Biomechanical study on effect of upper cervical spine structural injury on stability of C1-C2 and C2-C3 segments / 中华创伤杂志

ABSTRACT

Objective To evaluate the effect of type Ⅱ odontoid fracture,type Ⅰ Hangman fracture,C2-C3 disc injury on stability of C1-C2 and C2-C3 segments and investigate the clinical significance.Methods Ten fresh-frozen cadaveric cervical specimens (5 men and 5 women; 25-45 years of age,mean 35.7 years) were selected to test the stability of C1-C2 and C2-C3 segments in the settings of intact condition (control group),type Ⅰ Hangman fracture,type Ⅱ odontoid fracture,type Ⅰ Hangman fracture + type Ⅱ odontoid fracture,type Ⅰ Hangman fracture + type Ⅱ odontoid fracture + C2-C3 disc injury.Range of motion (ROM) and neutral zone (NZ) of those segments were measured.Results Compared with the intact condition,type Ⅰ Hangman fracture produced no significant variations in C1-C2 ROM in all loading modes and C2-C3 ROM during left and right lateral bending; type Ⅱ odontoid fracture produced no significant variations in C2-C3 ROM in all loading modes and C1-C2 ROM during left and right rotation; type Ⅰ Hangman fracture + type Ⅱ odontoid fracture revealed no significant variations in C1-C2 ROM during left and right rotation and C2-C3 ROM during extention; type Ⅰ Hangman fracture + type Ⅱ odontoid fracture + C2-C3 disc injury produced no significant variations in C1-C2 ROM during left and right lateral bending and extension-flextion and C2-C3 ROM in all loading modes (P ＜ 0.05).Conclusions Type Ⅰ Hangman fracture can reserve C1-C2 segmental left and right rotation and extension-flextion; type Ⅱ odontoid fracture can reserve C1-C2 segmental left and right lateral bending and extension-flextion; type Ⅰ Hangman fracture + type Ⅱ odontoid fracture + C2-C3 disc injury can reverse atlantoaxial rotationary stability and C1-C3 segmental stability in all directions.This study provides the biomechanical basis for clinical treatments and the related researches of internal fixation.