Background Tibial avulsion fractures of the posterior cruciate ligament are not infrequent. Controversies exist between fixation of the fragments and their reconstruction in patients with small bony fragments. This prospective study was undertaken to study the results after fixation of the fragments using a lag screw. Objective This study was designed to evaluate the efficacy of the treatment of posterior cruciate ligament avulsion fractures using the posteromedial approach and fixation with navicular screws. Study design This was a prospective study conducted in 12 patients treated by fixation with navicular screws through the posteromedial approach. Patients and methods From June 2008 to March 2010, 12 patients with acute posterior cruciate ligament avulsion fracture of the tibial attachment were treated surgically at Zagazig University Hospital and Health Insurance Hospital. Nine patients were male and three were female. Navicular screw fixation was used in all 12 patients in avulsed bony fragments, with washers in eight patients and no washers in four patients. Results All the avulsion fractures achieved union at an average of 10–14 weeks. All patients had severe posterior instability (>10 mm) preoperatively. After union of the fracture, no case suffered severe instability. Patients were followed up for an average of 7.58 months (range 6–12 months). Of the 12 patients included in this study, four (33.3%) showed excellent results, seven (58.3%) showed good results, and one (8.3%) showed a fair result. Conclusion The treatment of avulsion fracture of the posterior cruciate ligament by open reduction through the posteromedial approach and internal fixation using partially threaded screws gives very good functional and radiological results. The dissection involved is minimal and risk to the neurovascular structures is negligible.