique uses a blunt instrument to lever the dislocated vertebra’s inferior facet over the superior facet of the caudal one or by gradually applying distraction forces on the spinous process using a bone holding forceps. If irreducible, superior facets of the lower vertebra can be excised to aid in reduction. The posterior reduction can risk neurological deterioration in cases of anterior compressive lesions such as disc herniation and has been considered a contraindication. However, reports about the frequency of this deterioration after posterior open reduction are scarce. Abumi et al. treated 16 patients with traumatic disc herniation by posterior reduction technique without any neurological deterioration. Nakashima et al. in their series of 40 patients treated by a posterior approach did not notice any neurological deterioration. Though the incidence of dysphagia in posterior surgery (11%) is less when compared with anterior surgeries (61.5%), the wound complication rates are higher., The pedicle screw construct offers better biomechanical stability than the lateral mass screw-based construct, though technically challenging., Biomechanical studies comparing anterior cervical discectomy fusion and plating with anterior cervical discectomy and fusion with posterior transpedicular screw-rod construct reported that the latter offered superior stability. However, anterior cervical discectomy, fusion, and plating demonstrated higher stability than the intact spine in most loading modes, and with a brace, it could be effective for stabilizing bifacetal dislocations. There are no high-quality clinical studies in the literature comparing anterior and posterior surgery for cervical facet dislocations. A Cochrane review on this subject (low-quality evidence) found little difference in patient-related outcomes and neurological recovery between the approaches. Sagittal alignment was better achieved with the anterior approach; however, no difference in failure of instrumentation and infection was noted.
|Figure 5: C5-C6 facetal subluxation treated by posterior approach. Plain radiographs (A), CT scan (B), and MRI (C) of C5-C6 facetal subluxation. Follow-up radiographs show healing with posterior lateral mass screw fixation in situ (D)|
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Combined anterior–posterior approaches are beneficial in chronic injuries, cervical misalignment requiring osteotomy, in the presence of facet fractures or end plate fractures, severe osteoporosis, ankylosing spondylitis, and diffuse idiopathic skeletal hyperostosis. The combined approach provides the strongest fixation, increasing the fusion rate, although without the additional advantage for neurological recovery.,, Studies using different approaches and instrumentation have been summarized in [Table 5]. Another controversy was in choosing the instrumentation levels. Single-level arthrodesis has the advantage of decreasing the long-term adverse effects of fusion on adjacent segments and is deemed sufficient in both unifacetal (only anterior) and bifacetal subluxations (anterior and posterior). However, there is a need to extend the instrumentation to adjacent levels in the presence of facet fractures.
|Table 5: Major studies on cervical facetal dislocations using anterior, posterior, or combined approaches|
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Unilateral cervical facet fractures at a single level that involve more than 40% of the absolute height of the intact lateral mass or an absolute fracture height greater than 1 cm, obesity (weight >100 kg), comminution of fracture, presence of radiculopathy, higher BMI, listhesis of more than 2 mm, and greater initial displacement are at increased risk for failure with conservative management,, and therefore needs surgical stabilization. In a systematic review by Kepler et al. to evaluate the treatment modalities in isolated facet fractures without any other injury, it was found that open reduction (90.8%) than closed reduction (43.2%), operative management (94.9%) than conservative management (59.1%), and anterior (90.5%) or combined antero-posterior approach (72.7%) than posterior-only approach offer superior results (75.6%) (case example) [Figure 6].
|Figure 6: C4-C5 bilateral facet fracture. Plain radiographs (A) and CT scan (B) of C4-C5 bilateral facet fracture treated by anterior cervical discectomy fusion and anterior cervical plating (C)|
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Translation or rotational injuries
Translation injuries are the most severe injury pattern with subluxation of one vertebrae over the other, either as a pure translation or with rotational component around the facet. These fractures have a varying degree of posterior element fractures, including spinous process, lamina, or lateral mass in association with vertebral body fracture of a varying pattern (endplate compression, burst, coronal, or sagittal split). They are inherently unstable with a SLIC score of >6 (morphology-4, DLC-2, neurology-0–4) and need surgical stabilization. There are three common patterns seen within this group: (1) facet fracture dislocation with endplate compression, (2) facet fracture dislocation with a burst or teardrop fracture of the vertebral body, and (3) facet fracture dislocation without vertebral body fractures. Facet-fracture dislocation without vertebral body fracture or endplate compression fracture can be treated by posterior stabilization alone. In the presence of vertebral body burst fracture or teardrop fracture with facet fracture dislocation, there is a significant posterior element disruption along with retrolisthesis of the vertebral body; therefore, a 360° anterior and posterior reconstruction is recommended (case example) [Figure 7].,,
|Figure 7: C6-C7 bifacetal fracture dislocation. Plain radiographs (A), CT scan (B), and MRI (C) of C6-C7 bifacetal fracture dislocation treated by combined anterior and posterior approaches|
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Fractures in ankylosed spine
Subaxial cervical spine is the most common location of the fracture in patients with ankylosing spondylitis. They are three column injuries that are potentially unstable with a high incidence of neurological deficit and therefore warrant surgical stabilization. The presence of long lever arms, osteopenia, and kyphosis makes surgery challenging. The choice of surgical approach would be a long posterior stabilization or a combined anterior-posterior stabilization to counteract the long lever arms. The readers are encouraged to refer to an earlier focussed issue on this type of fracture.
AO spine classification-based treatment recommendations
The recent AO spine classification for subaxial cervical spine injury is based on the injury mechanisms and helps in decision-making. It is broadly categorized into three types: (1) Type A: compression injuries (injuries with intact tension band), (2)Type B: distraction injuries (tension band injuries without translation), and (3)Type C: translational injuries. It has subtypes and six modifiers. The treatment recommendations made by the spine section of the German Society for Orthopaedics and Trauma (DGOU) based on AO spine classification are helpful and are summarized in [Table 6].
|Table 6: Recommendations by the spine section of the German Society for Orthopaedics and Trauma (DGOU) based on AO spine classification|
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| Conclusion|| |
Subaxial cervical spine injuries are common injuries that are frequently missed. It includes a spectrum of injuries with a heterogenous nomenclature. Early diagnosis and intervention are needed to prevent secondary neurological deterioration in unstable injuries. The management of subaxial cervical spine fractures depends on the extent of injury severity, and the ideal treatment and the approach for many of these injuries are debatable. The SLIC and AO spine classifications are helpful in decision-making.
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]