Bay Area medtech startup Moximed just raised an impressive $33 million round for its knee implant that preserve joint integrity – particularly for osteoarthritic patients in line for arthroplasty.

The funding will help Moximed gain FDA approval for this KineSpring System, and expand commercial sales in Europe.

The round includes new investors Vertex Venture Holdings, as well as New Enterprise Associates, Glide Healthcare Partners, Morgenthaler Venture and GBA Venture Partners.

Here’s how it works, according to Moximed:

The KineSpring System is a partial load absorber that reduces knee joint load by up to 13 kg. The absorber is implanted in the extra-capsular space along the medial side of the joint, and it is actively unloading the knee during the stance phase of gait. Even more importantly, the KineSpring System is completely joint sparing: since the device is extra-capsular and extra-articular, no bone, ligament, or cartilage is removed. Therefore, the procedure is reversible.

“The clinical benefit of joint unloading is proven to reduce pain,” clinical investigator Philipp Niemeyer of the University of Freiburg said in a statement. “However, while some methods of unloading will transfer the load to other parts of the knee and can actually accelerate OA progression, the KineSpring System has been shown to reduce overall loading on the knee and can be a valuable treatment option.”

The KineSpring System is currently CE marked and is available in some European markets – and has been used in more than 1,000 cases, worldwide. It’s still investigational in the U.S., Moximed says.