How Sage’s Experience, Agility, and Low-Volume Manufacturing Led to FDA 510(k) Clearance for PAVmed’s Minimally Invasive Carpal Tunnel Surgery Device

PAVmed is a multi-product medical device company with a mission to advance products from concept through commercialization faster and with less capital expense than others in the industry. In 2017, the company was working with a contract medical device manufacturer to develop a disposable, minimally invasive surgical device to treat carpal tunnel syndrome.

The goal of carpal tunnel surgery is to cut the transverse carpal ligament, which relieves compression of the median nerve in the wrist. Traditional carpal tunnel surgery is effective, but invasive, requiring a two-inch long incision. This causes more pain and scarring than a less invasive method would, with recovery taking several weeks to several months or more.

PAVmed’s new device, named CarpX™, would offer an easier, faster, less invasive alternative to traditional carpal tunnel surgery. It would have the potential to reduce postoperative pain and accelerate the patient’s recovery. PAVmed also believed CarpX™ could decrease costs by shifting procedures from the operating room to a less expensive setting.

With CarpX™, a physician would advance a balloon catheter with integrated bipolar radiofrequency (RF) cutting electrodes over a wire under ultrasonic guidance to position it in the carpal tunnel in the wrist. When activated, the balloon would create space within the tunnel, protecting the median nerve from the electrodes and creating stabilizing tension across the transverse carpal ligament. The electrodes would use very short bursts of RF energy to precisely cut the ligament from below, relieving nerve compression without damaging other structures.

In 2018, the device had gone from concept through several design and development iterations into verification and validation testing, where it repeatedly failed due to various design flaws. PAVmed’s manufacturing partner was unable to address the issues quickly enough to meet PAVmed’s aggressive timing and financial goals. Sage was engaged to get the project back on track and deliver what was needed to obtain FDA 510(k) and CE mark approvals for the product.

PAVmed chose Sage for a two key reasons: First, Sage is a lean, flexible company with highly experienced engineers known for their ability to creatively solve complex engineering problems and develop solutions quickly. Additionally, the company has a low-volume manufacturing facility in-house, which is rare in the product development consulting industry and a key differentiator from other firms, most of whom must rely on external contract manufacturers to produce devices for testing.

Most firms that are willing to do low-volume manufacturing are larger companies focused on high-volume contract manufacturing. Rarely do they have the developmental speed, acuity, and creativity embodied in Sage’s team. Sage would be able to quickly and easily produce the limited quantity of devices needed for verification and validation testing, eliminating the dependency on an external contract manufacturer, which would streamline the process and reduce costs.

With the project stalled prior to the design verification and validation phase, Sage needed to move quickly, but it can be difficult to inherit a design that is nearly complete. The team had to gain a thorough understanding of the surgical procedure and the device’s architecture, design intent, and technology before making design changes. They were able to do this quickly because they could rapidly cycle through design, build, and testing iterations in-house.

To optimize the end-to-end process, the engineer responsible for the device’s design and development also acted as the lead for production. This person worked hands-on throughout each stage, managing and iteratively refining the device design and production processes as the team learned. Armed with a thorough understanding of the device and its unique nuances, the lead was able to optimize fixtures and the manufacturing process instead of handing off the design to a contract manufacturer, which often leads to critical learnings being “lost in translation.” Sage’s lead designed and developed assembly fixturing for each manufacturing and assembly step, including unique solutions for a welding fixture that streamlined material bonding and robustness, which were key factors in the performance and efficacy of the CarpX™ device.

As the collective team learned more about the device’s energy and pressure requirements, PAVmed’s technical specifications also evolved, which led to Sage assisting with a software validation to modify the working pressure from 4-8ATM to 2-8ATM. Rather than viewing these changes as time-consuming obstacles, Sage saw them as part of the development process and was adept at building on past learnings to address PAVmed’s changing needs. They were able to iterate collaboratively with PAVmed as the requirements for effective ligament separation evolved throughout the development process.

Through iterative design, manufacturing, and testing, Sage also addressed the issues that had led to earlier failures:

• Reconciling conflicting technology: The proximity of the bipolar energy electrodes to the high-pressure balloon caused the balloon to melt and leak. Sage addressed the issue by adding a thermal barrier between the balloon and the insert-molded electrodes to protect the balloon and improve the firing life of the device.
• Solving activation energy issues: Managing balloon pressure was critical to achieving the right conditions for separating the ligament from the nerve. The results of Sage’s testing led them to change the activation pressure range for the device, resolving activation energy issues.
• Addressing packaging challenges: During ship testing, trays were cracking, and particulate was being generated within them. Sage found that an uncovered device area was rubbing against the packaging and causing the problem. They added a heat shrink barrier on top of the piece to protect it from abrasion and a fortifying packaging insert around the tray to maintain the sterile barrier.

Sage also identified that the existing test plan didn’t adequately represent what the device would experience inside the patient. So, they developed and executed a rigorous testing protocol for over 60 CarpX™ devices in cadavers to evaluate candidate solutions in the proper anatomical context instead of relying on model simulations.

Sage successfully addressed all existing design issues without compromising the integrity of the device. They sped up the development schedule, manufactured the units for verification and validation testing in-house, and achieved successful verification test results on the first round.

PAVmed received FDA 510(k) clearance for its CarpX™ Minimally Invasive Carpal Tunnel Device in April 2020 and CE Mark Certification in May 2021. The first U.S. patient underwent a successful minimally invasive carpal tunnel release using the CarpX™ device in February 2021. Instead of the typical recovery time of months following traditional carpal tunnel surgery, this patient returned to his job as a truck driver in under a week.

Sage’s fast-paced, creative, collaborative culture enabled them to excel in this unique and challenging situation. With a depth and breadth of knowledge and experience, their team welcomes difficult engineering challenges and has a reputation for overcoming them quickly with fast, flexible, iterative approaches in very dynamic environments.