[Relationship between the prediction of the opening angle and the increased value of cross-sectional area in single open-door laminoplasty].

OBJECTIVE: To evolve the formula of relationship between opening angle of laminoplasty and the increased value of cross-sectional area, and to predict the opening angle according to the opening size of lanminoplasty. METHODS: From January 2013 to December 2015, 26 patients underwent single open-door laminoplasty in C3-C7. Among them, 10 patients with ossification of posterior longitudinal ligament, there were 6 males and 4 females, aged from 39 to 58 years old with an average of 49.2 years; and 16 patients with cervical spondylotic myelopathy, there were 10 males and 6 females, aged from 40 to 58 years old with an average of 50.2 years. Through the changes of spinal canal shape between preoperation and postoperation to set up the regular geometric model, and to deduce the formula of the relationship between the opening angle of laminoplasty and the increased value of cross-sectional area, and predict the formula of opening angle. According to the preoperative and postoperative CT scan, the needed parameters were measured, and were substituted in the above formula to get the change of cross-sectional area before and after operation, predicting the opening angle of laminoplasty. The differences between the change of cross-sectional area before and after operation, predictive the opening angle of laminoplasty and practical measured data were analyzed by statistical methods, thus to verify the feasibility of formula in practical application. RESULTS: All imaging data of 26 patients were obtained. There were significant differences in changes of cross-sectional areas in every patients (laminoplasty in C3 to C7) before and after operation in the same segment(P<0.01). The increasing extent in cross-sectional areas was gradually diminished following the opening angle increasing. There was no significant difference between the opening angle attained by formula and the data measured by software in the same segment(P>0.05). CONCLUSIONS: Increment of cross-sectional areas following C3-C7 laminoplasty can be accurately attained and the opening angle can also be predicted by a certain formula, which can help surgeons to attain the accurate opening angle and reduce the postoperative complications.

[Clinical application of dynamic neutralization system (K-Rod) in treating multisegmental lumbar degenerative disease].

OBJECTIVE: To evaluate the clinical effects of dynamic neutralization system (K-Rod) in treating multisegmental lumbar degenerative disease. METHODS: From October 2011 to October 2013, 20 patients with multisegmental lumbar degenerative disease were treated with dynamic neutralization system (K-Rod). There were 8 males and 12 females with an average age of 45.4 years old (ranged from 31 to 65) and an average course of 3.8 years (ranged from 9 months to 6.25 years). All patients had the history of low back and legs pain. Among them, 10 cases were far lateral lumbar disc herniation, 7 cases were lumbar spinal stenosis, 3 cases were lumbar spondylolisthesis (degree I in 2 cases and degree II in 1 case). Every patient had only one responsible segment which causing the symptom would have to be rigidly fixed during operations, and the adjacent intervertebral disc of the responsible segments at least 1 segment has already obvious degenerated. All patients underwent the operation to relieve compressed nerves and reconstruct spinal stability with K-Rod system (the responsible segments were fixed with interbody fusion, and the adjacent segments were fixed with dynamic stabilization). Visual analogue scale (VAS), Japanese Orthopaedic Association Scores (JOA) and Oswestry Disability Index (ODI) were used to evaluate the clinical effects. Imaging data were used to analyze the range of motion (ROM), intervertebral disc height and intervertebral disc signal (according to modified Pfirrmann grading system) in degenerative adjacent segment. RESULTS: All patients were followed up for more than 1 year, and preoperative symptoms obviously relieved. There were significant differences in VAS, JOA, ODI between preoperative and postoperative (postoperative at 1 week and 1 year) (P<0.05). Radiological examination showed that all responsible segments had already fused, and no looseness, displacement and breakage of internal fixations were found. Postoperative at 1 year, the ROM of adjacent segments were decreased (P<0.05). There was no significant difference in intervertebral disc height between preoperative and postoperative at 1 year (P>0.05). According to modified Pfirrmann grading system to classification for the 25 disks of adjacent segment, 8 disks (32%) got improvement, 15 disks (60%) got no change and 2 disks (8%) got aggravation at 1 year after operation. CONCLUSION: Dynamic neutralization system (K-Rod) combined with interbody fusion could obtain short-term clinical effects in the treatment of multisegmental lumbar degenerative disease.