Classification of unilateral cervical locked facet with or without lateral mass-facet fractures and a retrospective observational study of 55 cases

Abstract

This study describes a morphology-based unilateral cervical facet interlocking classification in an attempt to clarify the injury mechanism, instability, neurological deficits, radiological features, and determine optimum management strategies for these injuries. A total of 55 patients with unilateral cervical locked facet (UCLF) involving C3 to C7 were identified between January 1, 2012 and December 1, 2019. The injuries were classified into three types, and they were further divided into six subtypes using three-dimensional computed tomography. The injury mechanism, clinical features, neurological deficits, and imaging characteristics were analyzed, and the appropriate treatment strategies for UCLF were discussed. UCLFs were divided into the following six subtypes: UCLF without lateral mass-facet fracture (type I) in nine cases, with superior articular process fracture (type II A) in 22, with inferior articular process fracture (type II B) in seven, both superior and inferior articular process fractures (type II C) in four, with lateral mass splitting fracture (type III A) in three, and with lateral mass comminution fractures (type III B) in ten. A total of 22 (40.0%) of the 55 patients presented with radiculopathy, and 23 patients (41.8%) had spinal cord injuries. The subtype analyses showed high rates of radiculopathy in types II A (68.2%) and II C (75.0%), as well as significant spinal cord injury in types I (77.8%) and III (61.5%). Destruction of the facet capsule was observed in all patients, but the injury of disc, ligamentous complex, and vertebra had a significant difference among the types or subtypes. The instability parameters of the axial rotation angle, segmental kyphosis, and sagittal displacement showed significant differences in various types of UCLF. Closed reduction by preoperative and intraoperative general anesthesia traction was achieved in 27 patients (49.1%), and successful rate of closed reduction in type I (22.2%) was significantly lower than that in type II (51.5%) and type III (61.5%). A total of 35 of 55 patients underwent a single anterior fixation and fusion, 10 patients were treated with posterior pedicle and (or) lateral mass fixation, and combined surgery was performed in ten patients. Ten patients (18.2%) with a poor outcome were observed after first surgery. Among them, 3 patients treated with a single anterior surgery had persistent or aggravated radiculopathy and posterior approach surgery with ipsilateral facet resection, foramen enlargement, and pedicle and (or) lateral mass screw fixation was performed immediately, 5 patients treated with a short-segment posterior surgery showed mild late kyphosis deformity, and 2 patients with vertebral malalignment were encountered after anterior single-level fusion during the follow-up. This retrospective study indicated that UCLF is a rotationally unstable cervical spine injury. The classification proposed in this study will contribute to understanding the injury mechanism, radiological characteristics, and neurological deficits in various types of UCLF, which will help the surgeons to evaluate the preoperative closed reduction and guide the selection of surgical approach and fusion segment.

Verletzungen der subaxialen Halswirbelsäule

“…Verletzungen der Typen B1-3, C und F3/F4 haben eine hohe Wahrscheinlichkeit einer Läsion der A. vertebralis [21,22,23,24,25]. Auch bei neurologisch asymptomatischen Patienten sollte in diesen Fällen daher eine Gefäßdarstellung der A. vertebralis erfolgen (CT-Angiografie oder MR-Angiografie).…”

Traumatic Cervical Facet Fractures and Dislocations

“…Unilateral facet dislocations cause subtle disruption of normal spinal alignment and may be missed on radiographs. Soft-tissue injuries frequently accompany unilateral dislocation, including injuries to the PLC and intervertebral disc herniations (56% of cases) 12,13 .…”

Surgical outcome of locked facet in distractive flexion injury of the subaxial cervical spine: Single institution retrospective study

“…Although facet subluxation/dislocation is usually reducible preoperatively by traction maneuvers, subaxial cervical spine facet joint dislocations are difficult to reduce when complicated by posterior facet fractures or ligamentous injury. [3,4] In particular, surgical treatments are required for cases with a locked facet (LF), which is defined as a subluxation/dislocation that is irreducible preoperatively, even at a maximum load of skeletal traction, or for which further traction is impossible because of worsening neurologic symptoms. [5] Although the DFI treatment has been previously introduced, [6,7] the treatment option for such locked facet distractive flexion injury (LF-DFI) remains controversial, and the optimal strategies and approaches to reduce the LF have not been fully evaluated.…”