Comparative Analysis of Nail Plate Combination over Alternative Fixation Constructs in Low Energy Distal Femur Fractures: Recovery of Ambulatory Status and Outcomes.

Abstract

To compare ambulatory status, union, mortality, and operative complications in distal femur fracture patients treated with the Nail Plate Combination and alternative fixation constructs. Design: Retrospective Cohort Study. Single Level 1, tertiary referral Academic center. This study included adults with a low-energy distal femur fracture (OTA/AO33A/C and Su 1-3) that received ORIF within 2018-2024. Exclusions were pathologic fractures, antegrade intramedullary devices, and baseline nonambulators (from ambulatory status evaluation only). The primary outcome was ambulatory status at postoperative intervals utilizing Koval-Walking-Score. Secondary outcomes included radiographic union, mortality, and reoperation. 404 patients with a low energy distal femur fracture were included, with 342 included for mobility analysis. Fixation constructs included 189 Nail-Plate-Combination (NPC) (mean age 75.0 ± 10.2, 83.1% female), 118 Lateral Locking Plate (LLP) (mean age 73.4 ± 10.2;, 76.3% female), 79 Retrograde Intramedullary Nail (rIMN) (mean age 73.7 ± 11.1, 74.7% female), and 18 Dual-Plate-Combination (DPC) (mean age 74.6 ± 10.9, 83.3% female) (Age p=0.567, Sex p=0.701). NPC was more frequently selected for Su 2 (56.2%) and Su 3 (65.9%) (p=0.001). NPC demonstrated lower average ambulatory impairment score over LLP: 3-week (-0.8; p=0.002), 6-week (-1.1; p<0.001), and both LLP and rIMN at 3-month (-0.9/-0.8; p=0.049/0.013) and 6-month (-0.9/-0.8; p=0.043/0.021). After Bonferroni correction to account for multiple testing, post hoc pairwise comparisons showed that NPC ambulation scores remained lower at 3 and 6 weeks (-0.8, p=0.024; -1.1, p<0.001). Six-month mortality was lower in NPC than rIMN (9% vs. 19%; p=0.04). DPC showed higher infection (22.2%; p=0.012), wound dehiscence (11.1%; p=0.013), and drainage (5.6%; p<0.001); though sample size limited analysis. Radiographic union was comparable (36.3% vs 52.9% vs 39.6% vs 54.5%, p=0.104). In this study, NPC was associated with superior ambulatory recovery rates to preinjury status over single implant constructs and improved mortality rates over rIMN. Thus, NPC represented a reliable construct for early ambulation and recovery in these injuries. III.