Anterior Flexion-distraction Technique for Reducing Cervical Facet Dislocations

INTRODUCTION Traumatic dislocations of cervical spine are a severe injury, most commonly caused by road traffic accidents. Subaxial cervical facetal subluxations occur due to hyperflexion-distraction injury and involve both the anterior and posterior columns.[1] Subluxations can be unilateral or bilateral. Unilateral facet dislocations occur when there is an added rotation injury in addition to flexion distraction. Bilateral facet dislocations are usually associated with a higher incidence of neurological injury compared to a unilateral facet dislocation.[1] In 1982, Allen et al. put forward the classification of cervical spine fractures and dislocations based on the biomechanics of cervical spine injury.[2] They classified facet dislocations as a flexion-distraction injury. In 2007, Vaccaro et al. published the new Subaxial Cervical Spine Injury Classification System (SLIC), which included injury pattern, severity of injury, and neurological status to prognosticate and manage the entity.[3] In 2016, the AO spine organization in association with Vaccaro et al., reached a consensus and put forward a new classification system of cervical spine fractures, merging the SLIC with the traditional ABCD (A = Absent injury, B = Bony lesion, C = Combined bony and ligamentous, D = Disc or ligamentous injury) classification and took into consideration, the neurological injury and presence of specific modifiers such as posterior ligamentous complex (PLC) injury and associated disc herniations.[3] Initial management and resuscitation should be based on Advanced Trauma Life Support protocol.[4] Assessment tools such as Canadian C-spine rules or the National Emergency X-Radiography Utilization Study are well accepted worldwide.[5] The most used tool is the International Standards for Neurological Classification of Spinal Cord Injury, commonly referred to as the American Spinal Injury Association (ASIA) Exam, developed by the ASIA.[6] A good plain cervical spine radiograph will show the degrees of displacement of the vertebral body. The cervical spine computed tomography (CT) scan is recommended in the initial assessment and further management of facetal subluxations. The British Orthopaedic Association Standards for Trauma and Orthopaedics in England recommended a thin-slice (2–3 mm) helical CT scan from the base of the skull to D1 vertebra with both sagittal and coronal reconstructions for precise assessment.[7] Magnetic resonance imaging (MRI) is the most sensitive diagnostic tool to evaluate soft tissues such as disc herniation, ligament injury, and associated spinal cord injury.[7] MRI is mandatory for patients undergoing open surgical reduction and fixation.[8] The rationale of treatment is to maintain the functional and anatomical integrity of the spinal column.[9] The dislocated facets are reduced to decompress the neural elements and restore stability. Closed or open techniques can achieve the reduction of facet dislocation. Contraindications to closed reduction include injury to craniovertebral ligaments, disc prolapse, or evidence of retropulsed bony fragments that can compress the cord during the reduction process. Open surgical reduction and fixation are indicated in failed closed reduction cases and those contraindicated for closed reduction. The options for surgical approach for unilateral or bilateral facet dislocations include a stand-alone anterior approach/posterior approach or a combined anterior and posterior approach (circumferential), which can be staged or in a single setting depending on the clinical status of the patient.[9] The optimal management of these injuries remains controversial (no level 1 evidence) in terms of type of reduction, its timing, type of surgical approach, and method of fixation. FEASIBILITY OF STAND-ALONE ANTERIOR REDUCTION AND FIXATION OF SUBAXIAL CERVICAL SPINE IN FACETAL DISLOCATIONS Posterior reduction and fixation have been advocated for managing facetal dislocations. This approach, however, has many disadvantages, such as the risk of neurologic deterioration in the presence of traumatic disc prolapse and postoperative axial neck pain. Hence, a stand-alone anterior reduction and fixation are advocated by many spine surgeons as it has various advantages such as less soft-tissue injury, lower infection rates, and reduced risks of secondary spinal cord injury. There is a 25%–40% reduction in failure rate in case of resistant and delayed bilateral facet dislocations.[10] The accepted treatment for such injuries is a combined anterior and posterior cervical (circumferential) approach. However, this approach is both time-consuming and needs shifting the patient from prone to supine position (sometimes requiring 540° mobilization). Hence, many schools thought of a stand-alone anterior intraoperative reduction and alignment of the spinal column in facetal dislocations. Unilateral dislocation differs from bilateral dislocation in that, bilateral facet dislocation involves disco ligamentous injuries along with posterior annulus tear causing traumatic disc herniation. There is good evidence in literature to support a stand-alone anterior approach for unilateral facetal subluxation. However, there is concern over the stability of the anterior-alone approach in bilateral dislocation due to marked posterior tension band injury. Systematic reviews show that the anterior-alone approach is also efficacious in bilateral dislocation without extensive facet fractures.