Abstract:

BACKGROUND: Up to now, it is scarcely reported that the biomechanical stability of the thoracolumbar posterior longitudinal ligament (PLL) in anterior decompression.
OBJECTIVE: This biomechanical study was undertaken to determine the role of thoracolumbar PLL following anterior decompression and interbody iliac bone graft fixed with Kaneda instrumentation.
METHODS: A total of seven fresh calf thoracolumbar spines (T₁₁-L₃) following the trial procedure were noted as normal group (the PLL was intact without decompression and internal fixation), intact PLL group (the PLL was intact with decompression, bone graft and internal fixation), resected PLL group (the PLL was cut with decompression, bone graft and internal fixation). The biomechanical property was determined with experimental stress methods. L₁ vertebra excision, anterior decompression and interbody iliac bone graft + Kaneda internal fixation were performed. Nondestructive biomechanical tests were performed with WE-10A testing machines. The data of strain, stress, axis compression stiffness, rotational rigidity were recorded and calculated, then analyzed by F test.
RESULTS AND CONCLUSION: Following thoracolumbar anterior decompression and bone graft + Kaneda internal fixation, when the PLL was cut, the stability of the specimen tended to decrease at rotation, axial compression, flexion, extension and lateral bending. The decrease at flexion was the most remarkable with significant differences (P < 0.05). During the thoracolumbar anterior decompression and internal fixation, the resection of the PLL may lead to the instability of spine cord at flexion, which is bad for bone graft fusion. So the normal PLL should be protected.