Treatment of Kümmell’s disease with sequential infusion of bone cement:A retrospective study

BACKGROUND Percutaneous vertebroplasty(PVP)is an effective method for the treatment of neurologically intact Kümmell’s disease,but bone cement leakage during surgery is a problem that deserves attention.AIM To reduce bone cement leakage and evaluate the effect of the sequential infusion of bone cement during PVP for the treatment of stage I or II Kümmell’s disease.METHODS Patients with Kümmell’s disease treated in our hospital from September 2015 to September 2018 were retrospectively analyzed.Patients meeting the inclusion and exclusion criteria were divided into two groups:Traditional single infusion and sequential infusion(SI).The visual analog scale(VAS)and Oswestry disability index(ODI)were evaluated and compared,and duration of operation,bone cement content and complications were recorded.RESULTS Forty-five patients were included in this study;there were 24 in the traditional single infusion group and 21 in the SI group.The VAS and ODI were significantly different for both groups when compared pre-and postoperatively,whereas the differences between 1 wk postoperatively and at the final follow-up were not statistically.When the VAS and ODI of the two groups were compared,there were no significant differences at any time point.The leakage rate of bone cement was significantly lower in the SI group(14.3%,3 of 21)than that in the traditional single infusion group(41.7%,10 of 24).CONCLUSION SI in unipedicular PVP is a safe and effective procedure for neurologically intact Kümmell’s disease,and this technique could decrease the incidence of bone cement leakage.

Influence of angle of attack on a combined opposing jet and platelet transpiration cooling blunt nose in hypersonic vehicle

Flying condition with angle of attack is inevitable in a hypersonic vehicle,and it may influence the thermal protection system(TPS)performance of opposing jet and its combinations.A 3D Navier–Stokes equation and shear stress transfer(SST)k-ωmodel with compressible correction are employed to simulate the angle of attack characteristics of a blunt body with opposing jet and platelet transpiration TPS.The flowfield and heat flux transfer for angles of attack 0°,3°,6°with jet pressure ratio PR=0.1 and 0°,6°,12°with PR=0.2 are obtained.Numerical results show that the flowfield is no longer symmetrical with the effect of the angle of attack.The flowfield and heat transfer in windward and leeward performed adversely.The recompression shock wave in windward is strengthened,which increases local temperature and strengthens heat transfer.The opposing jet fails in thermal protection when the angle of attack reaches critical value;however,the critical angle of attack can be promoted by increasing PR.Finally,the transpiration gas can strengthen the cooling efficiency of windward,thereby,increasing the critical angle of attack.