Extracorporeal hydroxyapatite-chamber for bone and biomaterial studies.

Hydroxyapatite (HA) spherules and autologous bone (AB) with a central vascular pedicle were housed inside an HA-chamber to form the skeletal segment of specific shape. Experimental chambers were then inserted in a pocket between medial thigh muscles in 13 New Zealand male rabbits for 3 months. Three graft group were scheduled: (A) HA and AB without vascular pedicle, (B) HA with vascular pedicle, (C) HA and AB with vascular pedicle. At term, histology showed tissue and cellular degeneration in group A chambers. Due to spherules coalescence, fibrous tissue is formed in group B chambers. Group C chambers contained living osteocytes in the implanted bone, several newly formed vessels in soft tissue, bone and partial hydroxyapatite erosions. New bone was formed in apposition to both autologous bone and hydroxyapatite. Our study suggests that this experimental model could be used to grow adequately sized vascularized skeletal segments.