Veterans Affairs

Hydrogel tissue expander for bone reconstruction

Shell-free, reshapable, delayed-expansion hydrogel reduces the risk of rupturing sutures

Medical & Biotechnology

This novel medical hardware from the Department of Veterans Affairs has advantageous qualities and is available to health care companies to make, use, or sell publicly.

The hydrogel’s expansion after implantation is demonstrated by this before and after comparison. (VA photo) 

Metal implants are a standard treatment for the replacement of jaws, teeth, ears, noses, and other parts of the face that have been lost due to traumatic injury or disease. Placement of metal implants requires bone for stability integration. When teeth are lost, the mandible and maxilla alveolar bone resorb—a natural phenomenon found in almost every patient – and when this happens there is often not enough bone for the necessary stability of an implant.

Often, bone grafts must be used to replace the lost bone before an implant can be placed. A common problem with the surgical placement of any bone graft (autogenous, allograft, or alloplast) is inadequate soft tissue to close over the bulk of bone graft material.

Presently, the standard of care uses a silicone balloon type of tissue expander. This balloon requires the periodic injection of fluid (usually sterile saline) into a self-sealing valve to increase its volume. A stem with a valve must be made available through the skin or mucosa from the surgical site where the tissue expander is placed. Often the tissue expander must remain in place for weeks to months until the tissue has been sufficiently expanded. Such expanders require multiple injections which are inconvenient and uncomfortable for the patient and increase the risk of infection.

But a VA funded research team has developed (and tested) tissue expanders made of biodegradable, chemically cross-linked hydrogels that are elastic in their dry state. These biocompatible tissue expanders are self-inflating and membrane-free. They swell slowly and elicit minimal negative tissue responses while allowing for rapid and easy manipulation by the surgeon at the time of placement.

These reshapable hydrogel expanders consist of hydrophilic polyethylene glycol (PEG) block and hydrophobic polylactide-co-glycolide (PLGA), which controls the swelling rate. The swelling of the polymer is temporarily slowed by the hydrophobic polyester regions, allowing for the tissue to heal after surgery.

Do you have questions or need more information on a specific technology? Let's talk.

Contact Us