Purpose: To assess the function of the knee joint and the development of post-traumatic arthritis at a minimum of five years after injury in patients in whom an intra-articular distal femoral fracture had been treated with a reamed retrograde intramedullary nail.

Methods: This is a retrospective study of thirty patients with thirty intercondylar-supracondylar femoral fractures treated with a reamed retrograde nailing. According to the AO-ASIF classification, there were 19 (63%) type C1 fractures, and 11 (37%) type C2. Operative technique included reduction of the fracture (closed in 16 cases), minimal internal fixation in all fractures and the insertion of a retrograde interlocked IM nail. Follow up ranged from 61 to 84 months with an average of 66 months. Functional results were assessed using the HSS score and the radiographic appearance of post-traumatic arthritis using the Ahlback score.

Results: Twelve patients (40%) achieved an excellent HSS score and only four (13%) a poor HSS score. Mean flexion of the knee was 113° (from 90° to 130°), and 21(70%) knees had no extension deficit. No correlation was found between the type of fracture and the final score. No radiographic signs of secondary arthritis were recorded only in 5 (17%) fractures.

Conclusions: A high percentage of radiographic post-traumatic arthritis should be expected, after intra-articular femoral fractures were treated with the insertion of a retrograde IM nail. However, because all the objectives of the fracture treatment can be obtained, the functional results remain satisfactory over time.