Mark the midline of the skin before incising, ensuring that the skin incision is in the midline. Extend it from the sternal notch to a point roughly 1 to 2 cm below the tip of the xiphoid. Using electrocautery, divide the connective tissue until the sternum is reached. Occasionally, there is a thin layer of decussating pectoral muscle in the midline over the sternum. Divide this and score the external periosteum of the sternum with electrocautery. Carefully palpate the lateral edges of the sternum with the thumb and index finger of your nondominant hand so that the incision can be kept directly in the midline. At the angle of Louis (sternomanubrial junction), use a snap or forceps to identify the lateral margins of the sternum. This is advised because the pectoralis muscles do not universally delineate the center of the sternum. Straying off the midline will later cause the sternal retractor to “kick up” on the thinner side and can adversely affect healing of the sternal bone.

Score the periosteum caudally to the tip of the xiphoid. Divide the abdominal fascia in the midline for a short distance, taking care not to enter the peritoneum. Superiorly, score the periosteum to the sternal notch and carefully feel for a tough ligamentous structure on the posterior aspect of the notch. Divide this ligament with great care using cautery. (The electric sternal saw frequently will jam or bog down on tissue of this type.) Introduce your index fingers under the sternum from both the sternal notch and the xiphoid. Gentle dissection here will facilitate detachment of the underlying structures from the back of the sternum before the sternum is divided. Ask the anesthesiologist to deflate the lungs fully to allow the pleura to fall posteriorly as much as possible. Bisect the sternum with the sternal saw starting from either end. Pull gently up and forward with the saw during this maneuver, again to reduce the risk for injury to underlying structures. Obtain hemostasis by cauterizing the periosteum along the lower edge of the sternum. Because the soft tissue will slightly retract after sternal division, be sure to cauterize several millimeters back along the undersurface of the cut sternum. The divided edge of the sternum often oozes from the marrow. Application of a paste containing thrombin, Gelfoam, or a similar material will promote hemostasis and keep your field clean.

Place folded green towels along the divided edges of the sternum and insert the sternal retractor. When you place the sternal spreader, remember that the more cephalad the retractor is placed, the greater the risk for injury to the brachial plexus.
In the situation of a tight or limited exposure, modest additional division of the midline abdominal fascia (extraperitoneal) may be beneficial.