Floating knees: variables affecting bone union and functional outcomes: a retrospective study of 72 cases.

INTRODUCTION

Floating knee involves concomitant and ipsilateral fractures of the femur and tibia, sometimes associated with a patellar fracture. Complications are common, and functional outcomes are often poor. This study aimed to evaluate bone healing and to identify factors influencing nonunion and functional results.

METHODS

This retrospective study included 72 knees, with a mean follow-up of 4.5 years. The primary outcome was bone union. Neurological, vascular and meniscoligamentous injuries were analyzed. Follow-up parameters were clinical, radiological and functional, including the Karlström and Olerud score.

RESULTS

At least one fracture was open in 69% of cases. Mean time to union was 10.5 months for the femur, 7.5 months for the tibia, and 4.4 months for the patella. Nonunion occurred in 68% of femoral fractures, 57% of tibial fractures, and 42% of patellar fractures. Open fractures and tibial vascular injuries were significant predictors of nonunion. Meniscoligamentous injuries were diagnosed in 32% of cases and were more frequent with increasing Ran stage (p = 0.004). Surgical site infection occurred in 30.6% of cases and was significantly associated with open fractures (p < 0.001). Functional outcomes worsened with increasing Ran stage, meniscoligamentous injuries, open fractures, and infection.

CONCLUSION

Floating knee injuries are characterized by prolonged healing, high rates of nonunion and infection, and limited functional outcomes.