Surgical management for old dislocation of the subaxial spine

English Keywords:Low cervical spine  Old dislocation  Operation

English Abstract:

  【Abstract】 Objective：To investigate surgical strategy and short-term clinical outcome for old dislocation of the subaxial spine.Method：Twenty-three patients with old dislocation of subaxial spine were treated surgically from June 2004 to February 2008.Dislocation vertebrae were C4 in 4 patients，C5 in 5，C6 in 10 and C7 in 4.According to ASIA criterion，neurological status was grade A in 2 patients，grade B in 1，grade C in 5，grade D in 8 and grade E in 7.All 23 patients were performed skull traction prior to surgery.The canal-vertebrae（C/V） ratio at narrowest site of involved segment was measured from CT scan images of sagittal reconstruction.The surgical procedure was determined based on the ratio and the status of facets interlocking.Of 15 patients with C/V ratio over 0.5，6 with no facets interlocking underwent anterior reduction and fusion，9 with facet interlocking were managed as follows：3 cases with bilateral facets interlocking experienced closed reduction by skull traction under general anesthesia followed by anterior fusion，and the other 6 patients irresponsible to skull traction experienced posterioer realignment and fusion followed by anterior fusion and instrumentation.Five cases with C/V ratio less than 0.5 were managed with anterior release and decompression，then posterior reduction and fixation，after that anterior fusion was performed afterwise.Three cases with C/V ratio less than 0.3 underwent anterior release，followed by posterior laminectomy and reduction，finally anterior decompression and fusion was performed.Neck disability index（NDI） and visual analog scale（VAS） was used to evaluate neck function and pain.Additionally ASIA criterion was used for neurological assessment.Result：The average surgical time was 105min，no intra-operative complications were noted.The average blood loss was 280ml，and the average hospital stay was 15.7 days.Post-operative complications were seen in 2 cases，one developed fat liquefaction at skin incision which was cured by changing dressing，the other had one screw loosing which was resolved by removal of anterior implant.20 patients were followed up for an average of 28 months（range，15-48 months）.The C/V ratio improved significantly from preoperative 0.56±0.27 to postoperative 0.86±0.07（P<0.05） and 0.88±0.06 at 6 months follow-up.NDI and VAS score at 3，6，12 months after operation decreased 24% for 2.4，26% for 2.8 and 35% for 3.3 respectively.Successful interbody fusion occurred in all 20 patients at 6 months.10 patients had neurologic function improved，however 3 cases remained unchanged（1 grade A，1 grade B and 1 grade D） at 12 months.Conclusion：The surgical strategy for old subaxial dislocation should be referred to the canal-vertebrae（C/V） ratio and status of facets interlocking at narrowest site of involved segment from CT scan images of sagittal reconstruction，which can reconstruct subaxial spine stability and ensure a good early outcome.