The Patella and Patellar Retinacula The medial and lateral patellar retinaculaare then palpated. In typical lateral patellar dislocations, the medial retinaculum is torn and painful to the touch. Complete medial avulsions occationally occur, and a defect will be palpable where the retinaculum and vastus medialis have pulled away from the patella.The pain and swelling on direct palpation over the patella can indicate a patellar fracture or injury or inflammation of the prepatellar bursa. The completion of the patellar portion to the exam is the examiner palpates the infrapatellar tendon. The active knee extension assesses the integrity of the patellar attachments and the knee should always be elevated when it is an acute knee injury. A loss of knee extension against gravity may rupture in the patellar tendon or quadricepts femoris tendon. The full extension is difficult and discomfortable and the patient would have a partial rupture, with retinacular fibers remaining intact.