Floating knee injuries: a retrospective analysis of treatment outcomes and prognostic factors

Floating knee injury is a rare high-energy trauma pattern frequently associated with concomitant organ injuries. Optimal treatment timing and the role of external fixation remain subjects of ongoing debate.

Twenty-one patients who underwent surgery for ipsilateral femoral and tibial fractures were retrospectively reviewed. Fractures were classified using the Fraser and Gustilo-Anderson systems. Functional outcomes were assessed using the Karlström-Olerud criteria.

The mean age was 31 ± 12.1 years; 85% of patients were male. The mean follow-up was 66.6 months. The most common injury mechanism was motorcycle accident (71.4%). According to Karlström criteria, 76.1% of patients achieved excellent or good functional outcomes. External fixation was associated with significantly longer total hospital stay (p = 0.003) and higher superficial infection rates (60.0% vs. 6.3%, p = 0.028) however, this likely reflects greater initial injury severity in patients selected for this approach rather than a direct effect of the device. Patients requiring postoperative ICU admission had significantly higher complication rates (75% vs. 23.1%, p = 0.032). The Injury Severity Score (ISS) correlated significantly with operative time (rs = 0.549, p = 0.010). Delayed definitive surgery was associated with longer total hospital stay (rs = 0.492, p = 0.024) but had no effect on functional outcomes or complication rates. Fraser classification and Gustilo-Anderson grade did not significantly influence functional outcomes.

Floating knee injuries carry significant morbidity despite favourable functional outcomes in the majority of patients. External fixation prolongs hospitalisation and increases infection risk, highlighting the importance of early conversion to definitive fixation in eligible patients. Postoperative ICU admission may serve as a useful indicator for heightened complication risk.