Ruptures of the anterior cruciate ligament are among the most frequent sport injuries of the younger population. The reconstruction of the anterior cruciate ligament is often indicated to stabilize the knee in younger patients with a good compliance. The use of the mid third of the patellar ligament with a bone block out of the patella and the tibial tuberosity as a ligament graft is a well recognized method. A disadvantage of the above mentioned technique is the so called donor site pathology , a pain syndrome mainly around the tibial tuberosity after graft harvesting. Often adhesions of the distal third of the patellar ligament with the tibia are the reasons for this pain syndrome. The adhesions are detectable by clinical examination as well as on lateral X-rays. The therapy consists of a short outpatient surgical intervention. The adhesions are opened by means of a Kelly-clamp. It is the goal of this paper to present the diagnostics and therapy of the adherent patellar ligament after it has been used as a ligament graft source.