Translating the concept of essence into modern medicine reveals a close relationship with systemic integration, regenerative capacity, and particularly hormonal balance. Rather than a simple wear-and-tear process of aging, osteoarthritis involves complex shifts within the cellular environment of the joint. Cartilage is maintained and rebuilt by chondrocytes; when these cells experience hypofunction, the balance between cartilage breakdown and repair collapses. As pro-inflammatory substances such as pro-inflammatory cytokines, including IL-1 and TNF-α, increase, matrix metalloproteinase activity rises, breaking down cartilage and driving a continuous inflammatory cycle. Donguibogam connects this closely to the roles of the kidney and essence. The kidney corresponds conceptually to the functions of the endocrine system and autonomic nervous system. As we age, declining sex hormones like estrogen and testosterone contribute not only to reduced bone mineral density but also impaired cartilage metabolism. In women, the drop in estrogen after menopause weakens cartilage defense and accelerates joint inflammation, making it a key factor in the rising incidence of osteoarthritis. This parallels the classical view that the depletion of essence weakens the kidney, leading to fragile bones and cartilage. In addition, chronic stress and irregular lifestyle patterns raise stress hormones such as cortisol, which promotes long-term inflammation and impairs tissue regeneration. Circulation is also essential. While cartilage lacks its own blood supply, the subchondral bone beneath it is rich in vessels, directly affecting nutrient delivery and metabolic waste removal. Weakened kidney qi corresponds to circulatory and metabolic hypofunction, which compromises the subchondral bone and indirectly accelerates cartilage loss. Ultimately, osteoarthritis stems from imbalances across metabolism, hormones, and inflammatory regulation, and the Korean medicine approach of replenishing essence and strengthening the kidney aims to restore this whole-body balance.
