The classification and surgical management for axis fracture complicated with adjacent segment instability

English Keywords:Axis Fractures  Adjacent section instability  Classification  Operative methods

English Abstract:

  【Ａbstract】 Objectives: To provide the classification of axis fracture complicated with adjacent segment instability and investigate its significance to surgical management. Methods: 47 patients(31 males and 16 females) with axis fractures from August 2003 to June 2011 with a mean age of 32 years(range, 19 to 59) were treated surgically and analyzed retrospectively. The Frankel scale was used to assesse neurofunction as following: 1 grade A, 2 grade B, 3 grade C and 5 grade D before surgery. The classification was determined according to the fracture type and stability of adjacent segment. Type A(21 cases): axis fracture with C1/2 instability; Type B(17 cases): axis fracture with C2/3 instability; Type C(9 cases): axis fracture with both C1/2 and C2/3 instability. Operations were performed as following: Type A, posterior atlantoaxial fixation plus anterior screw fixation for odontoid fracture; Type B, anterior discectomy, fusion, and cervical plate fixation; Type C, posterior C1-C3 fixation or occipitocervical fusion when C1-C2 fusion was unavailable. JOA score was applied to evaluate the therapeutic effect. The fracture healing, bone graft fusion and stability were observed on X-ray or CT scan. Results: All patients underwent surgery safely without spinal cord injury, cerebrospinal fluid leakage and vertebral artery injury. The average follow-up was 15 months(9-48 months). There was significant difference(P＜0.05) in JOA score between pre-operation(10.60±3.29) and post-operation(13.83±3.93), and the rate of improvement was 72.3%-90.8%, with the excellent to good rate of 98%. 1-2 degree improvement of neurofunction was achieved in all except 1 Frankel B. After operation, all patients were immobilized in a hard collar for 3 months. Fusion was achieved in 39 cases from 3 to 6 months(mean 4.5 months). X-ray verified no malposition of the screws. No instrument failure was noted during follow-up. Conclusions: Axis fracture complicated with adjacent segment instability should be treated individually based on fracture type and adjacent segment instability, and the classification can be used to guide the surgical management.