Clinical efficacy and radiographic K-Rod stabilization for the treatment of multilevel degenerative lumbar spinal stenosis

Background: This study compares the use of radiographic K-Rod dynamic stabilization to the rigid system for the treatment of multisegmental degenerative lumbar spinal stenosis (MDLSS).Methods: A total of 40 patients with MDLSS who underwent surgical treatment using the K-Rod (n=25) and rigid systems (n=15) from March 2013 to March 2017 were assessed. The mean follow-up period was 29.1 months. JOA, ODI, VAS and modified Macnab were assessed. Radiographic evaluations included lumbar lordosis angle, ISR value, operative and proximal adjacent ROM. Changes in intervertebral disc signal were classified according to Pfirrmann grade and UCLA system. Results: JOA, ODI and VAS changed significantly after the operation to comparable levels between the groups. However, the lumbar lordosis significantly decreased at final follow-up between both groups. The ROM of the proximal adjacent segment increased at final follow-up, but the number of fixed segment ROMs in the K-Rod group were significantly lower at the final follow-up than observed prior to the operation. In both groups, the ISR of the proximal adjacent segment decreased, most notably in the rigid group. The ISR of the non-fusion fixed segments in the K-Rod group increased post-operation and during final follow-up. The levels of adjacent segment degeneration were higher in the rigid group vs. the K-Rod group according to modified Pfirrmann grading and the UCLA system. Conclusions: Compared with the rigid system for treatment of MDLSS, dynamic K-Rod stabilization achieves improved radiographic outcomes and improves the mobility of the stabilized segments, minimizing the influence on the proximal adjacent segment.

Clinical efficacy and radiographic K-Rod stabilization for the treatment of multilevel degenerative lumbar spinal stenosis

Background: This study compares the use of radiographic K-Rod dynamic stabilization to the rigid system for the treatment of multisegmental degenerative lumbar spinal stenosis (MDLSS). Methods: A total of 40 patients with MDLSS who underwent surgical treatment using the K-Rod (n=25) and rigid systems (n=15) from March 2013 to March 2017 were assessed. The mean follow-up period was 29.1 months. JOA, ODI, VAS and modified Macnab were assessed. Radiographic evaluations included lumbar lordosis angle, ISR value, operative and proximal adjacent ROM. Changes in intervertebral disc signal were classified according to Pfirrmann grade and UCLA system. Results: JOA, ODI and VAS changed significantly after the operation to comparable levels between the groups. However, the lumbar lordosis significantly decreased at final follow-up between both groups. The ROM of the proximal adjacent segment increased at final follow-up, but the number of fixed segment ROMs in the K-Rod group were significantly lower at the final follow-up than observed prior to the operation. In both groups, the ISR of the proximal adjacent segment decreased, most notably in the rigid group. The ISR of the non-fusion fixed segments in the K-Rod group increased post-operation and during final follow-up. The levels of adjacent segment degeneration were higher in the rigid group vs. the K-Rod group according to modified Pfirrmann grading and the UCLA system. Conclusions: Compared with the rigid system for treatment of MDLSS, dynamic K-Rod stabilization achieves improved radiographic outcomes and improves the mobility of the stabilized segments, minimizing the influence on the proximal adjacent segment.

Rigid group actions on complex tori are projective (after Ekedahl)

In this paper, we give a detailed proof of a result due to Torsten Ekedahl, describing complex tori admitting a rigid group action and showing explicitly their projectivity and their structure in terms of CM-fields. In the appendix, joint with Claudon, we show, using a method of Green-Voisin, that all group actions on complex tori deform to projective ones.

Clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease: a retrospective study

Background: Non-fusion fixation is an effective way to treat lumbar degeneration. The present study evaluated the clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease. Method: Forty-one patients with two-segmental lumbar degenerative disease who underwent surgical treatment by Isobar TTL dynamic stabilization system (n=20) and rigid system (n=21) from January 2013 to June 2017. The mean follow-up period was 23.6 (range 15–37) months. Clinical outcomes were evaluated by oswestry dysfunction index (ODI), visual analogue score (VAS) and modified Macnab. Radiographic evaluations included the height of intervertebral space and range of motion (ROM) of the operative segments and proximal adjacent segment. The intervertebral disc signal change was classified by the modified Pfirrmann grade and University of California at Los Angeles (UCLA) system. Results: The clinical outcomes including the ODI and VAS were significantly improved in two groups after operation, but the difference between two groups was not significant. In addition, the clinical efficacy of modified Macnab in two groups was similar too. Radiologic outcomes include height of intervertebral space, lumbar mobility and intervertebral disc signal. The height of intervertebral space of upper adjacent segments of L2/3 in the rigid group were significantly lower than those in the Isobar TTL group at the last follow-up. Furthermore, the number of fixed segment ROM of L3/4 in Isobar TTL group was significantly lower than pre-operation, suggesting that fixed segment ROMs in Isobar TTL group were limited. And, the ROM of upper adjacent segments of L2/3 in the last follow-up of rigid group increased significantly, while the ROM of L2/3 in Isobar TTL group haven’t changed after operation. At last, the incidence of adjacent segment degeneration was significantly greater in the rigid group than the Isobar TTL group according to modified Pfirrmann grading system and the UCLA system. Conclusion: Isobar TTL system could get a good clinical effect for treatment of two-segmental lumbar degenerative disease. Compared with rigid fixation, Isobar TTL system can get better radiographic outcomes and maintain the mobility of the stabilized segments with less influence on the proximal adjacent segment.

Clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease: a retrospective study

Background:Non-fusion fixation is an effective way to treat lumbar degeneration. The present study evaluated the clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease. Method: Forty-one patients with two-segmental lumbar degenerative disease who underwent surgical treatment by Isobar TTL dynamic stabilization system (n=20) and rigid system (n=21) from January 2013 to June 2017. The mean follow-up period was 23.6 (range 15–37) months. Clinical outcomes were evaluated by oswestry dysfunction index (ODI), visual analogue score (VAS) and modified Macnab. Radiographic evaluations included the height of intervertebral space and range of motion (ROM) of the operative segments and proximal adjacent segment. The intervertebral disc signal change was classified by the modified Pfirrmann grade and University of California at Los Angeles (UCLA) system. Results: The clinical outcomes including the ODI and VAS were significantly improved in two groups after operation, but the difference between two groups was not significant. In addition, the clinical efficacy of modified Macnab in two groups was similar too. Radiologic outcomes include height of intervertebral space, lumbar mobility and intervertebral disc signal. The height of intervertebral space of upper adjacent segments of L2/3 in the rigid group were significantly lower than those in the Isobar TTL group at the last follow-up. Furthermore, the number of fixed segment ROM of L3/4 in Isobar TTL group was significantly lower than pre-operation, suggesting that fixed segment ROMs in Isobar TTL group were limited. And, the ROM of upper adjacent segments of L2/3 in the last follow-up of rigid group increased significantly, while the ROM of L2/3 in Isobar TTL group haven’t changed after operation. At last, the incidence of adjacent segment degeneration was significantly greater in the rigid group than the Isobar TTL group according to modified Pfirrmann grading system and the UCLA system. Conclusion: Isobar TTL system could get a good clinical effect for treatment of two-segmental lumbar degenerative disease. Compared with rigid fixation, Isobar TTL system can get better radiographic outcomes and maintain the mobility of the stabilized segments with less influence on the proximal adjacent segment.

Clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease: a retrospective study

