Time to entry point and distal locking of intramedullary nails: a methodological phantom study comparing biplanar and uniplanar surgical imaging

BACKGROUND: Intramedullary nailing is the method of choice for diaphyseal fractures of the femur and tibia and is also commonly used to treat trochanteric hip fractures. Perioperative imaging is essential for visualising adequate reduction, achieving an optimal entry point (EP) and performing distal locking (DL) of intramedullary nails. This methodological study aims to compare biplanar and uniplanar imaging in some steps of intramedullary nailing. METHODS: We used a biplanar preassembled imaging device (Biplanar™ 600s, Swemac Imaging) and a uniplanar imaging device (Ziehm Solo FD, Ziehm Imaging) to measure procedural and radiation times for antegrade and retrograde femoral and antegrade tibial nailing in fully soft flexible tissue encased legs with radiopaque sawbones (SKU:1515–7-11, Sawbones Europe, Malmö, Sweden). Four orthopaedic surgeons with different levels of experience performed all procedures in all three phantoms with both image techniques in random order, producing in total 12 EPs and nailings with DL with each imaging device. Time to EP, radiation times, time to DL for both devices and the number of swings of the uniplanar device for the two procedures were measured. Comparisons between the biplanar and uniplanar systems with a paired-samples t-test were conducted. RESULTS: Using the biplanar device, time to optimal EP was shorter for retrograde femoral (26 s (SD15) vs 35 s (SD13), p = 0.01) and for antegrade tibial nailing (23 s (SD13) vs 49 s (SD24), p = 0.001). No statistically significant differences in time to EP, radiation time or time to DL were found for antegrade femoral nailing. A median of two swings of the uniplanar device was needed to obtain optimal EP for all procedures. CONCLUSIONS: Biplanar imaging slightly but statistically significantly reduced time to EP for retrograde femoral and antegrade tibial nailing in this methodological study comparing biplanar and uniplanar imaging techniques. Biplanar imaging can reduce time and radiation exposure when defining the EP around the knee in intramedullary nailing procedures, but the clinical relevance of these time savings remain to be defined. For antegrade femoral nailing we found no clear benefit with biplanar imaging in the investigated steps of nailing.