Chapter 2401 - 2341: Precisely Aligned
First of all, you need to understand the anatomical structure of the human body: the heart, mediastinum, great vessels, thymus and so on, a good part of them are hidden behind the sternum. In other words, if you want to avoid this big rock of a sternum that’s blocking the way and still do the operation, it’s basically impossible. Splitting the sternum is better than taking a detour and snapping who-knows-how-many other bones; the front of the chest isn’t "nothing but the sternum and no other bones." And this approach is also the fastest: once you split the sternum, you can quickly expose the heart, mediastinum, great vessels and other vital organs. Since you’ve chosen an open-chest surgery, the first priority is to make sure the surgical field is wide, bright, and clear, so the doctors can work neatly and finish the operation as soon as possible. This is like choosing a midline abdominal incision when you need to explore the abdominal cavity: both the chest cavity and abdominal cavity can be imagined as burlap sacks—one cut right down the middle, and it’s easiest to see what’s packed inside and what part is damaged.
Talking about splitting bone naturally brings to mind the orthopedic saw mentioned earlier. When dealing with a big bone like the sternum, which is like the trunk of a big tree, it’s much faster for the doctor to go straight in with an electric saw. Of course, the electric saw in the doctor’s hand is definitely not the same kind they use on construction sites outside—if you brought that thing up onto the operating table, you’d probably scare the patient to death before anything else.
An orthopedic saw can be made very compact, and the surgical electric saw is the same way—designed to look like a handheld drill. As long as the power is sufficient and the teeth are sharp, it does the job just as well. The size of the tool is chosen based on the size of the target: you’re just splitting a piece of bone, not felling a giant tree, so there’s no need to bring out oversized equipment.
When you use an electric saw to cut down a tree, you don’t just hack at it randomly; you aim for a neat cut so the trunk splits cleanly into two sections in an instant, making the aftermath much easier to deal with.
The surgical electric saw, named the Sternum Saw, has to be used with the same planning and intent when splitting the sternum. You cut along the midline, and the edges are neat. First, that’s for cosmetic reasons. Second, the bone you’ve cut has to be wired back together after the surgery; if the cut is straight, it’s easy to match the edges up and it heals better. Third—and most important—it allows standardized exposure of the field behind the sternum, which is crucial for the subsequent internal-organ procedures. If you cut it crooked, once you pull the wound open you’ll have to readjust the entire surgical field; the patient suffers and the doctors suffer.
This is where the key step lies: you have to hit the midline accurately.
The problem isn’t just whether you can feel and mark the midline of the sternum accurately through the skin before surgery; once you open up and cut through the skin, that preoperative line is definitely gone, and you need to re-establish the midline from scratch.
After opening up, the surgeon has to trace out the midline of the sternum step by step; this process of carefully feeling along is at the same time the preparatory work before splitting the sternum. To understand how tricky this is, you have to remember that a bone isn’t just a simple slab—it has skeletal muscles and all sorts of other structures attached to it. When "servicing" a bone, the surgeon has to use their hands and instruments to clean and peel these attachments off, just like brushing away dust and wires from a metal machine part before working on it. The sternum, as a major bone in the body, has many muscle groups attached to it.
The Chief Surgeon, wearing gloves, reaches in and feels around, identifies the ribs on both sides to locate the outer edges of the sternum, then picks two or three midpoint positions, and uses them to form a vertical midline. After that, the nurse hands over a curved clamp—a medium-sized curved hemostat that we usually just call a "medium curve."
This is where you see why cardiothoracic surgery and neurosurgery are called the two "special" branches of surgery. They don’t just deal with internal organs; they also have to work on hard structures like bone. Orthopedics doesn’t have to handle internal organs. Most other surgical specialties have very little to do with bone as a hard material at all.