Surgical Management Of The Fractures Of Axis Body

Backgroud: Axis fractures represent more than 20% of cervical spine fractures, of which most are odontoid fractures or Hangman’s fractures, small part are axis body fractures. Due to the complex injury mechanisms, the fractures of the axis body have a variety of presentations, and there is still much controversy on their definition, classification and clinical management. Nonoperative treatment was suggested as primary therapy for the fractures of the axis body previously with satisfactory clinical results for most patients. However, some axis body fractures are intrinsically unstable due to serious displacement or associated dislocation/subluxation of adjacent joints. And the superior articular facets of the axis are often involved in many fractures, C2 malunion and the atlanto-axial degeneration and osteoarthritis results in chronic neck pain and reduce rotation of the C1-C2 inevitably. Surgical management for fractures of the axis body has previously only been reported infrequently as case reports or included as a minor part of clinical management at home and abroad, and the surgical indications and strategy are still not very clear. However, with the advancement of imaging technique, especially the application of three-dimensional multi- slice spiral CT, many complex or rare axis body fractures have been able to be depicted and identified accurately. Moreover, the C1 pedical screws, when combined with the C2 pedical screws have shown obvious superiority in reduction. Many cases of axis body fractures, which previously could only be treated with nonoperative management or with surgical management via combined anterior and posterior approaches, are now able to obtain better clinical results through operative management with a simple posterior approach.Objective: This study is to summarize the indications for surgery of the axis body fractures and the surgical strategy based on different fracture patterns.Methods: Of the 36 consecutive patients presenting with the axis body fractures, 17 treated operatively were analyzed retrospectively. Patients who were diagnosed as fractures of the axis body with careful physical and imaging examination were included in this study. Patients were not included if they were complicated with old fractures/dislocation, rheumatoid arthritis, infections, tumor, or deformities of the upper cervical spine, or were younger than 18-year old, or if the medical records were not complete. The axis body fractures were categorized into five subtypes: sagittal, coronal, transverse, tear-drop and unilateral lateral mass fracture. The 17 patients were treated with skull traction for 1–2 weeks for reduction firstly after admission. One of the following surgical procedures was applied according to the fracture pattern: posterior C1–C2 pedicle screws fixation and fusion(I); posterior C1–C2 pedicle screws and C3 lateral mass screws fixation and fusion(II); posterior osteosynthesis with C2 transpedicular half-thread lag screws with/without laminar screws(III); anterior fracture reduction and C2-3 discectomy and fusion( supplemented with posterior C2-3 fusion when the bone fragment was very big)( IV). The fracture healing was confirmed when the fracture line was indistinct on the X-Ray radiograph or CT of the cervical spine. The bony union of the fixed segments was considered to be present when a bone bridge was seen on the CT scans,or there was no implant failure or evidence of instability on follow-up image views. The neurological function was assessed with modified Frankel index. A standard Visual Analogue Scale( VAS) of 10 points was used to assess neck pain, and the primary clinical outcome was valuated accroding to Odom criteria at the final follow-up.Results: 17 patients were successfully managed operatively. Surgical indications could be summarized as :(1) fractures associated with instability of the adjacent joints, such as atlanto-axial facet joint dislocation/subluxation, C2/3 dislocation/subluxation and damage of C2/3 disc or the integrity of the C1–C2 and C2–C3 interspinal ligamentous system;(2) irreducible displaced lateral mass fractures impacting the superior articular facets of the axis;(3) fractures resulting in spinal cord compression. Two transverse and three unilateral lateral mass fractures were treated with surgical procedure I, five sagittal fractures with II, four coronal fractures with III, three tear-drop fractures with IV. All cases obtained satisfactory reduction of fractures and dislocation/subluxation without complications of malposition of screws and neurologic deficit did not occur during operation. All patients were followed up for a mean duration of 18.1 months( ranging from 6 to 45 months). The fracture healing and the bony union of the fixed segments were revealed in all cases on radiograph or CT of the cervical spine at the 6th month follow-up. Four patients presenting with neurological deficits gained various degrees( 1-2 Frankel grades) of improvement of neurological function postoperatively. All patients with atlanto-axial fusion had restrictions of cervical rotation of different degrees at the final follow-up. Four patients with coronal fractures who were treated with only posterior axis transpedicular half-thread lag screws showed nearly normal range of cervical motion at the 6th month follow-up. Implant displacement and break were not seen on the lateral flexion/extension radiographs of the cervical spine, the average VAS scores were 0.8( ranging from 0 to 2), and 6 were excellent, 10 were good, 1 was fair accroding to Odom criteria at the last follow-up.Conclusions: Conservative remedies with external immobilization is still advocated as primary management for most axis body fractures due to their small displacement and stability. But for cases with adjacent joints instability, irreducible displaced superior articular facet fractures, or spinal cord compression, surgical intervention is still necessary. With the advancement of diagnosis and surgical technique of the upper cervical spine and the improvement of safety of surgery, more and more axis body fractures could be treated surgically for better clinical results avoiding complications of long term bed rest and external immobilization. In order to preserve the normal motion segments as far as possible on the base of fracture reduction and stability reconstruction of the upper cervical spine, the optimal surgical choice should be based on the type of fracture pattern. The fractures of axis body are rare and often present variablely, and this study is based on the experience of a single medical institution, the results need to be proved with prospective multicentre studies with long term follow-up.