Single-Incision Retrograde SIGN Nailing of the Femur and Antegrade SIGN Nailing of the Tibia for a Delayed-Presentation Floating Knee Injury
Donald L. Fejfar, MD¹; Samhita Kadiyala, BA¹; Nikhil Gattu, MD¹; Emily S. Powis, BS¹; Elizabeth Rich, MD²; Ridwan M. Saeed, MD³; Hizkyas Kassaye, MD⁴; Pierre M. Woolley, MD⁵; Bitiel Banda, MD⁶; Kiran J. Agarwal-Harding, MD, MPH^7
1Harvard Global Orthopaedics Collaborative, Boston, MA
²Walter Reed National Military Medical Center, Bethesda, MD
³Muhimbili Orthopaedic Institute, Dar es Salaam, Tanzania
⁴Hawassa University Comprehensive Specialized Hospital, Hawassa, Ethiopia
⁵Hôpital Universitaire La Paix, Port au Prince, Haiti
⁶Mzuzu Central Hospital, Mzuzu, Malawi
⁷Beth Israel Deaconess Medical Center, Boston, MA

Floating knee injury, defined as ipsilateral femoral and tibial shaft fractures, is a high-energy traumatic injury frequently seen following road traffic accidents (RTAs), which disproportionately burden low- and middle-income countries. Definitive treatment of this complex injury typically involves internal fixation, and the commonly accepted preferred method is intramedullary nailing of both fractures. This video article describes the surgical technique for managing a floating knee using retrograde Surgical Implant Generation Network (SIGN) nailing of the femur and antegrade SIGN nailing of the tibia through a single infrapatellar incision in a single anesthesia event.

The case involves a 28-year-old female patient in rural Malawi with a floating knee injury sustained in a motorbike RTA, notable for her delayed presentation of three weeks. The key procedural steps, performed under spinal anesthesia, began with a single infrapatellar incision for the subsequent retrograde nailing of the midshaft femur. Due to delayed presentation (22 days from the date of injury to the first exam in the hospital, with 2 more days before surgery) and callus formation, intraoperative fracture fragment mobilization via a second lateral incision was required before securing the femoral nail. The same infrapatellar incision was then used to perform antegrade nailing of the proximal tibial shaft fracture, which was secured after a closed reduction. This single-incision approach provides a definitive, robust fixation solution appropriate for a resource-constrained setting where challenges include delayed patient presentation and limited imaging infrastructure.