He sprained/tore 'ligaments' in his knee.
(..) Well, that's one way to pull a tooth. Darn kids. Well, good thing l pulled the right one, eh? Nigel, you just missed an extraction. Has he loosened the periodontal ligament yet? What am l talking about? Where's Nemo? l've got to speak with him. Your dad's been fighting the ocean looking for you. (..)2003 Finding Nemo