Principal findings
This study reports the timing of different steps of an intramedullary nailing procedure of the femur or tibia. The main finding of this study is that the use of a biplanar device slightly reduced time to identify EP for tibial nailing and retrograde femoral nailing. A reduction in radiation time was found only in time to EP for the tibia but not for the femur. There was a tendency towards shorter times for DL for both antegrade femur and tibia with uniplanar imaging, although not statistically significantly so, when compared to biplanar imaging.
Agreement and disagreement with the literature
The choice of correct EPs is critical in the stabilisation of femoral or tibial fractures with intramedullary nails. Indeed, failure to identify the right EP can cause fracture malalignment and iatrogenic fracture, such as has been described for lateral femoral nails [1]. Not all EPs are equal, as was shown when comparing fluoroscopy times required for the medial posterior and the lateral anterior trochanteric EP when using the PFNA device [7]. In antegrade femoral nailing trochanteric overhang can obstruct the approach to the piriformis fossa for nail insertion in about 25% of the patients [8]. Additionally, chondral defects in the knee that may be more frequent when using suprapatellar than parapatellar approaches can be avoided using the correct anatomical location of EPs [2].
Although using a uniplanar device, commonly called a C-arm, and manual nail insertion and reaming during intramedullary nailing are clinically the most common method, alternative techniques (e.g., biplanar and robotic devices) have been explored [4, 9]. A combination of fluoroscopy and navigation has been described, but nonorthogonal imaging reduced the accuracy of EP identification, even in the presence of navigation [10].
Strengths and weaknesses in relation to other studies
We sought to investigate whether a biplanar device can reduce the time required to identify adequate EPs and the time for DL during intramedullary nailing of the femur or tibia.
We have not taken preoperative positioning and draping of real patients into consideration in this methodological study. In closed reduction in the fracture table it often takes several swings of the C-arm to confirm reduction. When draping the C-arm, it must swing freely so as not to contaminate the operating field or get stuck and frustrate the surgeon. Biplanar imaging is preassembled and both the reduction manoeuvre and the operating procedure can be performed without repositioning. For DL, the image sources are advanced distally and a fast and reliable technique for DL using biplanar imaging has been widely adopted [6]. Both AP and lateral image sources are draped before the procedure. There is even room for the surgeon to introduce long femoral nails between the patient and the lateral image source.
Our clinical experience is that nail procedures are easier and faster with biplanar imaging, although no objective data supports this, and, to our knowledge, there are no comparative studies to confirm this view. The simultaneous use of two C-arms reduced the number of attempts to achieve optimal pin position in percutaneous pinning of proximal humerus fractures while reducing excess exposures and potential surgical field contamination [11]. In the repair of supracondylar humerus fractures there was no difference in fluoroscopy time or radiation dose for biplanar or uniplanar imaging using one or two C-arms [12]. There was no significant difference in surgery times for slipped capital femoral epiphysis, but the screw positioning was better in the biplanar modus using two C-arms [3]. Both these studies are clinical, comparing surgery times and radiation doses for full procedures. Our methodological study using soft-tissue ensheathed saw bone phantoms examined steps of a full procedure using a preassembled biplanar imaging device compared to a C-arm. When using biplanar imaging, surgeons with different levels of expertise were slightly quicker in locating the EP in the tibia and for retrograde femoral nailing, but differences were small. We found no difference in DL time; however, the time began with the uniplanar device arranged in a perfect lateral position. Such a configuration will introduce swinging of the uniplanar device with sterile drapes that can hinder free movement in the clinical setting. It is also time-consuming to find the correct true lateral projection in order to safely perform DL. Unfortunately, we did not time this set up which would have resulted in longer times for DL and thus be advantageous for the biplanar device in a direct comparison. The use of biplanar imaging for intramedullary nailing of tibia and femur has been recommended to overcome the drawbacks of uniplanar imaging, i.e. time consumption and risks of contamination [4].
The inevitable swinging of the uniplanar C-arm confers an increased risk of surgical field contamination [4, 11]. Contamination of the surgical field was linearly increased with increased cycles/swings of the C-arm with all areas contaminated after 15 cycles in a methodological study using fluorescent powder contaminant [13]. The area closest to the C-arm had the most pronounced contamination. Contamination of C-arm drapes are common, they are correlated to swinging of the C-arm and occur early during procedures [14]. The surgeon-operated mini C-arm showed contamination of the drapes in 70% of the cases [15]. Newer draping techniques of the C-arm compared to older seem to decrease contamination [16, 17]. A future comparative study between uniplanar and biplanar imaging regarding surgical field contamination might be warranted.
Our study's methodological arrangement does not consider the full clinical reality of bleeding and drapes that move while repositioning, becoming immovable when trying to swing back. On the other hand, we found that both techniques work equally reliable in the hands of experienced as well as inexperienced orthopaedic surgeons. DL with biplanar imaging, using the technique described by Granhed in 1998 [6], is fast but requires some practising before the technique is fully understood and works in the surgeon's hands. The wide range of procedural times for DL in the distal femur nicely illustrates this fact.
The total time for the procedure is not fully accounted for by our methodological study measuring procedural steps, given that DL was measured after the C-arm was tilted to the desired lateral position for both the distal femur and the distal tibia. With the biplanar device, one slides it down to the right location and then both AP and lateral images are displayed without much further adjustment. Based on our clinical experience with biplanar imaging, performing two or three DL screws with drilling and inserting the screws is much faster. In this methodological setting we measured the time for only one DL screw for each position.
Biplanar imaging is sometimes criticised for obstructing the surgeon’s range of action in accessing the operating field. The clinical experience is that when nailing the femur and tibia, it is rarely necessary to move the biplanar image sources other than along the extremity. One can preoperatively widen the distance of the lateral image sources to access the proximal femur allowing the reamer and even a long nail to be introduced.
The antegrade femoral nailing in our study was conducted by inserting the PFNA via the tip of the greater trochanter, an EP that is suggested to be advantageous (in terms of fluoroscopy times) over entering via the piriformis fossa [18]. Our choice of a suprapatellar EP for antegrade tibial nailing is consistent with current clinical practice, although this approach can cause cartilage and anterior cruciate ligament defects despite good fluoroscopic control [2]. The suprapatellar approach also results in greater EP accuracy compared to the parapatellar approach [19].
Strengths and weaknesses
One strength of this study is that we used the same sawbones with the same soft tissue envelope to compare times for different steps of the intramedullary nailing procedure. Four surgeons with varying levels of experience performed the procedures in random order and repeated all procedures three times for both image sources. These steps, however, are somewhat synthetic compared to the clinical setting. Furthermore, the need for imaging certain steps is potentially reduced in the not-so-obese sawbones or when there is no bleeding blurring the surgeon’s view. We did not measure a full intramedullary nailing procedure; nor did we take the repositioning into account for total procedural time. The set up for a true lateral projection with the uniplanar device was not timed, which is a drawback for the comparison of times to DL. The number of swings was measured but only for the uniplanar C-arm.
