Download Chapter 11: Skeletal Healing

Chapter 11: Skeletal Healing
Michael Zuscik and
Regis J. O’Keefe
From the Primer on the Metabolic Bone Diseases
and Disorders of Mineral Metabolism, 7th Edition.
www.asbmrprimer.org
Figure 1
Figure 1 Tissue morphogenesis during bone repair. (A) Periosteum is a well-microvascularized tissue (vessels in black) consisting of
an outer fibrous layer and an inner cambium layer. The cambium layer contains abundant stem/progenitor cells that can differentiate
into bone and cartilage. (B) After fracture or osteotomy, blood supply is disrupted at the defect, and a blood clot (hematoma) forms
near the disjunction. (C) Progenitor cells residing in the periosteum are recruited to differentiate into osteoblasts to facilitate
intramembraneous bone formation where intact blood supply is preserved and chondrocytes to facilitate endochondral bone
formation adjacent to the fracture where the tissue is hypoxic. In this panel, osteogenic tissue is labeled (1) with newly mineralized
tissue labeled (2). Tissues supporting chondrogenesis are labeled (3). (D) Intramembraneous bone formation proceeds with robust
matrix mineralization (1) where blood supply is present distal to the fracture site. Endochondral bone formation proceeds
simultaneously with chondrogenic tissue supporting a growing population of chondrocytes that comprise the hypertrophic cartilage
which is labeled (4). (E) Cartilage tissue continues to mature, ultimately encompassing the callus nearest the fracture site.
Revascularization of the callus also ensues. (F) Chondrocytes in the hypertrophic cartilage undergo terminal differentiation and the
matrix is progressively mineralized expanding the portion of the callus that is comprised of woven bone. (G) The remodeling process
proceeds with osteoclasts and osteoblasts facilitating the conversion of woven bone into lamellar bone, culminating in the recreation of the appropriate anatomic shape.
© 2008 American Society for Bone and Mineral Research