Multicenter trial compares locked plating and retrograde nailing for periprosthetic fractures of the distal femur above TKA

A multicenter trial comparing fixation techniques for periprosthetic fractures of the distal femur above a total knee arthroplasty (TKA) did not find any significant differences in functional outcomes between locked plating (LP) versus retrograde intramedullary nailing (RIMN). However, malunion was significantly more common in the RIMN group, and nonunion and reoperation occurred more often in the LP group (not statistically significant). The researchers concluded that both LP and RIMN are acceptable treatment options for this patient population. These findings were presented at the AAOS 2025 Annual Meeting.

“These injuries are becoming increasingly common with an aging and increasingly active population. They are difficult to treat surgically, and there is a lack of high-level evidence to guide treatment. This study represents the first randomized trial to compare the two most commonly used treatment options: locked plating versus retrograde nailing,” presenting author Aaron Nauth, MD, MSc, assistant professor of orthopaedics at the University of Toronto, told AAOS Now.

The study enrolled 94 patients who were treated at 13 international centers from 2014 to 2022 and randomized them to receive either LP (n = 53) or RIMN (n = 41). The researchers followed up at two weeks, six weeks, three months, six months, 12 months, and 24 months. At the three-month mark, patients completed the Timed Up and Go (TUG) test. The researchers also collected Knee Society Scores (KSS) and rates of nonunion, malunion, reoperation, and mortality. Malunion was defined as a fracture healing with >5 degrees of malalignment in any plane or >1 cm length discrepancy.

Of the total cohort, 82% had follow-up data for analysis. The researchers found no significant differences between groups on the TUG test (56.5 ± 57.0 seconds in the LP group versus 50.0 ± 51.5 seconds in the RIMN group, P = 0.62). The groups also had similar KSS scores.

At one year, 7.5% of patients in the LP group experienced nonunion, compared with 0% of patients in the RIMN group (P = 0.25). Those who received LP were less likely to experience malunion than those who received RIMN (9.3% vs. 36.1%; P = 0.003). The LP group also had more reoperation (12.5% vs. 3.3%). Mortality rates were similar between groups.

“Our initial hypothesis was that locked plating would demonstrate better outcomes than retrograde nailing, but we found the two treatments equivalent with regard to functional outcomes, and the increased reoperation and nonunion rate with locked plating was unexpected,” Dr. Nauth said. He and colleagues are planning a randomized trial of distal femoral replacement versus fixation for the management of these injuries — “another area of huge controversy,” he added.

The authors concluded that orthopaedic surgeons can select to treat these fractures with either locked plating or retrograde nailing based on surgeon preference or specific fracture pattern. “They should be aware of the increased risk of malunion with retrograde nailing and the increased risk of nonunion with locked plating and incorporate strategies to minimize the risk of these complications with each treatment option,” Dr. Nauth added.

Dr. Nauth’s co-authors of “A randomized controlled trial of locked plating versus retrograde nailing for periprosthetic distal femur fractures” are Rosa Park, MD; Michael D. McKee, MD, FAAOS, FRCSC; Jeremy Hall, MD, MEd, FRCS; Amir Khoshbin, MD; Milena Vicente, RN; Matthew Raleigh, MD; Ashmanie Brijmohan; and Emil H. Schemitsch, MD, FAAOS.

Keightley Amen, BA, ELS, is a freelance writer for AAOS Now.