sich den Arm brechen

German uses a reflexive structure here. You need the reflexive pronoun in the dative case. For example, ich mir, du dir, or er sich. You also use the definite article den instead of the possessive 'my'. So, you say Ich habe mir den Arm gebrochen. It sounds like 'I broke to me the arm.' This is a very common pattern for body parts in German. Always remember to match the pronoun to the person who got hurt. If your friend fell, you say Du hast dir den Arm gebrochen.

Use this when talking to a doctor or an insurance agent. It is perfect for telling friends why you can't go climbing. You might use it in a text message to explain a sudden absence. It fits well in any conversation about health or accidents. If you see someone in a cast, this is the phrase you need. It is useful at work to explain why you are typing slowly. Even children use this phrase on the playground.

Do not use this for minor injuries like a bruise. It is strictly for a broken bone. Also, don't confuse it with the English 'break a leg' for good luck. In German, that is Hals- und Beinbruch. If you say Ich breche mir den Arm for luck, people will be very confused. They might even try to call an ambulance for you! Avoid using it metaphorically to mean something is difficult. Stick to the physical reality of the injury.

Germans are generally very direct about health issues. Discussing injuries isn't seen as oversharing in most contexts. There is a strong culture of outdoor activities like hiking and skiing. Consequently, breaking a limb is a common topic of conversation. Health insurance and 'Krankenschein' (sick notes) are huge parts of German life. Knowing how to name your injury is practically a survival skill. It shows you can navigate the very organized German medical system.

You can swap Arm for any other body part. Sich das Bein brechen means breaking a leg. Sich den Finger brechen is for a finger. If you want to sound more medical, you could use Fraktur. However, brechen is much more common in daily life. You can also add adverbs like kompliziert for a complex break. Most people just stick to the simple version. It gets the point across quickly and clearly.