Citrelock and Citrefix
Next Generation Devices for Tissue Fixation and Anchoring
Problem
Orthopedic and soft tissue reconstruction procedures commonly rely on metal or thermoplastic fixation devices. Despite their widespread use, these implants can introduce complications such as tendon laceration, insertion-related twisting, bulk degradation, and chronic inflammation—factors that may hinder healing and increase the likelihood of revision surgery. Surgeons increasingly seek fixation solutions that deliver the strength required for repair while supporting the body’s natural healing response.
Solution
Both Citrelock™ and Citrefix™ are built on Citregen™, a patented citrate-based biomaterial engineered to mimic the mineral composition of native bone. Citregen™ resorbs in a controlled manner, releasing citrate, calcium, and phosphate to support bone regeneration while minimizing chronic inflammation.
Citrelock™ Tendon Fixation Device System: A resorbable biotenodesis screw designed for tendon fixation across foot, ankle, knee, shoulder, and hand/wrist procedures. Its multi-lead, high-pitch design reduces the number of screw revolutions required during insertion, helping prevent tendon laceration and minimize graft twisting.
Citrefix™ Suture Anchor System: A knotless suture anchor featuring a Citregen™ anchor body and PEEK eyelet. Its tapered, barbed interference-fit design securely attaches soft tissue to bone without the need for knots, simplifying procedures, reducing implant bulk, and supporting more natural tissue healing.
Our citrate biomaterials continue to advance medical innovation and inspire new research in biological sciences and optics.”
— Guillermo Ameer, D.Sc.
Professor, McCormick School of Engineering
Benefits
- Tendon-Friendly Design: Citrelock™ preserves tendon integrity during insertion.
- Controlled Resorption: Both devices degrade predictably, avoiding bulk breakdown and inflammation.
- Enhanced Healing: Citregen™ releases bioactive molecules that stimulate bone regeneration.
- Strong Fixation: Pull-out strength comparable or superior to thermoplastic devices.
- Versatility: Citrelock™ for tendon fixation across multiple joints; Citrefix™ for knotless soft tissue anchoring.
- Simplified Workflow: Citrefix™ eliminates knots, reducing surgical time and complexity.
Technology & Commercialization Status
Citrelock™ and Citrefix™ originated from research conducted in the laboratory of McCormick Professor Guillermo Ameer, where his team pioneered Citregen™, a patented citrate-based biomaterial platform that serves as the foundation for both devices. The development of Citregen™ introduced a novel approach to orthopedic fixation materials, combining bioresorbable properties with the ability to support the body’s natural regenerative processes.
This foundational research laid the groundwork for a new generation of fixation and anchoring technologies designed to provide mechanical strength while promoting biological healing.
Building on this Northwestern-born innovation, Acuitive Technologies, Inc. advanced Citrelock™ and Citrefix™ from the laboratory into clinically ready products. To support global commercialization, Acuitive partnered with Stryker Corporation, one of the world’s leading orthopedic device companies, enabling broader access to these technologies across multiple surgical markets.
Today, both Citrelock™ and Citrefix™ have received FDA 510(k) clearance.
Northwestern Inventor
Guillermo A. Ameer, D.Sc.
Daniel Hale Williams Professor of Biomedical Engineering
McCormick School of Engineering
Feinberg School of Medicine