ABSTRACT
BACKGROUND:Previous clinical fol ow-up study showed that disc degeneration of adjacent segment after anterior cervical discectomy and fusion was faster than that of artificial cervical disc replacement. Compared with the anterior cervical discectomy and fusion, artificial cervical disc replacement can maintain a good range of motion of replacement segment. Further investigation should be taken to compare the difference between stress and fusion after replacement. OBJECTIVE:To compare the adjacent level discs loads between artificial cervical disc replacement and anterior cervical discectomy and fusion. METHODS:A healthy 30-year-old male volunteer was scanned with CT at the artificial cervical intervertebral disc and anterior cervical plate. Three-dimensional images were reconstructed with Mimics 10.01 and Geomagic Studio.v11 software. Above three-dimensional data were input into the Abaqus6.9 finite element analysis software for meshing, assignment, and stress analysis. Finite element method was used to simulate the stress changes of the adjacent segments after artificial cervical disc replacement and anterior cervical discectomy and fusion. RESULTS AND CONCLUSION:(1) Under the same preload, during anteflexion, posterior extension, and lateroflexion, the disc stress at adjacent segment was significantly larger after anterior cervical discectomy and fusion than normal disc. Compared with normal persons, no significant difference was detected in stress of adjacent segment at anteflexion, posterior extension, and lateroflexion after artificial cervical disc replacement. (2) Compared with artificial cervical disc replacement group, the stress of adjacent segment increased 10.3%-51.6%in the anterior cervical discectomy and fusion group. (3) Finite element analysis showed that the stress was larger in the anterior cervical discectomy and fusion group than in the artificial cervical disc replacement group. With prolonged fol ow-up, compared with the conventional anterior decompression and fusion, artificial cervical disc replacement can better play its protective effect on the adjacent intervertebral disc.
ABSTRACT
[Objective]To evaluate the surgical results of posterior hemivertebra resection in the treatment of congenital kyphoscoliosis caused by hemivertebra.[Method]From May 2000 to November 2005,14 cases with hemivertebra treated with one stage posterior hemivertebra resection were reviewed,which included males and females.All the cases underwent one stage posterior hemivertebra resection,fusion and correction with instrumentation.The mean age at time of surgery was 7.4 years old.Location of the hemivertebra included 7 cases at thoracic spine and 7 cases at lumbar spine.[Result]The mean operation time was 4.7 hours,the mean blood loss and blood transfusion during operation was 500 ml and 560 ml respectively.The fusion level was 2 to 8 segments,average 3.5 segments.Scoliosis was corrected from 46.2? to 17.3?with a correction rate of 62.6%.Kyphosis was corrected from 48.3? to 16.2? with a correction rate of 68.7%.At the final follow-up,the coronal Cobb's angle was 21.7? with a 4.4? loss of correction;the sagittal Cobb's angle was 18.7 with a 2.50 loss.Peri-operative complication included two of implant malposion,delayed wound healing.No reoperation due to the progressive deformititie was need.[Conclusion]One stage posterior hemivertebra resection has a good capability of correcting congenital kyphoscoliosis caused by a singe hemivertebra.It can save operation time and is less invasive compared to combined approach,and is indicated to thoracic and lumbar hemi-vertebra with fewer complications.