Saggy and dimply knees - what is the best procedure?

I would address the lose skin issue with radiofrequency treatment like Renuvion and also micro-needling and radiofrequency like Secret.

Thank you for your question about addressing sagging knees, particularly as a non-overweight patient. Without pictures, a definitive answer is challenging, but based on your description of the issue, a general approach can be considered.
With age, it's common to experience a loss of muscle and body fat, as well as a reduction in skin collagen and elastin, which can contribute to sagging around the knees. Given this, a thorough physical examination by a qualified plastic surgeon is essential to determine the most appropriate treatment.
There are a couple of surgical options to consider:
Knee Lift (Knee Reduction Surgery): This procedure involves making an incision to remove excess skin and potentially some fat, thereby tightening the area around the knees. The incision can be placed in different ways:
Vertically on the Inside of the Knee: Similar to the inseam on a pair of jeans, this approach may require an incision of about 4 to 6 inches.
Across the Top of the Patella (Kneecap): This approach resembles a horseshoe incision and can effectively address sagging skin around the knee.
These surgical procedures are aimed at permanently eliminating wrinkled skin and can help elevate the neighboring skin for a more tightened and youthful appearance.
Liposuction: While liposuction is primarily used for fat removal, it is not typically effective for tightening skin. As you mentioned not being overweight, liposuction may not be the most suitable option in your case.
Given these considerations, most plastic surgeons would likely recommend a knee lift or reduction, choosing between the vertical or horseshoe incision based on your specific anatomical needs and aesthetic goals.
I hope this information helps clarify the options available for treating sagging skin around the knee area. Consulting with a plastic surgeon who can provide a personalized assessment and recommendation is the next step in exploring these surgical options.
Good luck, and I hope you find a solution that meets your needs and expectations.

I cannot give you much useful information without photographs. If you have excess skin in the front of your knees, there is an a good procedure to help this. If you have extra fat at your middle knees, this response well to tumescent liposuction.