Can thread lift for the legs work?

Judging from your photos, the area of concern on your knees is relatively small and liposuction alone should do  well in improving the contour.  Liposuction will not lift the skin but will decrease the fullness in the area.  I have never heard of threadlifts for the legs, have never heard it mentioned in a plastic surgery meeting and never seen an article about it published in any plastic surgery journal.  If it truly was effective, then it would be widely known.  The fact that it is so unknown makes it something to be avoided.

Thread lifts may have negative results in the knees. Some of the threads may extrude because of the thin skin and the signficiant mobility of the tissues over the bony prominences when you bend the leg. There might be a greater risk of infection in the knee area and if it happens then the threads would have to be removed.

Thread lifting is a great idea in principle. Ofcourse it would be great to have loose skin managed in this relatively non-invasive way. Unfortunately it simply won't work.....

From your photo, you are pinching the loose skin just above your knee. Liposuction improves localized excess fatty tissue, not loose skin. Whatever fat is there could be partially removed, but this will EMPTY the skin, which usually makes things looser, not tighter! Even with ultrasonic or laser-assisted (Slim-Lipo, etc.) the degree of skin "tightening" is dependent more on your own elasticity than any true collagen shortening response.  From the mid-thigh up (sometimes a bit lower towards the knee) nice improvements can be achieved in the anterior, medial, and lateral thigh, and if there is a bulge of fatty tissue in the medial (inner) knee region, sculpting this area can make the entire leg look slimmer. On top of the knee or just above it, the skin has to have a certain degree of "looseness" so your knee can bend!

Others have made accurate comments about "thread lifting." It doesn't work for the face, and it won't work for your legs either . Just because someone is selling snake oil doesn't mean it works. Make sure you are seeing an experienced plastic surgeon, and if you are, follow his advice!

In most cases, patients who desire a leg "lift" have excess skin that must be removed.  Simple lifting techniques are rarely applicable for this area of the body, and even the smaller surgical procedures are only suitable for patients with small amounts of excess.