Outcomes of Retrograde Intramedullary Nailing Versus Locking Plate Fixation in Distal Femur Fractures: A Systematic Review

Background: Surgical treatment of distal femur fractures has progressed over the years, with decisions guided by factors such as fracture type, pattern, presence of metaphyseal comminution, intra-articular extension, and bone quality. Retrograde intramedullary nails (RIMN) and locking plates (LP) are both commonly used fixation methods for these fractures. However, the question of which approach yields better outcomes remains open, as no consensus has been reached on the optimal treatment. Objective: This systematic review aimed to compare the effectiveness of RIMN versus LP in managing distal femur fractures. Methods: An electronic search was conducted in Medline (PubMed), Embase, and Google Scholar to identify relevant studies published up to July 24, 2024. Studies were included if they compared outcomes of RIMN and LP fixation for acute supracondylar or distal femur fractures (AO/OTA type-33A, B, and C) and reported at least one primary outcome (mean fracture union time, overall complications, implant-related complications, and reoperation rate) or secondary outcome (duration of surgery, intra-operative blood loss, and knee range of motion). Results: Three randomized controlled trials, Three prospective studies, three retrospective studies and one prospective study involving a total of 767 patients (343 treated with RIMN, 424 with LP) were analyzed. This analysis compares locked plating and retrograde intramedullary nailing (rIMN) for distal femur fractures and reveals several key findings. Both methods demonstrate comparable functional outcomes across various scoring systems, with no significant differences in range of motion or recovery; however, rIMN shows advantages in early weight-bearing and quicker union, particularly in less complex fractures. Union rates favor rIMN, with lower nonunion rates (4% to 11.8%) compared to plating (up to 27.5%), though rIMN is associated with more anterior knee pain, while plating has higher infection rates. Operative parameters indicate rIMN involves shorter surgical times and less blood loss, whereas plating provides better stability for complex fractures. rIMN is effective for extra-articular fractures in younger patients, while locked plating is preferable for comminuted and intra-articular fractures in older patients. Overall, both techniques are viable, influenced by fracture type and patient demographics, but the strength of evidence is low due to a lack of randomized controlled trials, underscoring the need for larger studies to bolster these findings. Conclusion: Both retrograde intramedullary nailing and distal femur plating have their respective strengths and limitations. Retrograde nailing may be more advantageous for extra-articular fractures, offering faster recovery and lower nonunion rates, while distal femoral plating is beneficial for complex, intra-articular fractures requiring robust fixation. Further high-quality, prospective studies are recommended to refine indications and optimize outcomes for both techniques in different patient and fracture profilesare viable options depending on patient-specific needs and surgeon preferences.