Facial inear scars, according to one Morphodynamic perspective, can be considered “Distant Modulators of Facial Dynamics”.
Linear scars are not only localized cutaneous alterations, but persistent biomechanical factors capable of influencing tissues beyond their anatomical borders (Tomasek et al. 2002; Gurtner et al. 2008).
The anisotropic deposition of collagen generates mechanical discontinuities that alter local tension fields, with consequences that propagate at a distance (Aarabi et al. 2007).
In the face, where harmony depends on the balance of muscular vectors and soft tissue dynamics, scars may become long-term determinants of morphologic change (Rohrich 2001, Rizzo 2020).
Mechanobiology of Scarring
Linear scars act as stress lines with positive/negative effects (Gurtner et al., 2008).
Scar tissue exhibits increased stiffness and reduced elasticity compared with normal skin (Silver et al. 2003). Collagen fibers are abnormally aligned, creating stress-shielding and stress-concentration zones (Darby et al. 2014). Cells and tissues in and around scars, mainly muscles, but also fibroblasts and mesenchymal stem cells, sense these alterations through integrins and focal adhesions, activating mechanotransduction pathways that influence gene expression and matrix remodeling (Discher et al. 2005; Ingber 2003), but also altering the normal balance of the complex facial neuromuscular network (Rizzo 2020).
This means that a scar is not an inert structure but a dynamic mechanobiologic stimulus (Hinz 2007).
Distant Effects of Linear Scars
Linear scars act as lines of force, redirecting tissue tension along their axis (Aarabi et al. 2007). A scar that crosses a mimetic muscle modifies its contraction and leads to compensatory hyperactivity of antagonists, producing asymmetry (Zhou et al. 2019) and facial structural changes (Rizzo, 2020).
Scars influence muscular activity, fascial networks and SMAS continuity, creating remote imbalances (Gurtner et al. 2008).
Facelift and blepharoplasty scars are associated with progressive and irreversible morphological changes some years after surgery, not due to iatrogenic errors but to scar-induced force redistribution (Pitanguy 1990; Rohrich 2001, Rizzo 2020).
Mechanobiologic modulation of linear scars
The biological principle that a mechanobiological agent can have both positive and negative effects is commonly known as the “law of homeostasis and hormesis” (or the principle of hormesis: Calabrese 2003).
In biology and physiology, hormesis describes an organism’s biphasic response to a stimulus: mild or moderate (“soft”) stimulation, or for a short time, induces adaptation, regeneration, and strengthening of biological systems; excessive or prolonged stimulation causes damage, inflammation, or degeneration (Engler 2006, Discher 2009, Rizzo,2024).
In other words: “Low (and for short time) doses stimulate, high doses (or prolonged) inhibit or damage”.
“It is a universal principle that applies to many biological fields: mechanobiology, toxicology, exercise, immune response, and tissue regeneration.
From a mechanobiologic perspective, scars are persistent mechanical stimuli (Hinz 2007). Stiffness changes trigger fibroblast-to-myofibroblast differentiation (Tomasek et al. 2002), while stem cells exposed to altered rigidity modify their differentiation pathways (Engler et al. 2006). Over time, this leads to fibrosis, atrophy, or structural disharmony (Wells 2013). Therefore, scars remodel not only locally but also globally, influencing facial dynamics and long-term morphogenesis (Discher et al. 2009).
Clinical Evidence
Upper blepharoplasty can result in narrowing of the palpebral rhyme after several years, due to the scar’s mechanical interference with the levator-aponeurosis–orbicularis system (Matsuo 1994); the eyes may become more sunken, rounder, and the palpebral rhyme becomes smaller. This happens because the scar disrupts the normal neuromuscular network, and the normal dynamics of the eyes cause it to shift downward, dragging the outer part of the eyebrows with it, thus making the look sadder.
Facelift scars are implicated in ear traction and lobe deformity after 4–5 years, explained by tension redistribution along scar vectors (Pitanguy 1990; Rohrich 2001). Even cutaneous scars on the forehead or cheek may modify facial expression symmetry, illustrating the scar’s role as a long-distance mechanical modulator (Zhou et al. 2019). There are various structural changes in the face, changing the natural proportions, but the position of the auricles undergoes evident changes as they migrate downwards and forwards, based on the traction vectors, often increasing in volume and becoming protruding (Rizzo 2020).
Therapeutic Implications
Preventive: alignment of incisions with relaxed skin tension lines (Borges 1984); regenerative biomaterials, PRP, or exosomes to reduce stiffness (Kim et al. 2021).
Early: massage, microneedling, and fractional lasers to improve elasticity (Alster & Tanzi 2003).
Corrective: surgical scar revision, autologous fat grafting (Klinger et al. 2008), Scar treatments and mechanobiologically active threads to rebalance force distribution (Rizzo 2023).
