Objective To evaluate the clinical efficacy,safety,and potency ratio of microwave ablation(MW A)combined with percutaneous osteoplasty(POP)for the treatment of flat bone metastases.Methods A total of 57 patients with flat bone metastases complicated by intractable pain,who underwent MWA combined with POP(combination therapy)or only POP(pure POP therapy)at the Zhongshan Municipal People's Hospital of China between January 2016 and January 2023,were enrolled in this study.The combination therapy group had 36 patients and the pure POP therapy group had 21 patients.Visual analog scale(VAS),Oswestry Disability Index(ODI),quality of life assessment scale(QOL)were used to evaluate the preoperative and the postoperative different period efficacy,and the results were compared between the two groups.The procedure-related complications in both groups were recorded.Results The technical success rate in the 57 patients was 100％,and no serious postoperative complications occurred.The mean follow-up time was(4.7±1.3)months(range of 3.4-7.2 months).The preoperative and the postoperative one-day,one-week,one-month and 3-month VAS scores in the combination therapy group were(7.39±1.09)points,(6.53±1.17)points,(1.94±0.70)points,(1.11±0.66)points and(1.39±0.59)points respectively,which in the pure POP therapy group were(7.52±1.01)points,(6.81±0.66)points,(3.38±0.65)points,(2.33±0.56)points and(2.52±0.50)points respectively.One week after operation,the VAS scores in the combination therapy group and the pure POP therapy group were decreased by(5.44±1.32)points and(4.14±0.96)points respectively.The differences in the postoperative one-week(t=-7.62,P＜0.01),one-month(t=-7.28,P＜0.01)and 3-month(t=-7.58,P＜0.01)VAS scores between the two groups were statistically significant.The preoperative and the postoperative one-day,one-week,one-month and 3-month ODI scores in the combination therapy group were(44.33±2.91)points,(44.08±2.82)points,(15.92±3.04)points,(14.00±2.39)points and(16.08±3.61)points respectively,which in the pure POP therapy group were(45.67±3.03)points,(45.14±2.80)points,(22.38±3.09)points,(19.76±2.99)points and(22.10±3.10)points respectively.One week after operation,the ODI score in the combination therapy group was decreased by(28.42±4.23)points,which in the pure POP therapy group was decreased by(23.29±4.28)points.The differences in the postoperative one-week(t=-7.50,P＜0.01),one-month(t=-7.37,P＜0.01)and 3-month(t=-6.51,P＜0.01)ODI scores between the two groups were statistically significant.The preoperative and the postoperative one-day,one-week,one-month and 3-month QOL scores in the combination therapy group were(24.69±3.92)points,(26.06±3.05)points,(38.67±3.00)points,(40.25±3.42)points and(39.58±3.99)points respectively,which in the pure POP therapy group were(24.43±3.53)points,(26.76±3.05)points,(32.81±2.17)points,(33.95±2.68)points and(31.19±4.27)points respectively.One week after operation,the QOL score in the combination therapy group was increased by(13.97±4.88)points,which in the pure POP therapy group was increased by(8.38±4.50)points.The differences in the postoperative one-week(t=8.34,P＜0.01),one-month(t=7.56,P＜0.01)and 3-month(t=7.18,P＜0.01)QOL scores between the two groups were statistically significant.The mean operation cost in the combination therapy group was 10 480.43 Chinese yuan,which was higher than that in the pure POP therapy group.Conclusion For the treatment of flat bone metastases,both pure POP therapy and MWA combined with POP therapy are clinically safe and effective,which can significantly relieve pain and improve quality of life.Compared with pure POP therapy,the MWA combined with POP therapy is more effective but its medical cost is more expensive.