Bye Bye Saggy Knees! What Does Ultherapy Prime’s FDA-Approval In The USA Mean For The UK

Knees aren’t exactly the first place we think about when it comes to ageing skin, but when they do start to sag, it can be particularly noticeable, confidence-affecting, and tricky to treat, as your knees are constantly moving. There’s plenty of talk about the sagging effect of rapid weight loss on your legs, too, especially with renewed conversations around GLP1 pills. Now, there could be a new non-surgical option to consider: Ultherapy PRIME has just received FDA clearance in the US to improve the appearance of skin laxity on your knees.

So, could a solution for firmer-looking knees be coming to a clinic near you? Here’s your refresher on how exactly Ultherapy PRIME works, and what a US FDA clearance actually means for us here in the UK…

What is Ultherapy PRIME?

Ultherapy PRIME is a non-invasive skin-lifting treatment traditionally used for sagging skin on the face (and you can read about Alice’s own experiences with Ultherapy here). In 2025, it was also approved for use on the décolleté, abdomen and arms. It works by using microfocused ultrasound with real-time visualisation (MFU-V) to deliver precisely targeted energy at different depths beneath the skin (rather than adding volume or physically removing excess tissue). This triggers a wound-healing response that encourages collagen remodelling and elastin production, resulting, over time, in the treated area looking firmer and more lifted.

Ultherapy PRIME is the latest generation of the Ultherapy technology – the world’s number one energy-based device, which has seen four million treatments performed globally. With improvements in the ultrasound visualisation and faster processing, the supercharged device gives practitioners more ability to tailor treatment to an individual’s anatomy, allowing them to treat multiple skin depths, while visualising the treatment area in real time.

So, what’s new?

The big news is that Ultherapy PRIME has now been FDA-cleared in the US to improve the appearance of skin laxity on your knees. According to Merz Aesthetics (the company behind the technology), this makes it the first and only energy-based aesthetic device with an FDA indication specifically for this treatment area.

Importantly, the FDA clearance is currently only for the US market, so technically there aren’t approved treatment protocols for Ultherapy Prime for your knees just yet in the UK. However, having spoken to some leading practitioners, it is a body location that has been treated ‘off label’ by the technology for some time. And, with luck we won’t have long to wait, with Merz Aesthetics stating that a global rollout will follow very shortly.

What results can you expect from Ultherapy PRIME?

One of the biggest attractions of Ultherapy is that it typically involves a single treatment session, is suitable for all skin tones, and doesn’t have a massive amount of downtime (normally just some redness or slight swelling at a maximum). That sets it apart from not only surgical options, but other non-surgical approaches for skin sagging too. It’s also an important consideration when dealing with an active area like the knees as it means you should be able to return to your normal activities very soon afterwards – without any restrictions on movement.

However, the one thing Ultherapy PRIME is not is a ‘quick fix’ treatment. As it relies on stimulating your own collagen production, your skin will gradually become firmer and more taut-looking over the month or so post-treatment; there’s no grand transformation as soon as you step out of the clinic. Your patience is rewarded though, as your full results can then last up to six months.

What practitioners are saying

“I’m really excited about this clearance,” reveals Dr Matt Jarvie-Thomas, from The Cosmetic Skin Clinic in London. “The area above the knee is a common concern for my patients. It’s one of those small areas prone to laxity and crepey skin, particularly in very lean patients or after significant weight loss, and it can really affect people’s confidence and what they feel comfortable wearing. We have treated areas of the body with Ultherapy for many years, so it is fantastic to see some of these uses now being supported by a more defined evidence base, clearer treatment protocols and a formal indication. That gives us a much stronger framework for approaching body treatments with greater precision and consistency.”

What’s next for Ultherapy PRIME?

It isn’t just UK-based approval for a knees protocol that you should be keeping an eye on. Experts predict other areas prone to sagging may be on the horizon too – and that’s great news for anyone not wanting to go ‘under the knife’ any time soon.

“For me, the most exciting part is what this represents for the future,” reveals Dr Jarvie-Thomas. “There are so many areas of the body where patients would love meaningful improvement in skin laxity without surgery. I think we are only beginning to see what Ultherapy PRIME can offer beyond the traditional face and neck indications.”

What to find out more about treatments for your body? Head to the TTG concerns pages for even more targeted solutions.