Percutaneous kyphoplasty (PKP) has been used to treat osteoporotic vertebral compression fractures for over 10 years; however, clinically speaking it is still controversial as to whether the use of unipedicular PKP or bipedicular PKP is best. Our study aimed to compare the different effects of unipedicular PKP and bipedicular PKP on the stiffness of compression fractured vertebral bodies (VBs), as well as to assess how cement distribution affect the bilateral biomechanical balance of the VBs. During this study, 30 thoracic VBs were compressed, creating vertebral compression fracture models; then they were augmented by unipedicular (group A and B) PKP and bipedicular (group C) PKP. In group A (unipedicular PKP), the cement was injected into one side and the augmentation was limited to the same side of the VB. In group B (unipedicular PKP), the cement was injected at only one side but the augmentation extended across the midline and filled both sides of the VB. In group C (bipedicular PKP), the cement was injected into both sides and thus achieved the bilateral augmentation. For the unipedicular PKP, the amount of cement injected was 15% of the original VB volume; while in bipedicular PKP, the amount of cement injected was a total of 20% of the original VB volume (10% was injected into each side). Using a MTS-858, we examined three phases of the VBs (intact, pre-augmented, post-augmented), by applying loads axially to the total vertebra and bilateral sides of the vertebra for each of three cycles, respectively. The changes of force and displacement were then recorded and the stiffness of the total vertebra and bilateral sides of the vertebra were calculated. For the pre-augmentation stage, the total VB stiffness of groups A, B and C significantly decreased when the compression fracture models were established (P < 0.05). After the cement augmentation (the post-augmentation stage), both groups A and B, showed that the stiffness could be restored to the initial, intact state; however, in group C, the stiffness was significantly higher than the initial, intact state (P < 0.01). The stiffness of the augmented side of group A was significantly higher than the non-augmented side (P < 0.001). In groups B and C, no significant differences were observed in the stiffness between total VB and each individual side. Thus, we can conclude that both unipedicular PKP and bipedicular PKP significantly increase the total VB stiffness. Bipedicular PKP creates stiffness uniformly across both sides of the vertebrae, while unipedicular PKP, creates a biomechanical balance depending on the distribution of cement. If bone cement is augmented only on one side, the stiffness of non-augmented side will be significantly lower than the augmented side, which might lead to an imbalance of stress on the VB. However, when cement augmentation crosses the midline, stiffness of both sides increase comparatively and biomechanical balance is thus achieved.
BackgroundIn the intensity-modulated radiotherapy (IMRT) era, great improvement has been made in survival of nasopharyngeal carcinoma (NPC). The 7th edition of the International Union against Cancer/American Joint Committee on Cancer (UICC/AJCC) staging system seems “outdated ” as it mainly based on the study in 2D/3D era, and thus the 8th edition has made some amendments according to recent studies. We aimed to compare and evaluate these two editions of staging system for NPC in patients treated with intensity-modulated radiotherapy.MethodsA total of 1317 patients with biopsy-proven, non-metastatic NPC treated with IMRT between 2009 and 2014 at two institutions were retrospectively assessed. All patients were assessed by magnetic resonance imaging and restaged according to the 7th and 8th editions. Prognostic factors for local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), disease-free survival (DFS) and overall survival (OS) were assessed and compared using the Kaplan-Meier method and log-rank test. The Cox proportional hazards model was also used to calculate the hazard ratio (HR).ResultsIn both 7th and 8th edition, insignificant difference could be observed between T2 and T3 disease, T2 and T4 disease (all P > 0.05) for LRFS, while the difference of LRFS between T3 and T4 disease was significant in the previous edition (P = 0.001) but insignificant (P = 0.279) after revision. For OS, highly similar survival curve could be seen between T2 and T3 disease in both edition (all P > 0.1). DMFS and OS were not significantly different between N3a and N1-3b categories of the 7th edition (all P > 0.05). In contrast, obvious segregation was observed between N3 and the other N categories after the revision and combination in the 8th edition (all P < 0.05). DFS and OS were not significantly different between stage IVA and IVB of the 7th edition (P = 0.057 and P = 0.365, respectively); therefore, combining these stages in the 8th edition was reasonable.ConclusionThe overall stages and N categories of the 8th edition of the UICC/AJCC staging system provide better segregation of survival outcomes than the 7th edition. The 8th edition is also more clinically applicable as it has reduced ambiguity and revised out-of-date definitions. However, the T categories need further optimizing as the 8th edition failed to solve the problem of similar survival between adjacent T-classification, which has been exited since 7th edition.
Objective: To analyze the clinical significance of postoperative back muscle exercises after percutaneous vertebroplasty for spinal osteoporotic compression fracture patients. Design: Clinical randomized controlled trials of parallel group nonpharmacologic study. Setting: Patients practised back muscle exercises in the spinal surgery department, rehabilitation department and at their residences. Subjects: Osteoporotic compression fracture patients who had undergone percutaneous vertebroplasty and processed sufficient muscle strength to participate in the training were studied. Interventions: Patients were randomized into two groups, which were titled A and B. General postoperation therapy, including antiosteoporotic medications and education, was offered to all patients. Group B patients received additional systematic back muscle exercise. Main measures: Both Oswestry Disability Index (ODI) and visual analogue scale (VAS) were recorded preoperatively and postoperatively at three-day, one-month, six-month, one-year and two-year follow-up. Results: From January 2006 to January 2009, a total of 82 patients were assessed for eligibility, 60 patients were enrolled and randomized into two groups. Forty-two (70%) patients (20 of 30 in Group A and 22 of 30 in Group B) were successfully followed-up for two years. Systematic back muscle exercises resulted in a significant advantage in both measurements. The ODI of Group B was significantly better than Group A at the six-month, one-year and two-year follow-ups (P < 0.05). The pain level of Group B was significantly lower than in Group A at the one-and two-year follow-ups (P < 0.05). At the end of our study, the mean (SD) of the ODI in Groups A and B were 39.1 (9.14) and 23.4 (5.62); the mean (SD) of the VAS in Groups A and B were 3.4 (1.15) and 2.1 (0.84), respectively. Conclusions: Our findings suggest that the benefit of the exercises required at least six months to be observed; however, the favourable effects could last for two years. Therefore, systematic back muscle exercise should be recommended as one of the treatment guidelines for postpercutaneous vertebroplasty patients.
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