Articular involvement impacts unplanned reoperation rates in floating knee injuries

To compare the rate of unplanned reoperation to address fracture-related complications between extraarticular floating knee fracture patterns and those involving the articular surface of the knee, and to assess the impact of concomitant patella fracture on outcomes.

Design: Retrospective study of patients with a floating knee injury treated at a single level 1 trauma center from 2012-2022.

Single, urban, level 1 trauma center. Patient selection criteria: Patients ≥18 years old with a floating knee injury treated at a single urban level 1 trauma center from 2012-2022, with at least 3 months of followup. Outcome measures and comparisons: The primary outcome measure was the rate of unplanned reoperation to treat infection, obtain union, or surgically address knee stiffness.

Reoperation to address fracture-related complications was high in both extra and intraarticular floating knee patterns, with a trend toward more surgery to address knee stiffness in those with articular involvement (p = 0.078). Concomitant patella fracture and open fracture were present in 12 and 46 of the 64 patients, respectively; the presence of open fracture was significantly associated with reoperation to address either nonunion or infection (p < 0.001). An associated patella fracture was significantly associated with requiring surgery to address knee stiffness (p = 0.009).

Floating knee injuries with at least one articular fracture, especially when the patella is involved, had higher rates of surgery for knee stiffness. Intraarticular floating knee injuries are challenging, often requiring reoperation for infection, nonunion, or stiffness. Surgeons should be proactive with early motion protocols, supervised therapy, and tools like continuous passive motion to reduce knee stiffness risk.

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