The acute ligament rupture in the ankle joint still falls within the domain of conservative therapy. Therapy recommendations diverge strongly, and no standardized protocol exists. Chronic ligament instability primarily resulting from acute ligament ruptures occurs with an incidence of 20% to 60% depending on the study. The treatment for chronic instability involves various techniques. Direct ligament repair has not resulted in highly successful outcomes. The prevalent reason for this is the weak caliber of the lateral ligaments, both the anterior talofibular ligament and the calcaneofibular ligament, both of which seem to be inadequate for a direct suture repair because of their structure. In the past, tenodesis-type stabilization techniques (Anderson, Hintermann) were widely used. In contrast, anatomic reconstructions using local structures are in widespread use today and are less invasive. The most common technique used today is the modified Broström method. Here, we present a surgical method using the retinaculum extensorum inferius for stabilization similar to the Broström method. Arthroscopy of the ankle joint is performed before stabilization, for diagnostic purposes and to treat accompanying pathologies within the ankle.