The Tension-Stress effect on the Genesis and Growth of Tissue
by Jon Trister MD
Prolotherapy is a controlled injury of the enthesis.Extravasation of the blood, mechanical injury, and osmotic effects of dextrose lead to activation of multiple physiological systems. These processes take place in the tissues, working simultaneously to control and regulate complex physiological reactions. One such response to injury is the proliferation of fibroblasts and their subsequent transformation into myofibroblasts.These are the key components to mechanical forces.Fibroblasts are the main fascial cells that respond to different types of strain by secreting of proinflammatory cytokines , growth factors and extracellular matrix proteins that enhance proliferation, migration and angiogenesis. These results in stimulating wound healing- cartilages,ligaments, capsules, tendons,muscles, nerves, vessels.
Mechanical forces in the form of needling, osmotic, oncotic , hormonal and chemical stresses, various forms of Osteopathic manipulative treatments induce fibrobalsts strain and subsequently initiate cascade of healing reactions. Magnitude , pattern and duration of the mechanical forces play important role in the induction of the healing expression of the fibrobalsts and are not linear.
Myofibroblasts possess significant contractile abilities, which generate tensile forces at the site of injury (enthesis).
Mechanotransduction is the biological process where cell sense and respond to mechanical load.This process occurs when the body converts mechanical loading into cellular responses.
Long-term medical, biologic and engineering studies have lead to the discovery of a general biologic law governing the stimulation of tissue growth and regeneration: the law of tension-stress. (G. Ilizarov)
Gradual traction on living tissues creates stress that can stimulate and maintain the regeneration and growth of certain tissues. Slow, steady tension of tissue causes them to become metabolically activated, resulting in an increase in their proliferative and biosynthetic functions. These processes are dependent upon two main factors:
1. The quantity and quality of blood supply to the tissue being mechanically stressed and
2. The stimulating effects of tensile forces acting along the lines of muscular contractions because collagen fibers are generally aligned parallel to the vector of tension-stress.
The clinical application of this biologic law has enabled us to manipulate the process of healing soft tissues injuries, and therefore certain diseases and disorders of the musculoskeletal system.
Multiple clinical and scientific observations clearly confirm that the stimulating effect of tension-stress on tissue shares features with the natural process of growth.
Tension-stress stimulates osteogenesis and soft tissue histogenesis. The processes of new tissue formation and growth in adult organisms have many features in common with tissue formation during embryonic and postnatal periods. For example, skeletal muscle, under the influence of myofibroblast-induced tension-stress effects, demonstrate changes in both the energy-supplying (mitochondria) and protein-synthesizing (ribosome, endoplasmic reticulum) systems. Furthermore, smooth muscle lining of blood vessels is also stimulated by tension-stress. Increased smooth muscle biosynthetic activity and proliferation stimulates the formation of new elastic structures and capillary networks needed for successful healing of damaged ligaments and tendons.
Changes similar to those described above also take place in connective tissue of fascia, tendons, dermis, as well as in the endomysium and perimysium of muscle, adventitia of blood vessels, and epineurium and perineurium of major nerve trunks.
During the post-injury period, the numbers of fibroblasts increase and there is marked hypertrophy of the Golgi complex as well as enlargement of the mitochondria, the cytoskeletal microfilaments, and the granular endoplasmic reticulum. Such changes identified the fibroblasts as type II collagenoblasts-cells typical of embryonic connective tissue. Tension-stress also stimulates elongation of nerve axons; eventually, theses processes grow to join one another.
The described processes are not new; different healthcare practitioners use the tension – stress in their practices. Major applications are: Orthopedic surgery, Prolotherapy, Myofascial release, Osteopathy, Massage, Physical therapy. Combining different modalities will improve success rate in the management of patients with various musculoskeletal problems.