Dual Construct for Very Low Periprosthetic Distal Femur Fracture-Case Series and Extensile Medial Parapatellar Single Incision Approach.

Background: Owing to the increasing number of arthroplasty cases performed annually and an aging population with longer life expectancy, periprosthetic fractures have become more common. Very low distal femur periprosthetic fractures (PPDFF) are rare and still underreported. Due to the osteopenia bone quality at metaphysis and complex fracture pattern, fixation stability could decline over time especially with single-plate fixation, even with weight-bearing restriction. Dual construct, a newer fixation strategy, not only ensures the most stable fixation but also allows immediate weight bearing in this frail geriatric group. This study aims to demonstrate any change in fracture alignment 1 year after immediate weight-bearing practice post-surgery and to report the fracture union and functional outcomes with the newer dual construct technique.

Method: All Type III Su Classification very low PPDFFs with surgery performed from 2020 to 2023 were reviewed. All surgeries were performed using an extensile medial parapatellar single-incision approach. Either dual plate (DPC) or nail-plate construct (NPC) was performed. Immediate weight bearing was allowed from Day 1 post-surgery. Radiographs were assessed for malunion or non-union. Patients were evaluated for pain, stiffness, functional activity in the WOMAC score, range of knee motion and complications.

Results: Six were performed with DPC and another two with NPC. All patients had union at 8.0 weeks and consolidation at 35 weeks. The differences in LDFA and PDFA were only 1.4° and 1.2°. Post-surgery knee flexion was at a mean of 100°, with a mean WOMAC score of 32 points and Parker Mobility Score of 8. There was no change in ambulatory status and no postoperative complication despite the longer operative time, a mean of 172 min.

Conclusion: A dual construct by dual-plating or nail-plate combination in very low PPDFF ensures fracture fixation stability with early union and allows safe, immediate postoperative weight-bearing as tolerated in older adults.