The Human Genome Project: implications for the treatment of musculoskeletal disease

Bone's mechanostat: a 2003 update

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.

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

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).

Congenital anomalies: a 25-year overview

Expansion of the discipline of hand surgery and heightened interest in congenital problems have resulted in major advances in the treatment of congenital hand anomalies over the past 25 years. Increased experience with congenital anomalies of the hand has expanded the hand surgeon's knowledge of patterns and relationships between different anomalies resulting in new methods of classification and more logical approaches to treatment. The principles of treatment of the more common anomalies, such as syndactyly, established by prior generations of hand surgeons have been refined in details of technique. New technologies, such as distraction lengthening and free vascularized transfers, have allowed the surgeon to treat new problems and old problems in new ways. In spite of our successes, much remains to challenge hand surgeons in this new millennium, especially in the construction of joints and the expanding field of fetal surgery.

The role of gene therapy. Fact or fiction?

Current research in molecular biology and genetics has dramatically advanced the understanding of the cellular events involved in homeostasis, disease, injury, and healing processes of the tissues of the musculoskeletal system. Recently, genetic predispositions to diseases have been described which offer novel means to address musculoskeletal disorders. Growth factors and cytokines have been identified as key elements in both the injured and healing states. Gene therapy offers an elegant solution to the delivery of therapeutic proteins to the site of disease or injury.