Modified Lateral Gastrocnemius Myocutaneous Flap With Extended Anterior And/or Inferior Boundary:Anatomic Study And Clinical Application

Objective:The purpose of this study is to explore the arterial anatomy basis of modified lateral gastrocnemius myocutaneous flap with extended anterior or inferior boundary or both; Arc of rotation of modified lateral gastrocnemius muscle (myocutaneous) flap was quantitatively measured on specimen. And we describe clinical experience of the modified lateral gastrocnemius myocutaneous flap.Methods:Twelve fresh lower extremity from amputation above knee because of bone tumor were included in this study. Five cases were injected with latex barium sulfate solution through femoral artery, and the origin, distribution, quantity and diameter of the skin perforators in the lower leg were dissected and recorded; then, the integument covering the lower leg was examined under X-ray. One case was perfused with methylene blue and was observed. Six cases were observed that the distal of lateral gastrocnemius muscle (myocutaneous) flap could arrived in the segments of leg, and the arc of rotation was quantitatively measured. There were25modified lateral gastrocnemius myocutaneous flaps with extended anterior and/or inferior boundary utilized in clinic, including16flaps with extended anterior boundary,2flaps with extended inferior boundary, and7flaps with extended both anterior and inferior boundary. In23flaps with extended anterior boundary, the distance between the anterior boundary and the anterior crista of the fibula ranged from1.5cm to7.5cm (averagely,3.9cm). Among9flaps with extended inferior boundary, the inferior boundary was located at3cm above the lateral malleolus in2cases, at5cm above the lateral malleolus in4cases, and at7cm above the lateral malleolus in3cases. In3patients, the defects were involved in the distal one-third of the leg.Results:The lateral popliteal cutaneous artery arised from the popliteal artery averagely1.3cm above the popliteal crease, then ran outward and down. The inferior lateral genicular artery issued three perforators0-1cm above the fibular head, one overlying the lateral compartment and two overlying the anterior compartment. One perforator from the circumflex fibular artery pierced the deep fascia over the lateral compartment3.4cm below the fibular head. The arteriograph showed the features as follows. The inferior lateral genicular artery anastomosed with the lateral popliteal cutaneous artery, perforators from both the upper anterior tibial artery and the circumflex fibular artery, and arterial network around the superficial sural nerve; Both the lateral popliteal cutaneous artery and musculocutaneous perforators from the lateral sural artery had rich linked arteries communicating with chain-linked arterial network around both the posterolateral intermuscular septum and the sural nerve, and they also had rich transverse communicating arteries connecting with the suprafascial arterial network overlying the anterior compartment in the upper and middle calf; Continueous fascial arterial networks beginning with the inferior lateral genicular artery over the anterior compartment, and both the lateral popliteal cutaneous artery and musculocutaneous perforators from the lateral sural artery over posterolateral calf extended up to the level at the intermalleolus line. The distal end of the modified flap with inferior border3cm above the lateral malleolus reached the17th area (the ninth zone) laterally and the16th area (the eighth zone) medially, and an average of5.5cm above the intermalleolus line. Twenty-two flaps survived, part necrosis occurred in two flaps with inferior border5cm and3cm above the lateral malleolus, respectively, and one flap with inferior border5cm above the lateral malleolus developed marginal necrosis.Conclusions:(1) Multiple feeder arteries, including the lateral sural artery, lateral popliteal cutaneous artery, and inferior lateral genicular artery, are the arterial anatomic basis of the modified lateral gastrocnemius myocutaneous flap with extended anterior and/or inferior boundary.(2) The modified lateral gastrocnemius myocutaneous flap with extended inferior boundary can repair some pretibial soft tissue defects in the lower third of the leg, and quantitative measures of the rotation arc of the lateral gastrocnemius muscle (myocutaneous) flaps provide a valuable reference for the clinical application.(3) The modified lateral gastrocnemius myocutaneous flap with extended anterior and/or inferior boundary is feasible, and the modified flaps with extended anterior boundary is safe and reliable.