Microscopic Anatomical Study of the Choke Zone in Valgus Knee Arthroplasty Incisions and its Clinical Implications

To investigate the anatomical characteristics of the lateral skin region in valgus knee arthroplasty incisions, specifically the size and distribution of the lateral perforator Choke zone, in order to guide incision placement during knee arthroplasty and reduce the risk of compromised skin perfusion.

From October 2019 to September 2024, 70 patients undergoing valgus knee arthroplasty with iliotibial band (ITB) release were followed to record the incidence of lateral skin perfusion impairment, including a detailed report of a typical case of lateral skin necrosis. Additionally, from October to November 2024, 10 knees from 5 adult cadavers were perfused via the femoral artery using red latex-lead oxide. The lateral superior genicular artery (LSGA) perforators, Choke zone, and surrounding skin and soft tissue perfusion were anatomically dissected, observed, and measured.

Postoperatively, 10 patients (14.3%) showed lateral knee skin swelling with perfusion impairment. The distance from the center of the perfusion-compromised area to the joint line was 1.9 ± 0.6 cm, and the area of perfusion deficit was 15.0 ± 6.6 cm²; all cases healed with conservative treatment. One patient developed lateral skin necrosis, which was successfully treated with debridement and flap reconstruction. Cadaveric dissection revealed an average of 2.20 ± 0.75 LSGA perforators per knee. The origin of the perforators was 4.61 ± 1.16 cm from the joint line, with a diameter of 2.06 ± 0.35 mm, and the exit point located 4.24 ± 1.36 cm from the joint line. The perforator length averaged 7.36 ± 2.42 cm. Distal skin perfusion extended 2.45 ± 1.78 cm beyond the joint line, while proximal perfusion reached 13.56 ± 4.72 cm. The center of the Choke zone was 2.00 ± 1.12 cm from the joint line, with an area of 10.00 ± 3.51 cm².

The blood supply of the superior lateral genicular artery branches generally extends only about 2 cm up to the joint line. The Choke area formed with the inferior lateral genicular artery is small and poorly perfused, making it prone to intraoperative injury and localized ischemia. Therefore, iliotibial band release and lateral incisions should avoid the joint line and Choke area to minimize the risk of postoperative skin ischemia and necrosis.