The goal of this research is to compare the effectiveness of arthroscopic TMJ therapy with and without hyaluronic acid (HA) injections in patients with Wilkes stages III and IV. Methods: ClinicalTrials.gov identifier NCT04110587) was a randomized controlled experiment. The 51 patients were split into two groups: those who had TMJ arthroscopy alone (n = 25) and those who underwent TMJ arthroscopy with HA (n = 26). Maximum mouth opening (MMO) and reports of pain in the muscles and joints were assessed at the beginning of therapy, 3, 6, and 12 months later. Both before and during the trial period, disc position was assessed by magnetic resonance imaging. At the start of the research, participants' levels of Oral Health-Related Quality of Life (OHRQoL) were assessed. six months later, and twelve months afterwards. Results: When comparing clinical and radiographic outcomes, neither group differed significantly (P > 0.05). After three to twelve months of observation, the results of using hyaluronic acid as an adjuvant therapy to arthroscopy are negative. OHRQoL was better 6 and 12 months after TMJ arthroscopy. Conclusions: After 3 months of observation, the HA injection performed during TMJ arthroscopy did not seem to have any positive effects.