Management of Extra-articular Distal Femoral Fractures Through Closed Reduction and Internal Fixation Using Minimally Invasive Plate Osteosynthesis Versus Retrograde Intramedullary Nailing: A Comparative Study.

BACKGROUND

Distal femoral fractures (DFFs) account for a small proportion of femoral fractures and can be challenging to manage. The goal of treatment is to restore alignment, length, and function while minimizing soft-tissue disruption. Two common fixation options are minimally invasive plate osteosynthesis (MIPO) and retrograde intramedullary nailing (RIMN). This study prospectively compared the outcomes of both techniques in extra-articular DFFs.

MATERIALS AND

METHODS

A prospective comparative study was conducted on 40 adult patients with extra-articular DFFs (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association 33-A (AO/OTA 33-A)). Patients were allocated to two treatment groups: MIPO (n = 20) and RIMN (n = 20) according to the surgeon's preference. Outcomes included time to radiological union and range of motion. Functional results were assessed using the Knee Society Score and Lysholm Knee Score at three and six months, and complications were recorded. Statistical analyses were performed using independent t-tests and Fisher's exact test, with significance set at p < 0.05.

RESULTS

Both groups showed significant functional improvement over time. At six months, good-to-excellent results were seen in 80% of MIPO and 85% of RIMN patients. RIMN patients achieved earlier full weight-bearing (average 6.2 weeks vs. 8.3 weeks; mean difference -2.1 weeks (95% CI -2.9 to -1.3; t(38) = -4.65, p < 0.001). and slightly better knee flexion at final follow-up (112° ± 7.5 vs 107° ± 8.2); mean difference 5.0° (95% CI 1.2 to 8.8; t(38) = 2.68, p = 0.011). However, anterior knee pain was more frequently reported after RIMN (20% vs. 5%), although this difference was not statistically significant (p = 0.342). Two superficial infections occurred in the MIPO group (10%). The mean time to union was 14.3 ± 1.9 weeks (MIPO) and 15.1 ± 2.1 weeks (RIMN); the mean difference was -0.8 weeks (95% CI -2.0 to 0.4; t(38) = -1.26, p = 0.214), and no reoperations were required. This prospective study adds focused evidence on extra-articular (AO/OTA 33-A) fractures, which remain underrepresented in comparative research.

CONCLUSIONS

Both MIPO and RIMN are reliable methods for extra-articular DFFs, providing comparable rates of union and excellent functional outcomes. While a broader range of final coronal alignment was observed in the RIMN group, this did not compromise stable union or functional recovery. RIMN offers faster rehabilitation and earlier weight-bearing, but with a higher reported incidence of anterior knee pain. MIPO is associated with lower knee morbidity and may be a suitable alternative, particularly for patients in whom minimizing anterior knee symptoms is a key concern, despite its slower rehabilitation pathway. The choice should be tailored to the fracture pattern, bone quality, and patient needs.