Studies specifically isolating nicotine—excluding the thousands of other toxins in cigarette smoke—demonstrate that it is a potent, independent agent that impairs the health and healing of tendons, ligaments, and collagen, largely through vasoconstriction, reduced blood flow, and altered fibroblast function.
Impact on Tendon and Ligament Healing
Impaired Repair Mechanics: Research utilizing subcutaneous nicotine pumps in rat models (simulating human nicotine usage levels) shows that nicotine significantly reduces the maximum load to failure (strength), stiffness, and structural organization of repaired Achilles and rotator cuff tendons.
Reduced Vascularity: Nicotine causes vasoconstriction, reducing blood flow to tissues. This is particularly detrimental to tendons and ligaments, which already have a poor blood supply, as it limits the oxygen and nutrient delivery required for tissue repair.
Decreased Cell Density: Studies on chronic nicotine exposure have shown decreased cell density within the tendon midsubstance, which is associated with degeneration and weaker repair tissue.
Impact on Collagen and Fibroblasts
Altered Collagen Synthesis: Nicotine has been shown to alter the metabolism of fibroblasts, the cells responsible for producing collagen. While some in vitro studies show nicotine may increase collagen production in certain systems, in the context of musculoskeletal, bone-tendon, and wound healing, nicotine generally inhibits proper, organized collagen synthesis.
Fibroblast Dysfunction: Nicotine can inhibit the ability of fibroblasts to properly organize and process collagen (phagocytosis of collagen), leading to less mature, disorganized scar tissue.
Increased Tissue Laxity: Studies indicate that nicotine can alter the material properties of tendons, resulting in decreased stiffness and altered viscoelasticity, which may predispose them to, or perpetuate, tendinopathy.
Key Findings from Non-Cigarette Studies
Vaping/E-Cigarettes: Research has shown that isolated nicotine exposure via vaping can be just as, if not more, detrimental to the biomechanical healing properties of tendons than smoking.
Nicotine Products: The negative impact on healing is present regardless of the delivery method, including nicotine patches, gum, and smokeless tobacco.
Mechanisms of Action
Vasoconstriction: Nicotine causes small blood vessels to narrow, restricting blood flow.
Increased Platelet Stickiness: Nicotine makes platelets stickier, increasing blood viscosity, which further reduces flow through microvessels.
Decreased Oxygen Availability: The reduced flow impairs tissue oxygenation, which is crucial for collagen synthesis.
Inflammation: Chronic nicotine use can cause a prolonged, detrimental inflammatory response during the healing process.
pmc.ncbi.nlm.nih.gov
