Learn Spanish (Latin America): Me duelen el codo y la rodilla.

Just like gustar, the verb doler (to hurt) matches the things causing the feeling. Even though el codo (the elbow) and la rodilla (the knee) are singular on their own, together they make a plural subject (elbow and knee). Since two things are hurting you, we use the plural form duelen.

The translation says 'my elbow', but the Spanish uses el (the). Why not use mi codo?

In Spanish, we use definite articles (el, la, los, las) instead of possessive words (like mi or mis) when talking about our own body parts. The listener already knows whose elbow and knee are hurting because of the me (to me) at the beginning of the sentence.

How exactly does the word order work here with Me duelen?

Doler works just like gustar. Instead of saying 'I hurt my elbow', the Spanish phrasing is closer to 'The elbow and the knee cause pain to me.' The me tells us who is receiving the pain, and it comes right before the verb.

The dictionary form is doler, so why is it spelled with a 'ue' in duelen?