Objective:To compare the clinical outcomes between modified percutaneous kyphoplasty (PKP) and conventional PKP in the treatment of Kümmell disease.Methods:A retrospective cohort study was conducted of the 57 patients with single level kummell disease who had undergone PKP between January 2015 and December 2017 at Department of Spinal Surgery, Jiangmen Hospital Affiliated to Sun Yat-sen Uni-versity.Of them, 36 received modified PKP and 21 conventional PKP.In the modified PKP group, there were 24 males and 12 females with an age of 73.9 years±9.4 years and a course of disease of 2.2 months±1.5 months; the disease was located at a thorocic vertebra in 20 cases and at a lumbar vertebra in 16.In the conventional PKP group, there were 15 males and 6 females with an age of 72.6 years±11.9 years and a course of disease of 1.8 months±1.1 months; the disease was located at a thorocic vertebra in 10 cases and at a lumbar vertebra in 11.The 2 groups were compared in terms of operation time, bone cement volume, cement leakage, visual analogue scale (VAS), Oswestry disability index (ODI), anterior and middle heights and cobb angle of injured vertebra at postoperative 3 days, 1 and 3 months, and final follow-up.Results:There were no significant differences in the general clinical data between the 2 groups, showing compatibility between groups ( P>0.05).All the operations were accomplished uneventfully with no such serious complications as spinal cord nerve injury, wound infection, pulmonary embolism, bone cement poisoning reaction or death. There was no significant difference between the 2 groups in operation time or bone cement volume ( P>0.05).The rate of cement leakage in the modified PKP group [33.3%(9/27)] was significantly lower than that [52.4%(11/21)] in the conventional PKP group ( P<0.05).There were no significant differences be-tween the 2 groups in VAS, ODI, anterior or middle height of injured vertebra or cobb angle at postoperative 3 days or one month ( P>0.05), but the postoperative values were improved compared to the preoperative ones.At postoperative 3 months and final follow-up, the modified PKP group was significantly better in all the indexes than the conventional PKP group ( P<0.05). Conclusion:Compared with conventional PKP, the modified PKP may lead to better outcomes for Kümmell disease.