[Outcomes of Retrograde Femoral Nail Osteosynthesis of Intraarticular Fractures of the Distal Femur].

Purpose of the study: Intraarticular fractures of the distal femur rank among the most severe musculoskeletal injuries. Various treatment options, such as plate osteosynthesis or retrograde nailing, can be employed. This study aims to evaluate the clinical outcomes and complications of intraarticular distal femoral fractures treated with retrograde femoral nail, with particular emphasis on C3 fractures.

Material and methods: Between January 2016 and January 2023, 18 AO/33.C3 fractures were treated with a retrograde femoral nail. Of these, two were classified as 33.C1, eight as 33.C2 and eight as 33.C3. Twelve of the fractures were open. After the initial treatment and stabilizing the patient's overall condition, we proceeded with the definitive osteosynthesis. The first phase involved open reduction and fixation using individual screws to reconstruct the articular surface. The second phase consisted in retrograde nailing with correction of the length, axis and rotation of the femur. The evaluation criteria included: complication rate, number of revisions, knee range of motion, mechanical axis and length of the lower extremity, progression of gonarthrosis, pain level, need of walking support, Lysholm and Tegner Activity Score for functional outcome.

Results: Overall, we evaluated the complications and the outcomes of 12 patients (13 fractures). Of these, 8 patients experienced some kind of postoperative complications, primarily insufficient healing or nonunion, which were managed through revision surgery. Plate reosteosynthesis was used in 2 patients who were then excluded from the final clinical evaluation. No cases of deep infection or deep vein thrombosis were reported and no patient required total knee replacement. Seven AO/33.C3 fractures were individually evaluated. The average knee range of motion was nearly 0-93°, maximum flexion was 120°. On average, the lower extremity was 1.6 cm shorter and 7.3° varus to the mechanical axis. Only little progression of gonarthrosis was observed along with low levels of pain. The Lysholm Score ranged between 52 and 84 points (averaging 73.1). The mean Tegner Activity Score was 3.4. All results showed adequate improvement in 33.C2 and 33.C1 groups.

Discussion: The retrograde femoral nail demonstrates several advantages over the locking compression plate, particularly in biomechanical aspects. Various clinical studies have reported superior outcomes in terms of healing, complication rate, blood loss and functional outcome. Our study findings align with some of those international studies, particularly in the rate of infectious complications (0%), mean Lysholm Score (79.3 p.) and Tegner Activity Score (4.1). On the other hand, we observed a higher rate of revision surgery (53.8 %), mainly due to evaluating 33.C fractures only. The main advantage of this method lies in complete visualization, leading to better reconstruction of the articular surface coupled with excellent biomechanical properties of the intramedullary nail.

Conclusions: Intraarticular distal femoral fractures pose significant challenges to treatment and frequently lead to permanent damage. The primary treatment goals involve achieving anatomical reposition of the articular surface, stable osteosynthesis, correction of the femoral length and axis and early rehabilitation. Our study demonstrates good clinical outcomes with a relatively low rate of complications. Patients are capable of walking without pain, achieving a good range of motion, returning to their occupations and becoming self-sufficient. Moreover, there were no infectious complications and no significant progression of gonarthrosis.

Key words: retrograde femoral nail, intraarticular distal femoral fracture, functional outcome, complication rate.