From Wolff's law to the Utah paradigm: Insights about bone physiology and its clinical applications

Abstract

Efforts to understand our anatomy and physiology can involve four often overlapping phases. We study what occurs, then how, then ask why, and then seek clinical applications. In that regard, in 1960 views, bone's effector cells (osteoblasts and osteoclasts) worked chiefly to maintain homeostasis under the control of nonmechanical agents, and that physiology had little to do with anatomy, biomechanics, tissue-level things, muscle, and other clinical applications. But it seems later-discovered tissue-level mechanisms and functions (including biomechanical ones, plus muscle) are the true key players in bone physiology, and homeostasis ranks below the mechanical functions. Adding that information to earlier views led to the Utah paradigm of skeletal physiology that combines varied anatomical, clinical, pathological, and basic science evidence and ideas. While it explains in a general way how strong muscles make strong bones and chronically weak muscles make weak ones, and while many anatomists know about the physiology that fact depends on, poor interdisciplinary communication left people in many other specialties unaware of it and its applications. Those applications concern 1.) healing of fractures, osteotomies, and arthrodeses; 2.) criteria that distinguish mechanically competent from incompetent bones; 3.) design criteria that should let load-bearing implants endure; 4.) how to increase bone strength during growth, and how to maintain it afterwards on earth and in microgravity situations in space; 5.) how and why healthy women only lose bone next to marrow during menopause; 6.) why normal bone functions can cause osteopenias; 7.) why whole-bone strength and bone health are different matters; 8.) why falls can cause metaphyseal and diaphyseal fractures of the radius in children, but mainly metaphyseal fractures of that bone in aged adults; 9.) which methods could best evaluate whole-bone strength, "osteopenias" and "osteoporoses"; 10.) and why most "osteoporoses" should not have bone-genetic causes and some could have extraosseous genetic causes. Clinical specialties that currently require this information include orthopaedics, endocrinology, radiology, rheumatology, pediatrics, neurology, nutrition, dentistry, and physical, space and sports medicine. Basic science specialties include absorptiometry, anatomy, anthropology, biochemistry, biomechanics, biophysics, genetics, histology, pathology, pharmacology, and cell and molecular biology. This article reviews our present general understanding of this new bone physiology and some of its clinical applications and implications. It must leave to other times, places, and people the resolution of questions about that new physiology, and to understand the many devils that should lie in its details. (Thompson D'Arcy, 1917). Anat Rec 262: 2001.

Muscle strength and bone in healthy women: effect of age and gonadal status

“…17 Our results further support the hypothesis of a site-specific effect of muscle strength: forces arising from muscular loading and contraction not only influenced BMD but also bone quality and microarchitecture, at least in postmenopausal women. 14,17,[29][30][31][32] Quantitative ultrasound is a validated technique in acquiring information about qualitative and structural features of bone and in identifying individuals at risk for fractures. 20 To our knowledge, this is the first study evaluating the relationship between handgrip strength and qualitative features of bone, both assessed at the upper dominant limb.…”

Three-Dimensional Finite Element Analysis of Maxillary Sinus Floor Augmentation with Optimal Positioning of a Bone Graft Block

“…Based on Peterson's data, a 3D constitutive law describing the macroscopic mechanical behavior of cortical and trabecular bone was defined [25]. As bone is living tissue, the alteration of its structure over time is very important [15,16,26,27]. Changing stress and strain are crucial factors in the healing process after bone fractures or surgery.…”

“…CDF plots serve as a simple method to visualize significant shifts in distribution. Principally the stresses should be below 20 MPa because higher stresses cause resorption of the bone [15,16]. A shift of the CDF curve to the left indicates lower stresses in the augmented bone.…”

Three-Dimensional Finite Element Analysis of Maxillary Sinus Floor Augmentation with Optimal Positioning of a Bone Graft Block

“…Based on Peterson's data, a 3D constitutive law describing the macroscopic mechanical behavior of cortical and trabecular bone was defined [23]. As bone is living tissue, the alteration of its structure over time is very important [24,25,26,27]. Changing stress and strain are crucial factors in the healing process after bone fractures or surgery.…”

“…CDF plots serve as a simple method to visualize significant shifts in distribution. Principally the stresses should be below 20 MPa because higher stresses cause resorption of the bone [24,25]. A shift of the CDF curve to the left indicates lower stresses in the augmented bone.…”