Regeneration of amputated avian bone by a coral skeletal implant

Bone fractures are common in both wild and captive birds (1, 2). Avian bones are thin and brittle and tend to break into fragments or shatter upon a variety of natural events (midair collisions, fights with other animals; ref. 2) or anthropogenic experiences (wounding by gunfire, collisions with cars or fences, encounters with traps, attacks by dogs or cats, etc.; ref 1). The prospect of full recovery following repair of avian bone fracture is often poor, and the complication rate is high (3). For wild birds, anything less than complete normal function cannot be regarded as successful, and slight malunion or a change in a few degrees of rotation can produce a severe loss of flight function (4). Furthermore, in nomadic species, time is critical because long periods of rehabilitation may prevent the birds from reuniting with their flocks. In experiments with implantation of fragments of skeleton from the coral Stylophora pistillata, we found the implants to be avian osteo-conductive biomaterial, acting as a scaffold for a direct osteoblastic deposition. In the case study presented here, the bird regained complete flight activity within 2 weeks after surgery, with full regeneration of the amputated ulna.