Background Coflex, a type of interspinous process implant, can provide intervertebral dynamic stability for surgical segments and effectively relieve lumbocrural pain. However, few studies have described therapeutic s...Background Coflex, a type of interspinous process implant, can provide intervertebral dynamic stability for surgical segments and effectively relieve lumbocrural pain. However, few studies have described therapeutic strategies and the avoidance of Coflex implant complications. Methods Coflex implant complications in this study included intraoperative or postoperative spinous process fracture, aggravated postoperative lumbocrural pain, dislodgment and malposition. The complications were analyzed, and therapeutic strategies were applied according to the specific complication. The Visual Analogue Scale and Oswestry Disability Index scores were evaluated by using the paired-samples test from SPSS 12.0. Results Conservative treatment was provided to seven patients who experienced aggravated lumbocrural pain even though their devices remained in the correct position, and pedicle screw treatment was used as an alternative in four cases. The Visual Analogue Scale and Oswestry Disability Index scores showed evident improvement in these patients. The Visual Analogue Scale and Oswestry Disability Index scores of two patients who underwent revision were also improved. Conclusions Coflex implants should be avoided in patients with osteoporosis, a narrow interspinous space and intervertebral coronal spondylolysis, or sagittal instability. Furthermore the device choice, depth of implantation, and clamping intensity should be appropriate. Conservative treatment can be provided to patients with symptoms if the device remains in the correct position; however, revisions and salvages should be undertaken with internal fixation of pedicle screws for patients with device malposition, intraoperative implantation failure, or device intolerance.展开更多
Dynesys,a pedicle-based dynamic stabilization system,was introduced to overcome some undesirable complications of fusion procedures.Nevertheless,the theoretical advantages of Dynesys over fusion have not been clearly ...Dynesys,a pedicle-based dynamic stabilization system,was introduced to overcome some undesirable complications of fusion procedures.Nevertheless,the theoretical advantages of Dynesys over fusion have not been clearly confirmed.The purpose of this editorial was to compare clinical and radiological outcomes of patients who underwent Dynesys system with those who underwent posterior lumbar fusion according to the existing literature and to see if the application of the Dynesys system is superior to the traditional lumbar fusion surgery.According to published clinical reports,the short-term effects of the Dynesys dynamic stabilization system are similar to that of traditional lumbar fusion surgery.Three comparative studies of Dynesys dynamic stabilization and fusion surgery with medium-term follow-up are encouraging.However,the results from four single-treatment-arm and small-sample studies of case series with long-term follow-up were not encouraging.In the present circumstances,it is not possible to conclude that the Dynesys dynamic stabilization system is superior to fusion surgery for lumbar degenerative diseases.展开更多
This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two...This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two dynamic parameters.Specifically,a set of auxiliary variables is first introduced through state transformation.These variables combine the original system states and the two introduced dynamic parameters,facilitating the closed-loop system stability analyses.Then,the two dynamic parameters are delicately designed by utilizing the Lyapunov method,ensuring that all the closed-loop system states are globally fixed-time stable.Compared with existing results,the“explosion of complexity”problem of backstepping control is avoided.Moreover,the two designed dynamic parameters are dependent on system states rather than a time-varying function,thus the proposed controller is still valid beyond the given fixedtime convergence instant.The effectiveness of the proposed method is demonstrated through two practical systems.展开更多
BACKGROUND In recent years,the mechanical concept of intervertebral disc regeneration has become more and more popular due to the increasing awareness of the importance of preservation of spine movement.Interestingly,...BACKGROUND In recent years,the mechanical concept of intervertebral disc regeneration has become more and more popular due to the increasing awareness of the importance of preservation of spine movement.Interestingly,there is increasing evidence,however,that dynamic stabilization systems may compensate nonphysiological loads,limit pathological movement,normalize disc height and intradiscal pressure,and provide an adaptive environment for disc regeneration.CASE SUMMARY The patient was a 54-year-old man,who presented with a 10-year history of mechanical back pain,which had become progressively serious and radiated into the left lower limb with numbness 3 mo prior.He had decreased muscle strength(class IV)of the left dorsal extensor and plantar flexor.Magnetic resonance imaging scans showed L3-S1 disc degeneration and L4-L5 disc herniation.Because the patient did not respond to various conservative treatments,he underwent a posterior L4-5 discectomy with fixation of the BioFlex dynamic stabilization system(Bio-Spine,Seoul,Korea).Preoperative symptoms were relieved and lumbar function was markedly improved after the operation.L4-L5 disc rehydration of instrumented segment was noted on magnetic resonance imaging at the 2-year follow-up.CONCLUSION Rehydration of the degenerated disc in our patient indicates that the BioFlex dynamic stabilization system may promote disc regeneration.Further research is needed to provide more evidence to support lumbar disc rehydration in the bridged segment using this system.展开更多
