Suggest Treatment For Weakness In Leg Due To Polio

hello doctor i am 26 year old i have got effected by polio in my left leg when i was 6.Both legs are equal in length but the left leg was 40% weaker than right and i can walk freely without any help only on plain surfaces.i am afraid of falling when my leg bends little bit on harsh(like unequal mud roads) surfaces while walking .main thing is i don't have grip in hip area(left side) and in left knee joint.plz suggest me rgarding my problem(especially about knee joint)