Accurate calibration of tibial intramedullary nail opening

The opening of the intramedullary nail is crucial to the success or failure of the entire surgery, and sometimes we even spend more time on the opening because there are numerous examples of opening causing surgical failure. On the coronal plane, a deviation of the needle insertion point from the outside can cause inversion deformity, while a deviation of the needle insertion point from the inside can cause inversion deformity; Advancing the needle point too far forward in the sagittal plane can lead to anterior convexity deformity. Some people have asked if the needle point is too far backward, but generally not, it is determined by anatomy. (Figure 1-1.2.3)

Figure 1-1

Figure 1-2

Figure 1-3

Where exactly is this opening? Once the guidelines are put online, many doctors may become uncertain.

One complication of intramedullary nails is damage to the meniscus and articular cartilage, and the best way to avoid this risk is to have precise needle insertion points. There is an anatomical bare area (as shown in Figure 2) or safe zone at the anterior edge of the proximal tibia.

Figure 2

What is the size of this bare area, which is about 1-3cm wide? This is the long side, and the short side is even smaller. It shouldn't be difficult to cut open and see this position directly. In recent years, the suprapatellar approach has been increasingly accepted by a large number of doctors. However, when performing the suprapatellar approach, the needle insertion point is not visible and relies on fluoroscopy.

So the question is, where is the needle insertion point? In the upright position, on the medial slope of the lateral intercondylar ridge, and in the lateral position, on the anterior edge of the articular surface. (Figure 3)

Figure 3

It is not difficult to see that this positioning point is still very accurate. So the next question is, will the position of the tibia affect our judgment of the needle insertion point? The answer is yes, in fact, there are already corresponding articles that elaborate on this issue. (Figure 4)

Figure 4

The author conducted an experiment where the correct needle insertion point was in the neutral position. If the tibia was rotated inward or outward, the false impression displayed was that the needle insertion point was not good and needed to be adjusted. So, we not only need to know where the correct needle insertion point is, but also the position of the tibia when obtaining this correct position.