What Can Cause Numbness Below The Hips I Had Back Surgery Done About 1 Month Ago And The Pain In The Back Is Gone, But Numbness In The Leg Still?

I had back surgery done about 1 month ago and the pain in the back is gone, but numbness in the leg still? - what can cause numbness below the hips

I had back surgery done on my back. It has been nearly a month, but I still have numbness in his left leg. What is the cause? I go further, it's just that having the ball in the area of the foot is still numb. Someone went through this before. What is the cause of my leg?