Treatment of acute triangular fibrocartilage complex (TFCC) tear using arthroscopic suture repair has been used as a general treatment method, but it is difficult to obtain perfect results in all cases. We evaluated clinical and radiologic outcomes of the acute TFCC tear with distal radioulnar joint instability using the arthroscopic suture repair with pronator quadratus (PQ) advancement. Altogether, 80 patients (48 male, 32 female; mean ± SD age, 37.3 ± 11.5 years; mean ± SD follow-up, 23.7 ± 11.4 months) were enrolled in the study. Follow-up was at least 12 months (range, 12-38 months). Patients were divided into group 1 with arthroscopic suture repair alone (34 patients; 17 male, 17 female; mean ± SD age, 35.2 ± 10.8 years; mean ± SD follow-up, 28.1 ± 15.1 months) and group 2 with additional PQ advancement (46 patients; 29 male, 17 female; mean ± SD age, 38.9 ± 11.9 years; mean ± SD follow-up, 18.4 ± 6.2 months), and clinical and radiological assessment was performed. We also compared the ulnar translation of the injured wrist with that of the uninjured wrist using the Push Pull gauge.There was no difference in the range of motion and the grip strength between the 2 groups. However, the disabilities of the arm, shoulder, and hand score (P = 0.042) at 6-month follow-up and disabilities of the arm, shoulder, and hand score (P = 0.015) and patient-rated wrist evaluation score (P = 0.012) at 12-month follow-up were improved in group 2, and patients' satisfaction (P = 0.032) was also higher in group 2. The ulnar translation rate was also improved in group 2 at 6-month follow-up (P = 0.015) and 12-month follow-up (P = 0.045).Arthroscopic suture repair with PQ advancement provided more clinical improvement and proper stability; therefore, it will be an acceptable effective treatment option for acute TFCC tear with distal radioulnar joint instability.