Figure 2. Wrap prototypes were solid CorGlaes-spun, cast-glass tubules, which were typically 20 – 50mm long and 5 – 10mm in diameter with a wall thickness of 1mm. The ends of the damaged nerve were pushed into each end of the tubule and fastened with sutures fed through small holes drilled near the ends of the tubules. The procedure was simple and fast.
Select figure to enlarge.

Construction and characteristics

The essential components of the ‘Wrap’ are Giltech’s CorGlaes® watersoluble glass fiber and a bonding system to allow a web of the fiber to be consolidated as a flexible sheet, which can be easily handled, cut into shapes, folded, and rolled. The solution rate of the water-soluble glass fiber can be adjustable to suit the device specification. Solution rates for the glass range from 0.0005mg.cm-2.hr-1 to 2,500mg. cm-2.hr-1 at 37.5°C in deionized water. The glass formulation(s) can additionally be used for the controlled release of metal ions into the surrounding environment.

The preferred binding materials are the biodegradable polymers including polycaprolactones, polyglycolic acid, polylactic acid, lactide/glycolide copolymers, PHAs (polyhydroxalkanoates), PHBs (polyhydroxbutyrates), LCPs (liquid crystal polymers), and natural materials such as alginates, chitosans, starches, polysaccharides, collagen, skin, milk proteins, and blood components, including platelets.

It is also possible to bond the glass with non-biodegradable polymers such as nylon, polyester, polycarbonate, polypropylene, polyethylene, silicones, polyurethanes, PVC, polymethyl methacrylates, cyanoacrylates, and resin systems. Wrap is normally pre-cut for application, but could be supplied in sheet or roll form or processed into various shapes and forms such as rods, fibers, blocks tubes, or granules.

Its flexibility enables it to be used in repairs where mobility is expected. In sheet form, Wrap can be manipulated to conform to any shape and can be thermoformed with some binders to pre-form shapes of the desired size and contour at the site of use. The solution rate of the Wrap system can be designed to match the application. The glass is wholly inorganic so it carries no rejection or infection risk and does not require donor materials for long gap repairs. Because Wrap dissolves completely it does not cause significant fibrous tissue formation at the repair site. Unlike intubation, Wrap can be used around tissues that have not been completely, divided such as tendons, ligaments, and crush injuries where the local environment requires temporary control.

Wrap is also being considered for many other applications including tendon and ligament repair, orthopaedics, skin equivalents, wound care, dura mater equivalent, hernia slings, and hole patches.