I'm still hard and swollen legs especially around knees 4 weeks post op Liposuction. Can I wear spanx garment?

 As a garment will certainly do no harm I would recommend that you where a mild compressive garment such as a Spanx till the gross swelling has subsided. Avoid standing for long periods of time as this will aggravate swelling around and below the knee.

Hello,   You will benefit from a garment or high compression spanx that extends to the ankles and has a proper fit.  Leg elevation when sitting or lying down can also alleviate your discomfort.Please consult with your surgeon as well.

The legs tend to stay the most swollen for the longest time because of gravity.  For my patients I recommend wearing the compression garment for up to 6 weeks if not longer. As long as they prefer.  You should speak with your surgeon to see his preferences.