We designed this study to evaluate the incidence of spinal cord injury and the results of surgical treatment of lower cervical spine injury, and to suggest a rational treatment guideline according to the stages of Allen's mechanistic classification of the lower cervical spine injury.

We reviewed the medical records and roentgenograms of 66 patients (49 men and 17 women), who were treated surgically for acute fracture and dislocation of the lower cervical spine since March. 1991 to March. 1996. These patients ranged in age from 17 to 68 years (average age- 38 years). We used Allen's mechanistic classification to analyze fractures in the lower cervical spine injury. We divided neurologic status by complete, incomplete, root injury and no neurologic deficit group, Surgical treatment was performed for those with unstable fracture/dislocation, progressive neurologic deficit with conservative care, neurologic deficit with spinal cord compression by fracture fragment or extruded disc material. Surgical approach was determined according to the site of lesion. We analyzed the surgical treatment results according to neurologic recovery, radiologic bone union and complications, We used chisquare test for statistical analysis of neurologic improvement between the different surgical treatments.

Twenty-nine cases were distractive-flexion (DF) phylogeny, 19 cases were compressive-flexion (CF), 2 cases were vertical-compression (VC), 8 cases were compressive-extension (CE), and 8 cases were distractive-extension (DE) phylogeny. For definitive surgical treatments we performed anterior cervical discectomy and fusion (ACDF) in 25, ACDF with anterior stabilizaiton in 30, posterior fusion in 5, and circumferential fusion in 6. There was no neurologic recovery in complete cord injury. There were 32 cases of incomplete cord injury all 8 anterior cord syndromes had no neurologic recovery, among 22 patients with central cord syndrome 18 had neurolgic recovery in various degrees and 2 with Brown-Seguard syndrome showed significant neurologic recovery. In nerve root injury, all patients had complete neurologic recovery. There was no radiologic nonunion at all and it took 10.3 weeks in average for radiologic bone union. There were neurogenic bladder, bed sore, local kyphosis, duodenal ulcer, respiratory infection, persistent neck pain and superficial wound infection in complications.

In extension (CE, DE) injuries with neurologic deficit, anterior approach should be recommended because the major pathology is located in the anterior structure of the cervical spine. In flexion (DF and CF) injuries with major posterior osteoligamentous disruption, posterior approach could fix the posterior structures. Anterior decompression and fusion should be followed whenever anterior pathology is compressing the spinal cord or nerve root. Posterior open reduction and fusion is necessary whenever there is unreduced facet joint dislocation with or with out neurologic deficit. To prevent the late local kyphosis and persistent neurologic deficit with neck pain after prolonged external immobilization with ACDF, anterior stabilization with a plate and screw system is necessary to augment the surgical treatment of the unstable lower cervical spine injury which necessitates anterior decompression.