Critical Bone Defect Improvement Device and Methods

Customized Treatment for Humans and Canines

At a Glance

Researchers at Colorado State University have developed a novel technique and device for healing large bone defects based on a current standard of care and a bioreplaceable endoprosthetic device to protect and immobilize a highly osteogenic scaffold. With high (70%) porosity, this scaffold integrates with FDA approved fixation plates to accelerate native bone growth. This new method can be used in veterinary or human orthopedic settings, to heal and integrate large bone defects faster, leading to better long-term outcomes.


Critical bone defects occur with unfortunately high frequency in both human and veterinary patients, due to cancer and external trauma. These defects are considered “critical” when they won’t heal spontaneously. Most wounds received by combat veterans are to the extremities, and many are considered “critical” in size. Treatment often involves implanting large metal plates to provide mechanical support for the patient’s lifetime. However, this approach can cause lifelong complications such as discomfort and infection, with complication rates as high as 48% in humans and over 90% in dogs.

Poor healing of these critical bone defects remains one of the biggest challenges in human and veterinary orthopedic medicine, often resulting in reoperations, poor functionality, poor long-term outcomes, and limb loss, causing significant clinical and economic cost.


The CSU group developed a novel method for treating large bone defects that lets the body’s regenerative power grow native bone faster than other known methods. The approach starts with a highly porous, highly osteogenic scaffold. The CSU scaffold is made of anorganic (deproteinized) bone mineral (ABM), which has seen successful clinical use for decades as commercially available bone void fillers (e.g. Bioss®). ABM is naturally replaced by native bone, but it sold as a paste or putty that lacks the porosity and structural integrity required in large defects. The team successfully 3D-prints ABM scaffolds with physical and morphological properties that motivate rapid bone ingrowth in large defects. However, a scaffold alone will not heal a large bone defect. Graft stability, fracture gap size and interfragmentary movement are major mechanical factors in bone growth. Any mobility and fracture gap delays bone growth and reduces the quality of new bone, especially in critical defects. To accommodate these factors, we developed a novel, biodegradable, endoprosthetic “sleeve” (Figure 1) that immobilizes and supports the highly osteogenic ABM scaffold. The sleeve is also 3D printed in a biodegradable medical grade polymer. The sleeve containing the scaffold is fixed to a standard metal fixation plate, creating an endoprosthetic “system”. 3D-printing enables personalization of each endoprosthetic to ensure the best fit in each individual patient.

A controlled pilot study has been completed in sheep, which demonstrated that our endoprosthetic “system” accelerates (1) integration of the scaffold into host-bone at its interface; (2) the maturity of the new bone that forms in the scaffold pores, and (3) the rate of remodeling the scaffold into new bone, faster than other known treatments. These improvements directly translate into faster natural healing, higher weight-bearing sooner and faster patient recovery.

Our goal, now more realistic than ever, is complete, natural bone healing and removal of metal fixation. All our materials are already FDA-approved in similar applications, enabling our method to more easily translate to human orthopedic healthcare. Device designs, material composition and fabrication are proprietary.


  • Faster growth of more mature bone
  • All materials are biodegradable and FDA-approved
  • 3D printing allows for customized fit of the scaffold to patient specific sizing needs
  • All materials are biodegradable and FDA-approved


  • Large bone defect treatment
  • Canine and equine orthopedic treatment
  • Human orthopedic treatment
Last Updated: February 2024
Bone Sleeve

Available for Licensing
TRL: 5


David Prawel
Bernard Seguin
Connor Witt

Reference Number
2021-036 and 2021-063
Licensing Manager

Steve Foster