How Threaded Implant Geometry Supports Midfoot Fusion
Orthopedic implants depend on a strong connection between the implant and surrounding bone. Threaded implant geometry is a key part of that connection and influences everything from immediate fixation to long-term durability.
Below is a look at how threaded geometry affects implant performance and what’s next for midfoot fusion technology.
What Is Threaded Implant Geometry?
Threaded implant geometry can help surgical fixation in midfoot fusion by design.
In orthopedic implants, threads are ridged, helical structures along the implant’s surface. The threads enable the implant to engage with the surrounding bone during insertion.
Thread design impacts how an implant fits, fixates, and integrates after surgery. The design is defined by key geometric features, including:
- Thread depth: how pronounced each thread is
- Thread pitch: the spacing between threads
- Thread angle: the shape of each thread
These features influence how efficiently an implant engages bone and maintains fixation over time. When paired with Auxano® technology, this geometry can help reduce surgical complexity and improve patient recovery.
Improving Surgical Fixation One Thread at a Time
Midfoot fusion is a well-established solution for joint pain associated with midfoot arthritis. Implant thread design plays a vital role in delivering sustainable outcomes in this procedure.
Two key considerations for implant thread design are its performance in initial fixation and in load distribution after placement.
Initial Fixation
Initial fixation is a pivotal component of a successful fusion. Yet some common approaches present challenges with stability, ultimately leading to loosening or non-union over time.
Threaded geometry helps address these challenges by embedding within intact, native bone. This enhanced function enables immediate stability and may reduce the need for additional hardware or intraoperative adjustments.
“Some solutions, like trephine dowel arthrodesis, resemble a peg in a hole you tap in. The Auxano® implant uses threads to actively engage the bone,” said Jamey Price, Senior Design Engineer at Auxano® Medical.
Load Distribution
Beyond immediate fixation, how well an implant distributes load after placement is key to long-term health of the fusion site. Many static implant designs may not fully adapt to varying loading conditions or bone anatomies, which can lead to stress concentrations in the implant or stress shielding in the surrounding bone tissue.
Threaded geometry, along with the next-gen features like the adjustable pillar spacing, helps evenly disperse load across the bone-implant interface. Research shows certain geometries, such as discontinuous surface geometry, can help reduce stress concentrations and improve overall stability.
Taking a Well-Designed Approach to Osseointegration
Zooming out, midfoot fusion outcomes depend on how well the implant integrates with surrounding bone. However, not all implant designs support osseointegration in the same way. Some traditional solutions rely on porous features that force bone to grow along disconnected pathways, hindering integrations.
Auxano® technology takes a different approach.
INTREPED® implants are designed with a unique pillared surface. The implant itself is a hollow dowel featuring an Auxano® pillared array arranged in a threaded pattern along its exterior.
This structure supports initial fixation stability, while fenestrations (open pathways through the implant) allow bone to grow from the outside in.
“Auxano® pillar technology allows bone to grow around those pillars in a way that is very easy for the tissue to incorporate,” said Price.
In fact, in vivo studies showed that macro-scale surface morphology promotions bone migration and integration, driven more by surface architecture than by the underlying implant material.
Reducing Surgical Complexity with Geometry
In addition to improving outcomes, threaded geometry also enables smoother surgical workflows in the operating room (OR). the INTREPED® concept follows a simplified drill-tap-insert technique. A fully-loaded surgical kit supports this technique.
Drills and taps in the kit allow surgeons to create a threaded pathway for implant insertion. This simplified procedure also eliminates the need for lengthy joint prep, saving surgeons time in the OR.
As the implant integrates with surrounding bone following surgery, the Auxano® pillared surface helps support how stress is distributed and managed over time.
Shaping Better Patient Outcomes by Design
Advances in implant design are reshaping midfoot fusion, and surgeons are already stepping into the future.
George Quill, MD, FAAOS, has seen the impact of threaded geometry firsthand.
“Auxano® proprietary pillar technology provides immediate fixation for arthrodesis and enhancement of bone formation at the implant-bone interface, ultimately improving surgical outcomes for my patients,” said Quill.
Whether it’s achieving tarsometatarsal or naviculocuneiform fusion, the Auxano® threaded desgin plays a central role in helping surgeons achieve surgical fixation with greater confidence.
Because, ultimately, implant performance isn’t just about material. It’s about geometry.
To learn more about Auxano® proprietary technology, connect with one of our representatives.
Medical Disclaimer
The information provided in this blog is intended for educational and informational purposes only and should not be construed as medical advice, diagnosis, or treatment recommendations. Healthcare professionals should exercise their own clinical judgment when evaluating and treating patients.
Any discussion of medical devices, procedures, or clinical outcomes is general in nature and may not be applicable to all patients or clinical situations. Product performance may vary based on individual patient factors, surgical technique, and adherence to product instructions.
Healthcare providers should consult the applicable Instructions for Use (IFU), product labeling, and relevant clinical guidelines before using any medical device. Patients should seek the advice of a qualified healthcare professional regarding any medical condition or treatment decision.
The views and opinions expressed in this blog are intended to provide general information and do not establish a standard of care or guarantee specific clinical outcomes.