Background: Non-fusion fixation is an effective way to treat lumbar degeneration. The present study evaluated the clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease. Method: Forty-one patients with two-segmental lumbar degenerative disease who underwent surgical treatment by Isobar TTL dynamic stabilization system (n=20) and rigid system (n=21) from January 2013 to June 2017. The mean follow-up period was 23.6 (range 15–37) months. Clinical outcomes were evaluated by oswestry dysfunction index (ODI), visual analogue score (VAS) and modified Macnab. Radiographic evaluations included the height of intervertebral space and range of motion (ROM) of the operative segments and proximal adjacent segment. The intervertebral disc signal change was classified by the modified Pfirrmann grade and University of California at Los Angeles (UCLA) system. Results: The clinical outcomes including the ODI and VAS were significantly improved in two groups after operation, but the difference between two groups was not significant. In addition, the clinical efficacy of modified Macnab in two groups was similar too. Radiologic outcomes include height of intervertebral space, lumbar mobility and intervertebral disc signal. The height of intervertebral space of upper adjacent segments of L2/3 in the rigid group were significantly lower than those in the Isobar TTL group at the last follow-up. Furthermore, the number of fixed segment ROM of L3/4 in Isobar TTL group was significantly lower than pre-operation, suggesting that fixed segment ROMs in Isobar TTL group were limited. And, the ROM of upper adjacent segments of L2/3 in the last follow-up of rigid group increased significantly, while the ROM of L2/3 in Isobar TTL group haven’t changed after operation. At last, the incidence of adjacent segment degeneration was significantly greater in the rigid group than the Isobar TTL group according to modified Pfirrmann grading system and the UCLA system. Conclusion: Isobar TTL system could get a good clinical effect for treatment of two-segmental lumbar degenerative disease. Compared with rigid fixation, Isobar TTL system can get better radiographic outcomes and maintain the mobility of the stabilized segments with less influence on the proximal adjacent segment.

FLEXIBLE RINGS IN COMPARISON WITH RIGID RINGS IN THE TREATMENT OF FUNCTIONAL TRICUSPID INSUFFICIENCY: TWO DIFFERENT MODELS OF REVERSE REMODELING OF THE RIGHT HEART

Objective. To compare the models of reverse remodeling of the right heart after the tricuspid valve repair with rigid or flexible rings.Material and Methods. During the period from September, 2016 to February, 2018, 308 patients who had indications for intervention on the mitral valve and concomitant tricuspid insufficiency without significant differences in clinical status were randomized into two groups. Patients of both groups underwent intervention on the mitral valve with concomitant tricuspid valve repair by a rigid ring (Rigid group, n=154) or a flexible ring (Flex group, n=154)Results. The perioperative mortality rates were 2.0% in the Rigid group and 2.5% in the Flex group (p=0.504). There was no difference in the pacemaker implantation rate (5.1% vs. 2.6%, p=0.238). Freedom from tricuspid insufficiency recurrence at 12 months follow-up was comparable (96.7% in the Rigid group vs 96.1% in the Flex group, p=0.521). The global systolic function of the right ventricle (fractional change in area, FAC; ejection fraction, EF) significantly increased in both groups (p<0.001 for both group) without significant intergroup differences (p=0.231 for FAC; p=0.156 for EF). Intergroup comparison of the regional systolic function (systolic excursion tricuspid valve, TAPSE; longitudinal velocity of the tricuspid valve, S’) showed that patients of the Flex group had significantly higher increases in the parameters (p<0.001 for TAPSE; p=0.002 for S’).Conclusion. Both types of the devises had low rates of recurrence of tricuspid insufficiency at the midterm follow-up and contributed to the restoration of the global systolic function of the right ventricle. However, the rigid rings due to their design fix the tricuspid valve annulus, which inevitably affects the regional systolic function. In perspective, the flexible rings can function without interfering with the restoration of the natural shape of the tricuspid valve annulus and its uniform contraction during the cardiac cycle, thus ensuring a significant increase in regional systolic function.

Characterization of finitely generated groups by types

In this paper we show that all finitely generated nilpotent, metabelian, polycyclic, and rigid (hence free solvable) groups [Formula: see text] are fully characterized in the class of all groups by the set [Formula: see text] of types realized in [Formula: see text]. Furthermore, it turns out that these groups [Formula: see text] are fully characterized already by some particular rather restricted fragments of the types from [Formula: see text]. In particular, every finitely generated nilpotent group is completely defined by its [Formula: see text]-types, while a finitely generated rigid group is completely defined by its [Formula: see text]-types, and a finitely generated metabelian or polycyclic group is completely defined by its [Formula: see text]-types. We have similar results for some non-solvable groups: free, surface, and free Burnside groups, though they mostly serve as illustrations of general techniques or provide some counterexamples.