https://sites.bu.edu/chenlab/files/2014/01/38_McBeathDevCell_04.pdf

Cell shape, cytoskeletal tension, and rhoa regulate stem cell lineage commitment

Mechanical properties and the hierarchical structure of bone

The biology of fracture healing is a complex biological process that follows specific regenerative patterns and involves changes in the expression of several thousand genes. Although there is still much to be learned to fully comprehend the pathways of bone regeneration, the over-all pathways of both the anatomical and biochemical events have been thoroughly investigated. These efforts have provided a general understanding of how fracture healing occurs. Following the initial trauma, bone heals by either direct intramembranous or indirect fracture healing, which consists of both intramembranous and endochondral bone formation. The most common pathway is indirect healing, since direct bone healing requires an anatomical reduction and rigidly stable conditions, commonly only obtained by open reduction and internal fixation. However, when such conditions are achieved, the direct healing cascade allows the bone structure to immediately regenerate anatomical lamellar bone and the Haversian systems without any remodelling steps necessary. In all other non-stable conditions, bone healing follows a specific biological pathway. It involves an acute inflammatory response including the production and release of several important molecules, and the recruitment of mesenchymal stem cells in order to generate a primary cartilaginous callus. This primary callus later undergoes revascularisation and calcification, and is finally remodelled to fully restore a normal bone structure. In this article we summarise the basic biology of fracture healing.

The biology of fracture healing

Forces in Joints, Skeletal Biology, Analysis of Bone Remodeling, Mechanical Properties of Bone, Fatigue and Fracture Resistance of Bone, Mechanical Adaptation of the Skeleton, Synovial Joint Mechanics, Mechanical Properties of Ligament and Tendon

Skeletal Tissue Mechanics

The still-evolving mechanostat hypothesis for bones inserts tissue-level realities into the former knowledge gap between bone's organ-level and cell-level realities. It concerns load-bearing bones in postnatal free-living bony vertebrates, physiologic bone loading, and how bones adapt their strength to the mechanical loads on them. Voluntary mechanical usage determines most of the postnatal strength of healthy bones in ways that minimize nontraumatic fractures and create a bone-strength safety factor. The mechanostat hypothesis predicts 32 things that occur, including the gross anatomical bone abnormalities in osteogenesis imperfecta; it distinguishes postnatal situations from baseline conditions at birth; it distinguishes bones that carry typical voluntary loads from bones that have other chief functions; and it distinguishes traumatic from nontraumatic fractures. It provides functional definitions of mechanical bone competence, bone quality, osteopenias, and osteoporoses. It includes permissive hormonal and other effects on bones, a marrow mediator mechanism, some limitations of clinical densitometry, a cause of bone "mass" plateaus during treatment, an "adaptational lag" in some children, and some vibration effects on bones. The mechanostat hypothesis may have analogs in nonosseous skeletal organs as well.

Bone's mechanostat: A 2003 update

Das Gesetz der Transformation der Knochen

Ueber die innere Architectur der Knochen und ihre Bedeutung für die Frage vom Knochenwachsthum

This Classic article is a translation and abridgment by M.O. Heller, W.R. Taylor, N. Aslanidis, and Georg N. Duda of the original work by Julius Wolff, Ueber die Innere Architectur der Knochen und ihre Bedeutung fur die Frage vom Knochenwachstum (supplemental materials are available with the online version of CORR). An accompanying biographical sketch on Julius Wolff is available at DOI 10.1007/s11999-010-1258-z. A second Classic article is available at DOI 10.1007/s11999-010-1240-9. An accompanying Editorial is available at DOI 10.1007/s11999-010-1238-3. The Classic Article is ©1870 and is reprinted from Wolff J. Ueber die innere Architectur der Knochen und ihre Bedeutung fur die Frage vom Knochenwachsthum. Virchows Arch Pathol Anat Physiol. 1870;50:389–450.

/pdf/the-classic-on-the-inner-architecture-of-bones-and-its-1hgsu8e240.pdf

The Classic: On the Inner Architecture of Bones and its Importance for Bone Growth

Die vorliegende Arbeit, in welcher die Lehre yon der functionellen Knochengestalt vollst~ndiger, als bisher, yon mir begrfindet werden soll, zerf~illt in die folgenden Kapitel: 1. Die Wechselbeziehungen zwischen Function und dem dieselbe vollziehenden Substrat. 2. Die mathematische Begrfindung der Lehre yon der functionellen Knochengestalt. 3. Die anatomische Begriindung der functionellen Bedeutung pathologischer Knochenformen. 4. Die functionelle Pathogenese der chirurgischen Deformit~ten. 5. Neuer Nachweis der functionellen Bedeutung der pathologisehen Knoehenformen mittelst R~intgendurchstrahlung lebender Individuen. 6. Allgemeinere biologische Bedeutung tier Lehre yon tier functionellen Pathogenese der Deformit~ten. 7. Die anatomische Begrfindung tier functionellen Bedeutung der normalen Knochengestalt. 8. Zusammenstellung und kritische Beleuchtung der verschiedenen neueren Bearbeitungen der Lehre yon der functionellen Knochengestalt.

/pdf/die-lehre-von-der-functionellen-knochengestalt-375k08tm6g.pdf

Die Lehre von der functionellen Knochengestalt

This Classic Article is a reprint of the original work by J. Wolff, On the Significance of the Architecture of the Spongy Substance for the Question of Bone Growth. An accompanying biographical sketch of Georg Hermann von Meyer and his relationship with Dr. Wolff is available at DOI 10.1007/s11999-011-2040-6. The Classic Article is ©1869 and is reprinted from Wolff J. On the significance of the architecture of the spongy substance for the question of bone growth [Ueber die Bedeutung der Architectur der Spongiosen Sunstanz fur de Frage Vom Knochenwachsthu. Vorlaufge Mettheilung]. Centralblatt fur die meichinschen Wissenschaften. 1869;54:849–851.

/pdf/the-classic-on-the-significance-of-the-architecture-of-the-qjg966hnbe.pdf

Julius Wolff

Papers

Das Gesetz der Transformation der Knochen

Ueber die innere Architectur der Knochen und ihre Bedeutung für die Frage vom Knochenwachsthum

The Classic: On the Inner Architecture of Bones and its Importance for Bone Growth

Die Lehre von der functionellen Knochengestalt

The Classic: On the Significance of the Architecture of the Spongy Substance for the Question of Bone Growth: A preliminary publication