***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Osteoporotic compression fractures ( OVCFs ) commonly occur in aged people , and as much as one-third of these fractures progress to chronic pain .  Kyphoplasty ( KP ) is proved to be efficacious for pain relief and vertebral height restoration in chronic OVCFs , but there is still no data available about the clinical and radiographical outcomes compared by unipedicular and bipedicular KP in treating chronic painful OVCFs . PURPOSE To assess the clinical and radiographical outcomes in treating chronic painful OVCFs compared by unipedicular and bipedicular KP . METHODS Fifty-eight patients with a total of sixty-six chronic painful OVCFs were enroled in our study . They were r and omly allocated into two groups : group I ( n=33 ) was treated with unipedicular KP and group II ( n=25 ) with bipedicular KP . The operation times for each group were recorded and compared . Preoperative and postoperative of visual analogue scores ( VAS ) and oswestry disability index ( ODI ) scores were compared 2 weeks after surgery within each group and between groups . The radiographic outcomes were evaluated by the restoration rate ( RR ) in the most compressed point of the vertebral bodies . RESULTS Significant improvement on the VAS , ODI scores and RR was noted in each group ( p<0.001 ) , and there is no significant difference existing in clinical outcomes between the two groups . The mean operation time for each vertebra in group I was significantly shorter than in group II ( p<0.001 ) . But the RR in group II was higher than in group I ( p=0.041 ) . CONCLUSION Both unipedicular kyphoplasty and bipedicular kyphoplasty can achieve satisfactory clinical and radiographic outcomes in treating the chronic painful OVCFs and the operation time is shorter in unipedicular kyphoplasty . However , the bipedicular kyphoplasty is more efficacious in height restoration Background : Percutaneous vertebroplasty ( PVP ) has been demonstrated to be effective in the treatment of acute osteoporotic vertebral fracture ( AOVF ) . However , the matter of which surgical approach should be selected remains controversial . This research aims to compare the clinical results of unilateral and bilateral PVP for AOVF . Methods : From January 2008 to December 2011 , 68 patients with AOVF were r and omly assigned to the unilateral puncture group ( n=36 ) or the bilateral group ( n=32 ) . These patients underwent percutaneous injection of polymethyl methacrylate into posterior pedicle by the unilateral or bilateral puncture approach .  Visual analogue scale ( VAS ) and the Quality of Life Question naire of the European Foundation for Osteoporosis ( QUALEFFO ) were recorded on presentation , at 1 week , 3 , 6 , and 12 months after operation . The cement leakage was measured by x-ray and computed tomography scan . Results : Follow-up data showed there were no significant differences in VAS and QUALEFFO between 2 groups at 1 week after PVP and only significant difference was observed between 2 groups at 3 , 6 , and 12 months after operation . The cement leakage was 52.7 % in the unilateral puncture group and 28.1 % in the bilateral group . Conclusions : Compared with unilateral puncture , use of bilateral approach during PVP may result in more superior long-term outcomes and less cement leakage for patients with AOVF To assess the immediate efficacy of percutaneous vertebroplasty ( PVP ) in relief of pain and improving mobility of patients with vertebral compression fractures ( VCF ) secondary to osteoporosis , 205 cases ( 175 patients ) underwent 250  percutaneous injections of polymethylmethacrylate ( PMMA ; unilateral , 247 levels ; bilateral , 3 levels ) into vertebrae under CT and fluoroscopic guidance for 34 months . Patients were prospect ively asked to quantify their pain on a visual analog scale ( VAS ) before and a day after PVP . The interval to mobilization was recorded in those who were immobilized because of pain and /or bed-rest therapy ( 115 cases ) . PVP was technically successful in all patients , with three cases of minimal complications . The mean VAS score available for 196 cases was improved from 7.22±1.89 ( range , 3–10 ) to 2.07±1.19 ( range , 0–10 ) by PVP . Ninety-four of 115 immobilized cases ( 81.7 % ) were mobile by 24 h after PVP , and the mean value was 1.9±2.8 days . The incidence of recurrent and new fractures was 15.6 % in 4–25 months ( mean , 15.3 months ) . PVP is a safe and effective treatment for relieving the pain associated with osteoporotic VCF  and strengthening the vertebrae , avoiding refractures . This therapy leads to early mobilization and avoidance of the dangers of conservative therapy of bed-rest OBJECTIVE To evaluate the clinical efficacy of percutaneous bipediculary kyphoplasty with double or single balloon I treatment of osteoporosis vertebral compressive fractures . METHODS Fifty-one patients with painful osteoporotic vertebral compressive fracture involving 69 vertebrae . 