IntroductionAcetylcholinesterase (AChE), a vital component of cholinergic neurotransmission, exhibits various noncholinergic functions. To understand its functional role in degenerative conditions like knee osteoarthritis (KOA), the specific activity of AChE in the synovium of OA knees (grades I-IV) was estimated, and the values were correlated with disease severity. MethodsForty patients with KOA were recruited and categorized into four groups based on the Kellgren-Lawrence classification of KOA as grades I, II, III, and IV, with ten patients in each group. Patient demographic information, including sex, age, pain duration, and visual analog scale (VAS) score, were collected and analyzed, along with the specific activity of synovial fluid AChE. ResultsThe majority of patients with KOA were 41-85 years of age, with a mean age of 64 +/- 8.5 years. The VAS score analysis indicated that as the disease progressed, the pain was significantly higher. The specific activity of AChE in grades I, II, III, and IV was found to be 0.66, 0.98, 0.57, and 0.41 mU/mg of protein, respectively. Among the four grades, grade II KOA showed a significant increase in the AChE activity when compared with other grades of KOA (p < 0.05), followed by grade I. ConclusionOur findings indicate that the increase in AChE activity in KOA grades I and II may facilitate localized inflammation and promote cartilage degeneration in early stages. Therefore, the enzymatic function of AChE can be considered a potential therapeutic target in KOA after validating the finding with larger cohort studies. Key Points center dot Synovial acetylcholinesterase (AChE) activity is elevated in the early stages of Knee Osteoarthritis (KOA). center dot Increased AChE activity in the early stages of KOA suggests its potential role as a mediator of active inflammation and cartilage degeneration. center dot AChE can be considered as a potential therapeutic target in the early stages of joint degenerative conditions like KOA.