Objective To investigate the effectiveness of arthroscopically assisted treatment of acute tibial insertion avulsion fracture of the posterior cruciate ligament (PCL) via posteromedial incision. Methods Between January 2010 and January 2012, 22 patients with acute tibial insertion avulsion of the PCL underwent arthroscopic reduction and fixation via posteromedial incision. There were 14 males and 8 females with an average age of 32 years (range, 18-48 years). The injury causes included traffic accident injury in 14 cases, sport injury in 4 cases, and falling injury in 4 cases. The disease duration ranged from 7 to 16 days (mean, 10 days). Of 22 patient, 14 had simple PCL injury, 6 had PCL injury with meniscus injury, and 2 with cartilage injury. The results of posterior drawer test were positive in all patients. The preoperative Lysholm score was 51.1 ± 3.4. Results All incisions healed by first intention without infection, deep venous thrombosis of lower limbs, or vessel and nerve injuries. All patients were followed up 12-24 months (mean, 18.4 months). X-ray films showed that all fractures healed with the healing time of 2-4 months (mean, 3 months). The Lysholm score was improved to 96.0 ± 2.2 at 6 months after operation, showing significant difference when compared with preoperative score (t=43.020, P=0.000). Conclusion Arthroscopically assisted treatment of acute tibial insertion avulsion fracture of the PCL via posteromedial incision is a safe, easy, and effective method.