Femoral shaft reconstruction using tissue-engineered growth of bone.

Tissue engineering is an interdisciplinary field that applies the principles and methods of engineering and the life sciences to the development of biologic substitutes. Bovine periosteum-derived cells were cultivated in vitro, put onto bioresorbable polymer fiber constructs, and allowed to grow until most of the fibers were coated with multiple layers of osteoblasts. Standardized 9-mm nonhealing defects were created in 24 male athymic rats femurs and bridged with titanium miniplates. In 12 animals, the defects were filled with polymer constructs containing periosteum-derived cells (experimental group); in another 12 animals, the defects were either left unfilled (control group I) or filled with polymer templates alone (control group II). After 12-week in vivo implantation, the new bone produced bridged the surgically created defects completely in seven of 10 cases. The animals of the control groups did not show significant bone formation in the gap. Histologic evaluation revealed bone formation in all experimental specimens with rests of cartilage islands showing hypertrophying chondrocytes indicative of enchondral bone formation. Tissue-engineered growth of bone resulted in healing of large segmental bone defects in an orthotopic site in an animal model. The findings of this study support potential applications of the technique of tissue-engineered growth of bone to clinical situations where local bone formation is needed.