19 males and 32 females , aged 72.5 ( 63 - 85 ) , underwent percutaneous kyphoplasty with double inflatable balloon  ( 29 cases , 38 vertebrae ) or single inflatable balloon ( 22 cases , 31 vertebrae ) under X-ray fluoroscopy monitoring . The fractured vertebral bodies were punctuated , balloon was put into the subsided areas and then distended , and bone cement was injected into the cavity . The vertebral height and Cobb angle , preoperative and postoperative , were measured by radiography . Follow-up was conducted for 6 - 12 months . RESULTS All patients tolerated the procedure well with dramatic pain relief within 96 hours after the procedure . No clinical complication was found . Visual analog scale score was improved from 7.8 preoperatively to 2.6 postoperatively ( P < 0.01 ) . Oswestry disability index was decreased from 73 % preoperatively to 26 % postoperatively . In the double balloon group , the heights loss of the anterior and middle portions of the vertebral body reduced from 14.7 mm and 10.5 mm to 10.1 mm and 5.5 mm respectively ( both P < 0.01 ) , and the Cobb angle was corrected from 22.4 degrees to 12.3 degrees ( P < 0.01 ) . In the single balloon group , the heights loss of the anterior and middle portions of the vertebral body reduced from 14.7 mm and 10.6 mm to 10.4 mm and 6.5 mm respectively ( both P < 0.01 ) , and the . Cobb angle was corrected averagely from 21.2 degrees to 11.6 degrees ( P < 0.01 ) . The mean vertebral height restoration rates were 72.8 % and 70.1 % in the double and single balloon groups respectively . The mean Cobb angle correct degrees were 10.1 degrees and 9.5 degrees in double and single balloon groups respectively . There were no significant differences in the average height restoration rate and Cobb angle correction between the double and single balloon groups ( 72.8 % vs 70.1 % , and 10.0 degrees vs 9.5 degrees both P > 0.05 ) . The pain relief and functional recovery were substantial and maintained to the last follow up . CONCLUSION Percutaneous bipediculary kyphoplasty with double or single balloon for painful osteoporotic vertebral body compressive fractures is effective and safe The Scottish Intercollegiate Guidelines Network ( SIGN ) develops evidence based clinical guidelines for the NHS in Scotl and . The key elements of the methodology are ( a ) that guidelines are developed by multidisciplinary groups ; ( b ) they are based on a systematic review of the scientific evidence ; and ( c ) recommendations are explicitly linked to the supporting evidence and grade d according to the strength of that evidence . Until recently , the system for grading guideline recommendations was based on the work of the US Agency for Healthcare Research and Quality ( formerly the Agency for Health Care Policy and Research ) . 1 2 However , experience over more than five years of guideline development led to a growing awareness of this system 's weaknesses . Firstly , the grading system was design ed largely for application to questions of effectiveness , where r and omised controlled trials are accepted as the most robust study design with the least risk of bias in the results . However , in many areas of medical practice r and omised trials may not be practical or ethical to undertake ; and for many questions other types of study design may provide the best evidence . Secondly , guideline development groups often fail to take adequate account of the method ological quality of individual studies and the overall picture presented by a body of evidence rather than individual studies or they fail to apply sufficient judgment to the overall strength of the evidence base and its applicability to the target population of the guideline . Thirdly , guideline users are often not clear about the implication s of the grading system . They misinterpret the grade of recommendation as relating to its importance , rather than to the strength of