文摘Background Coflex, a type of interspinous process implant, can provide intervertebral dynamic stability for surgical segments and effectively relieve lumbocrural pain. However, few studies have described therapeutic strategies and the avoidance of Coflex implant complications. Methods Coflex implant complications in this study included intraoperative or postoperative spinous process fracture, aggravated postoperative lumbocrural pain, dislodgment and malposition. The complications were analyzed, and therapeutic strategies were applied according to the specific complication. The Visual Analogue Scale and Oswestry Disability Index scores were evaluated by using the paired-samples test from SPSS 12.0. Results Conservative treatment was provided to seven patients who experienced aggravated lumbocrural pain even though their devices remained in the correct position, and pedicle screw treatment was used as an alternative in four cases. The Visual Analogue Scale and Oswestry Disability Index scores showed evident improvement in these patients. The Visual Analogue Scale and Oswestry Disability Index scores of two patients who underwent revision were also improved. Conclusions Coflex implants should be avoided in patients with osteoporosis, a narrow interspinous space and intervertebral coronal spondylolysis, or sagittal instability. Furthermore the device choice, depth of implantation, and clamping intensity should be appropriate. Conservative treatment can be provided to patients with symptoms if the device remains in the correct position; however, revisions and salvages should be undertaken with internal fixation of pedicle screws for patients with device malposition, intraoperative implantation failure, or device intolerance.
文摘Dynesys,a pedicle-based dynamic stabilization system,was introduced to overcome some undesirable complications of fusion procedures.Nevertheless,the theoretical advantages of Dynesys over fusion have not been clearly confirmed.The purpose of this editorial was to compare clinical and radiological outcomes of patients who underwent Dynesys system with those who underwent posterior lumbar fusion according to the existing literature and to see if the application of the Dynesys system is superior to the traditional lumbar fusion surgery.According to published clinical reports,the short-term effects of the Dynesys dynamic stabilization system are similar to that of traditional lumbar fusion surgery.Three comparative studies of Dynesys dynamic stabilization and fusion surgery with medium-term follow-up are encouraging.However,the results from four single-treatment-arm and small-sample studies of case series with long-term follow-up were not encouraging.In the present circumstances,it is not possible to conclude that the Dynesys dynamic stabilization system is superior to fusion surgery for lumbar degenerative diseases.
基金supported by the National Natural Science Foundation of China(61821004,U1964207,20221017-10)。
文摘This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two dynamic parameters.Specifically,a set of auxiliary variables is first introduced through state transformation.These variables combine the original system states and the two introduced dynamic parameters,facilitating the closed-loop system stability analyses.Then,the two dynamic parameters are delicately designed by utilizing the Lyapunov method,ensuring that all the closed-loop system states are globally fixed-time stable.Compared with existing results,the“explosion of complexity”problem of backstepping control is avoided.Moreover,the two designed dynamic parameters are dependent on system states rather than a time-varying function,thus the proposed controller is still valid beyond the given fixedtime convergence instant.The effectiveness of the proposed method is demonstrated through two practical systems.
基金Supported by Foundation of Capital Medical Development,Beijing,China,No.2010026.
文摘BACKGROUND In recent years,the mechanical concept of intervertebral disc regeneration has become more and more popular due to the increasing awareness of the importance of preservation of spine movement.Interestingly,there is increasing evidence,however,that dynamic stabilization systems may compensate nonphysiological loads,limit pathological movement,normalize disc height and intradiscal pressure,and provide an adaptive environment for disc regeneration.CASE SUMMARY The patient was a 54-year-old man,who presented with a 10-year history of mechanical back pain,which had become progressively serious and radiated into the left lower limb with numbness 3 mo prior.He had decreased muscle strength(class IV)of the left dorsal extensor and plantar flexor.Magnetic resonance imaging scans showed L3-S1 disc degeneration and L4-L5 disc herniation.Because the patient did not respond to various conservative treatments,he underwent a posterior L4-5 discectomy with fixation of the BioFlex dynamic stabilization system(Bio-Spine,Seoul,Korea).Preoperative symptoms were relieved and lumbar function was markedly improved after the operation.L4-L5 disc rehydration of instrumented segment was noted on magnetic resonance imaging at the 2-year follow-up.CONCLUSION Rehydration of the degenerated disc in our patient indicates that the BioFlex dynamic stabilization system may promote disc regeneration.Further research is needed to provide more evidence to support lumbar disc rehydration in the bridged segment using this system.