[10] Anterior cervical discectomy and reduction of dislocation followed by interbody grafting and fusion help to restore near-physiological lordosis and aids in stabilizing the motion segment. Stand-alone anterior approach is advantageous in that it also prevents further iatrogenic injury to the posterior disco ligamentous complex in comparison to the posterior approach. There are many anterior open surgical techniques to reduce and fix facetal dislocations. However, none of the procedures are standardized. We have, therefore, developed a stand-alone anterior reduction and fixation technique for stabilizing subaxial cervical spine in flexion-distraction-rotation injuries. In this editorial, I would like to demonstrate and highlight a novel cost-effective “Anterior Flexion Distraction” technique using Casper pin distractors for reducing facetal dislocation of the subaxial cervical spine. This technique obviates the need for skeletal traction or posterior cervical spine exposure. DEMONSTRATION OF TECHNIQUE Representative case A 39-year-old female presented with severe neck pain following traumatic C5-C6 subluxation after a road traffic accident. On examination, she had a left upper limb weakness with evidence of compressive cervical myelopathy. The X-ray of the cervical spine showed C5-C6 subluxation [Figure 1]. A cervical spine CT confirmed the same with bilateral locked facets [Figure 2]. MRI revealed cord contusion extending from level C4 to C6 [Figure 3].Figure 1: X-ray showing C5 C6 subluxation with bilateral locked facetsFigure 2: Computed tomography cervical spine showing subluxation of C5 over C6 with bilateral locked facetsFigure 3: Magnetic resonance imaging showing spinal cord contusion extending from level C4-C6PROCEDURE OF REDUCTION Positioning and anesthesia Supine position with fiberoptic intubation under general anesthesia with neurophysiological monitoring (Motor-Evoked Potentials) is essential to minimize the risk of neurologic injury. Distraction pins were inserted into the concerned vertebral body at a divergent angle of 10–20 degrees. Bringing the pins into a parallel orientation followed by controlled distraction results in disengagement of the facet by creating a focal kyphosis. The rostral level is then translated dorsally with the application of moderate pressure to restore alignment [Figure 4].Figure 4: Placing distraction pins at a 10°–20° angle with respect to each other in the sagittal plane permits the creation of a kyphosis to disengage the facets. Dorsal force application to the rostral vertebra assists in reduction of the dislocationPlacing the pins at a 15° angle with respect to each other in a coronal plane allows the reduction of a rotational deformity when distraction is applied. In the case of a unilateral dislocation, the distraction pins should be applied with a divergent angle in the coronal plane to allow the rotational deformity to be reduced after distraction [Figure 5].Figure 5: Placing the pins at a 15° angle with respect to each other in coronal plane allows reduction of a rotational deformity when distraction is appliedDifficulties to be anticipated The dislocation may sometimes be challenging to reduce. Therefore, be prepared to perform a posterior procedure if necessary. If there is a sagittal plane deformity (kyphosis) at the injured level, the caudal portion of the rostral body may be resected with a high-speed drill to allow access to the disk space [Figure 6].Figure 6: The caudal portion of the rostral body may be resected with a high-speed drill to allow access to the disk spacePostoperatively, the neck pain reduced, and weakness improved to grade 4+. CT scan and X-ray showed a good reduction [Figure 7]. The patient was discharged from the hospital on the 3rd day with a cervical collar.Figure 7: (a) X-ray showing good reduction and fixation. (b) Postoperative computed tomography scanAdvantages of the procedure Intraoperative blood loss was minimal, and we reduced operating time and avoided a 540-degree surgical approach. Thus, the stand-alone anterior approach avoided the need for a staged procedure. I strongly feel that “Anterior Flexion Distraction” technique is a cost-effective technique as it preserves the posterior tension band and reduces the risk of secondary spinal cord injury following intraoperative mobilization of patient with minimal cost of implants preserving the PLC. Limitations This technique needs further randomized controlled trials for level 1 evidence. Further research and biomechanical feasibility using anatomical ex vivo and in vivo constructs must be done to validate further the appropriateness and safety of the Anterior Flexion Distraction Technique for reducing traumatic subaxial facet dislocations. Declaration of patient consent 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. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

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