Extensor apparatus injuries have an incidence of 0.5–6 %. Patellar tendon is part of this structure, and its rupture is the third in frequency after patella and quadriceps tendon ones. However, despite the rarity of this lesion, it is a dramatic injury with important consequences on knee function. Patellar tendon rupture can be divided into acute or chronic. Both acute and chronic lesions are usually consequent to tendon degeneration for microtraumas or systemic pathologies. Different surgical techniques have been described, and it has to be differentiated for acute or chronic lesions, but in literature, there is no consensus on the treatment indication. On acute lesion, primary repair is the best choice, but there is still a debate on literature if an augmentation is needed or not. In chronic lesion, primary repair is often not possible because of tendon retraction, so a reconstruction using autograft or allograft is usually performed. In this chapter, we will treat etiology and diagnosis of patellar tendon rupture, including the most common procedures with their indications and results.