Conclusion
Linear scars should be interpreted as mechanobiologic agents capable of producing distant, progressive, and often underestimated changes in facial morphology. By integrating mechanobiology with Morphodynamic Craniofacial Analysis, clinicians can better understand scars not as static defects but as dynamic elements shaping the face over time (Rizzo 2024).
References
Tomasek JJ, Gabbiani G, Hinz B, Chaponnier C, Brown RA. Myofibroblasts and mechano-regulation of connective tissue remodelling. Nat Rev Mol Cell Biol. 2002;3(5):349-63.
Gurtner GC, Werner S, Barrandon Y, Longaker MT. Wound repair and regeneration. Nature. 2008;453(7193):314-21.
Aarabi S, Bhatt KA, Shi Y, Paterno J, Chang EI, Loh SA, Holmes JW, Longaker MT, Gurtner GC. Mechanical load initiates hypertrophic scar formation through decreased cellular apoptosis. FASEB J. 2007;21(12):3250-61.
Rohrich RJ, Pessa JE. The retaining system of the face: histologic evaluation of the septal boundaries of the subcutaneous fat compartments. Plast Reconstr Surg. 2001;107(1):221-6.
Rizzo, A. Morphodynamic Cosmetic Surgery. Holistic beauty, new paradigms of Aesthetic Surgery. Amazon Self Publishing, 2020.
Calabrese EJ, Baldwin LA. Hormesis: The dose–response revolution. Annu Rev Pharmacol Toxicol. 2003;43:175-197.Mattson MP. Hormesis defined. Aging Res Rev. 2008;7(1):1-7.
Engler AJ, Sen S, Sweeney HL, Discher DE. Matrix elasticity directs stem cell lineage specification. Cell. 2006;126(4):677-689.→ demonstrates that moderate (soft) mechanical stimulation promotes cell differentiation and regeneration, while excessive stiffness or mechanical stress induces damage or fibrosis.
Discher DE, Mooney DJ, Zandstra PW. Growth factors, matrices, and forces combine and control stem cells. Science. 2009;324(5935):1673-1677.
Rizzo A. Mechanobiology and Morphodynamic Cosmetic Surgery: function determines form. Morphodynamic Cosmetic Surgery. 2024.→ highlights how the hormetic principle and cellular mechanoresponse underlie the regenerative and morphodynamic processes of aesthetic-functional tissues.
Hinz B. Formation and function of the myofibroblast during tissue repair. J Invest Dermatol. 2007;127(3):526-37.
Silver FH, Freeman JW, DeVore D. Viscoelastic properties of human skin and processed dermis. Skin Res Technol. 2003;7(1):18-23.
Darby IA, Laverdet B, Bonte F, Desmouliere A. Fibroblasts and myofibroblasts in wound healing. Clin Cosmet Investig Dermatol. 2014;7:301-11.
Discher DE, Janmey P, Wang YL. Tissue cells feel and respond to the stiffness of their substrate. Science. 2005;310(5751):1139-43.Ingber DE. Mechanobiology and diseases of mechanotransduction. Ann Med. 2003;35(8):564-77.
Zhou B, Wang J, Chen Y, et al. Scar contracture alters facial expression dynamics: a biomechanical and clinical analysis. Plast Reconstr Surg. 2019;144(5):1065-75.Pitanguy I. Surgical treatment of facial wrinkles. Clin Plast Surg. 1990;17(1):1-10.
Engler AJ, Sen S, Sweeney HL, Discher DE. Matrix elasticity directs stem cell lineage specification. Cell. 2006;126(4):677-89.Wells RG. Tissue mechanics and fibrosis. Biochim Biophys Acta. 2013;1832(7):884-90.
Discher DE, Mooney DJ, Zandstra PW. Growth factors, matrices, and forces combine and control stem cells. Science. 2009;324(5935):1673-7.
Matsuo K, Hirose T, Takahashi N, Iwasawa M. Long-term changes in eyelid configuration after blepharoplasty. Plast Reconstr Surg. 1994;94(6):944-9.
Borges AF. Relaxed skin tension lines (RSTL) versus other skin lines. Plast Reconstr Surg. 1984;73(1):144-50.
Kim J, Kim H, Jeon J, et al. Exosomes and regenerative medicine: Mechanobiological implications in wound healing. Stem Cells Int. 2021;2021:6697576.Alster TS, Tanzi EL. Hypertrophic scars and keloids: etiology and management. Am J Clin Dermatol. 2003;4(4):235-43.
Klinger M, Marazzi M, Vigo D, Torre M. Fat injection for cases of severe burn outcomes: A new perspective of scar remodeling and reduction. Aesthetic Plast Surg. 2008;32(3):465-9.
Rizzo A. Morphodynamic Cosmetic Surgery: principles of craniofacial dynamics. Chirurgia Cosmetica Morfodinamica. 2023.Rizzo A. Scars as mechanobiologic factors in facial remodeling: clinical perspectives. In press. 2024.
