2. Traction with a limb positioner

To insert a pin for traction, the knee was flexed to 30◦ with neutral rotation. Using a pointed scalpel, a stab incision was made through the skin on the medial side 2–3 finger breadths above the superior pole of the patella. After placing a 3.2 mm Steinmann pin on the drill, insertion was made parallel to the joint line from the medial to lateral sides. Further, after driving the Steinmann pin through the bone and ensuring that the pin had penetrated the far cortex, another stab incision was made on the overlying skin, coinciding with the expected exit of the pin. After the Steinmann pin was completely out, the tension on the skin at the entry and exit points was checked. A small relieving incision was additionally performed in case of excessive tension.

The Steinmann pin was transfixed and then connected with a traction stirrup and affixed to the limb positioner (The Spider Limb Positioner, Smith and Nephew®, Andover, MA, USA). Sterility was assured by first covering the limb positioner with the manufacturer's sterile drape and then proceeding with standard sterile pelvic draping (Figure 2). Subsequently, sufficient manual traction force was applied through the stirrup, and the degree of reduction was confirmed using an image intensifier (Figure 3). The stirrup was then connected to the pneumatic limb positioner and locked while maintaining traction (Figure 2D and Video S1).

**Figure 2.** After transfixing the Steinmann pin in the distal femur, it was connected with a traction stirrup (**A**). The Stein-mann pin-traction stirrup construct was affixed to the limb positioner (**B**). Sufficient manual traction force was applied through the stirrup (**C**). The limb positioner was locked while maintaining traction (**D**).

**Figure 3.** Intraoperative image before (**A**) and after (**B**) traction.
