[Treatment of odontoid fracture combined with lower cervical spinal cord injuries without fracture or dislocation]

To discuss the clinical characteristics, mechanism, and treatment of odontoid fracture combined with lower cervical spinal cord injuries without fracture or dislocation.

According to the inclusion and exclusion criteria, 7 male patients aged 37-71 years (mean, 51.4 years), suffered from odontoid fractures combined with lower cervical spinal cord injuries without fracture or dislocation were analyzed retrospectively between June 2007 and October 2015. The trauma causes were traffic accidents in 2 cases, fall in 2 cases, and hit injury in 3 cases. The time from injury to admission was 2 hours to 3 days with an average of 9 hours. According to Anderson-Grauer classification of odontoid fracture, 1 case of type IIA, 3 cases of type IIB, 2 cases of type IIC, and 1 case of shallow type III were found. The cervical spinal cord injuries affected segments included C _{4, 5} in 1 case, C _4-6 in 2 cases, and C _5-7 in 4 cases. All the cervical spine had different degenerative changes: 2 of mild, 3 of moderate, and 2 of severe. The lower cervical spinal cord injury was assessed by Sub-axial Injury Classification (SLIC) with scoring of 4-6 (mean, 5.1). The visual analogue scale (VAS) score was used to evaluate the occipital neck pain with scoring of 7.8±1.0; the neurological function was assessed by American Spinal Injury Association (ASIA) as grade B in 1 case, grade C in 4 cases, and grade D in 2 cases; and Japanese Orthopedic Association score (JOA) was 9.2±3.9. For the odontoid fractures, 4 cases were fixed with anterior screw while the others were fixed with posterior atlantoaxial fixation and fusion. For the lower cervical spine, 4 cases were carried out with anterior cervical corpectomy and titanium fusion while the others with anterior cervical disecotomy and Cage fusion.

The operation time was 178-252 minutes (mean, 210.2 minutes); the intraoperative blood loss was 60-140 mL (mean, 96.5 mL) and with no blood transfusion. All incisions healed primarily. All the patients were followed up 12-66 months (mean, 18 months). There was no direct surgical related complications during operation, and all bone grafting got a fusion at 6-9 months (mean, 7.7 months) after operation. There was no inter-fixation failure or loosening. At last follow-up, the VAS score declined to 1.7±0.7 and JOA score improved to 15.1±1.7, showing significant differences when compared with preoperative ones ( t=18.064, P=0.000; t=-7.066, P=0.000). The neurological function of ASIA grade were also improved to grade D in 5 cases and grade E in 2 cases, showing significant difference ( Z=-2.530, P=0.011).

Complex forces and degeneration of lower cervical spine were main reasons of odontoid fracture combined with lower cervical spinal cord injuries without fracture or dislocation. The type of odontoid fracture and neurological deficit status of lower cervical spinal cord were important to guide making strategy of one-stage operation with a satisfactory clinic outcome.