the supporting evidence , and may therefore fail to give due weight to low grade recommendations . # # # # Summary points A revised system of determining levels of evidence and grade s Purpose To investigate the effect of treatment of multiple myeloma (MM)-associated spinal fracture with percutaneous vertebroplasty ( PVP ) and chemotherapy . Methods Patients with MM-associated spinal fracture were r and omly divided into  combined ( PVP and chemotherapy ) treatment group ( n = 38 ) and single chemotherapy group ( n = 38 ) . For the combined treatment group , bone cement was injected into vertebral body via DSA guided-percutaneous puncture . M2 scheme was used for both groups . And a 5-year follow-up was conducted for the study . Results At the 1-year follow-up visits , PVP combined with chemotherapy achieved complete remission ( CR ) in six patients ( 15.8 % ) ; near complete remission ( nCR ) in ten patients ( 26.30 % ) ; partial remission ( PR ) in nine patients ( 23.7 % ) ; minimal response ( MR ) in three patients ( 7.9 % ) ; no change ( NC ) in four patients ( 10.5 % ) , and disease progression ( DP ) in five patients ( 13.2 % ) . Only chemotherapy alone result ed in 3 CR ( 7.9 % ) ; 8 nCR ( 26.30 % ) ; 19 PR ( 77.5 % ) ; 4 MR ( 17.5 % ) ; 4 NC ( 17.5 % ) , and 2 DP ( 5.0 % ) . While the overall response rate ( ORR ) in the combined treatment group ( 65.8 % ) and the single chemotherapy group ( 50.0 % ) were significantly different , their visual analog pain scales ( 3.01 ± 0.62 and 5.97 ± 0.40 , respectively ) and Karnofsky performance scores ( 89.4 ± 6.3 and 80.3 ± 7.2 , respectively ) were significantly improved after treatment ( P = 0.032 and P = 0.002 , respectively ) . And the ORR between the two groups were significantly different ( P = 0.001 ) . Conclusion Percutaneous vertebroplasty is a minimally invasive surgery for MM-associated pathologic fracture . PVP had the characteristics of minimal trauma , easy operation and less complication . PVP can achieve long-term analgesic effect , and enhance the spinal stability Study Design . A prospect i ve study of patients who underwent multilevel balloon kyphoplasty at a single institute . Objective . To examine and compare the safety and long-term radiographic and clinical effects of unilateral or bilateral balloon kyphoplasty to treat multilevel symptomatic vertebral compression fractures . Summary of Background Data . Typically , balloon kyphoplasty involves placement of inflatable bone tamp via a bilateral transpedicular or extrapedicular approach . Recently , several articles reported unilateral kyphoplasty with comparable outcomes . However , few prospect i ve r and omized study comparing the radiographic and clinical outcomes using unilateral and bilateral approaches was reported . Methods . Forty-nine patients with 114 Osteoporotic vertebral compression fractures were r and omly allocated into two groups adopting unilateral or bilateral balloon kyphoplasty .  Preoperative and postoperative pain scores , back disability , and 36-Item Short Form Health Survey scores were compared with at least a 2-year follow-up . Vertebral body height and vertebral body kyphotic angle from this cohort were analyzed before surgery , after surgery , and at final follow-up . Results . Both unilateral and bilateral balloon kyphoplasty result ed in significant pain reduction and back dysfunction improvement and remained unchanged at final follow-up . Quality of life assessment using 36-Item Short Form Health Survey recorded marked and significant improvements in all mean subscale scores except general health and social function . Regarding the pain reduction , back dysfunction , and 36-Item Short Form Health Survey scores , no significant difference existed between two groups . Significant increases of anterior and middle vertebral heights were recorded for both groups after surgery and maintained for the period of follow-up . The mean correction of vertebr 
    Output:
    
There was no statistically significant difference in visual analog scale , vertebral height , kyphotic angular , and quality of life .
The main operative complications were bone cement leakage and adjacent vertebral fracture , without difference between the two groups .
In view of the current evidence , there is insufficient evidence to show any difference between the unilateral and bilateral approaches in both the PVP and PKP treatment in osteoporotic vertebral compression fractures .