I am not advising the combiflam
as you are asking for safe dosage.
Because for regular treatment its not safe.
But you can use such things of ayurveda which can healful to you for knee pain
as safest way
1. Br. Vaat chintamani ras 1 tab twice a day
2. Rumalaya forte tabelt 2 tabs twice day
3. Maha vishgarbh tail and Br. Sandhvadi tail for massage