What Spirair learned about polydioxanone in its innovative use of the absorbable polymer for a new implant

A new therapy for nasal septal deviation builds on decades of polydioxanone research and development. […]

A new therapy for nasal septal deviation builds on decades of polydioxanone research and development.

By James Kintzing and Dr. Brandon McCutcheon, Spirair

Spirair developed the bioabsorbable SeptAlign implant (shown here with the delivery device) for minimally invasive treatment of nasal septal deviation. [Image courtesy of Spirair]When we founded Spirair and began developing SeptAlign — a novel therapy designed to mechanically correct nasal septal deviation (NSD) — we knew we needed to find a material that could hold the nasal septum under tension long enough for cartilage remodeling but also resorb within an appropriate time frame.

We ultimately chose polydioxanone (PDO), which has been widely used for decades for medtech applications spanning from plastic surgery to orthopedics to cardiology. As we refined SeptAlign and prepared to bring it through clinical research and regulatory review, PDO became a clear choice over many other materials that bring healthcare innovation to life.

The challenge

As co-fellows in the Stanford Biodesign Innovation Fellowship, we spent months in clinical settings observing processes and patient care to identify a list of areas with significant unmet needs. We were drawn to the ear, nose and throat (ENT) specialty, where we observed ENT physicians increasingly using minimally invasive technologies with the potential to broaden the reach of patient care and often enable treatment in the physician’s office rather than the OR.

We discovered that NSD was one of the last areas in the space that did not have a minimally invasive treatment approach, despite being one of the most common problems seen by ENTs.

NSD is one of the most common causes of nasal airway obstruction (NAO), a condition that makes it difficult to breathe through the nose. Nasal airflow is massively impacted by the diameter of the airway. Even a very small deviation in the anterior of the nose where airflow is most restricted can significantly impact nasal breathing. While most people have a deviated septum to some degree and may not require medical intervention, millions of people in the U.S. are symptomatic enough to seek ENT care annually. People with this condition may experience difficulty breathing out of one or both nostrils, headaches, facial pain, nasal congestion, noisy breathing, nosebleeds, chronic sinusitis, snoring and dry mouth.

Traditional septoplasty or septorhinoplasty are the most common open surgical options for NSD. While effective, these procedures are invasive and can require significant downtime, with some patients requiring two weeks or more to recover.

These learnings presented us with an unmet need among people living with NSD and NAO and an opportunity to develop a solution.

Finding the right absorbable polymer

We started imagining how we could effectively correct NSD in a much less invasive way than existing surgical procedures. We thought about this similarly to how a gardener trains a tree or flowers to grow vertically, providing the needed structural support until they can grow upright and flourish on their own. Unlike training trees and flowers, mechanically correcting NSD requires more careful material selection.

We knew we needed a material with appropriate tensile strength, biocompatibility, and a resorption time matching the time needed for the cartilage to heal. It was also important to find a well-characterized material with well-studied mechanism of predictable degradation. The goal with absorbable polymers is to have resorption time match the use case, which requires a careful balance. A mismatch between absorption time and the time needed to heal could increase the risk of complications in this type of procedure.

PLLA (poly-L-lactic acid) and PDLA (poly-D-lactic acid) copolymers have been used in other ENT applications such as lateral wall implants, which support the wall of the nose to prevent lateral wall collapse during breathing. These materials are effective in certain use cases, but we knew they would resorb too slowly for our purposes.

Similarly, poly(DL-lactide-co-glycolide) (PLGA) copolymers have been used successfully in other ENT applications including sinus implants, which are inserted into the sinus opening to maintain patency after sinus surgery. Again, PLGA can be effective in these applications, but we knew that it would resorb too quickly to be an effective material for SeptAlign.

Chosing polydioxanone for a bioabsorbable implant

 After reviewing other materials used in similar applications, we landed on our “Goldilocks” solution and selected polydioxanone (PDO) as the material that would make up SeptAlign’s bioabsorbable implant.

PDO maintains sufficient tensile strength for at least six to 10 weeks, which is also the time required for cartilage remodeling. It also fully resorbs within six months, making it well suited for mechanical correction of NSD.

This material has been used in other applications outside of ENT for decades, including orthopedics, plastic surgery and cardiology. These applications have shown PDO’s safety and efficacy, and we knew we could build on its decades of success by using it in a new way with NSD correction.

Our early clinical research demonstrated that the cartilage can maintain its new shape after being held under tension by absorbable implants. When compared on a weight basis to other polymers commonly used in ENT such as poly(lactic acid) (PLA) and poly(glycolic acid) (PGA), PDO degradation products are less acidic, which could cause less of an inflammatory reaction during resorption.

Looking ahead

Innovation can often be catalyzed by reimagining the familiar. As we look to the future, innovation at Spirair will continue to draw inspiration from everyday materials, methods, and mechanism. SeptAlign received FDA clearance in March 2024, and we are beginning a limited rollout before larger-scale commercialization later this year.

We are looking forward to sharing additional data from our ongoing clinical research and updates on SeptAlign as we bring it to more physicians and patients across the country.

James Kintzing, Spirair co-founder and chief technology officer, is a bioengineer, entrepreneur, and inventor of technologies spanning applications from polymer chemistry to cancer therapeutics to medical devices. He completed the Stanford Biodesign and Innovation Fellowship in 2020.

Dr. Brandon McCutcheon, Spirair co-founder and chief medical officer, is a neurosurgeon, inventor, medical device entrepreneur, and author on over 40 peer reviewed publications. He completed the Stanford Biodesign and Innovation Fellowship in 2020.