Cfrgtkky

Do people actually use the word “kaputt” in conversation?

It is definitely the preferred word used by native speakers to say that something is broken in spoken language (both formal and informal). I think in 99% of all cases a native speaker would use the word "kaputt" to say that some thing is defect.

This is also true for informal written language (such as e-mail among friends). However, in formal written language (e.g. a letter to an insurance company) you would use other words.

In formal written language you would use "defekt" (which means: It does not work as expected) or you would say that something is "nicht in Ordnung" (which means: "not OK"). You would also tend to use expressions that describe more specifically how exactly something is "broken" - For example by writing that your car has problems with the engine instead of saying that your car is "broken".

mein Knie ist kaputt

For context, the injury is fixable but will likely require surgical repair.

It is as well used for health context. Although usually not in serious context:

Ich bin total kaputt. (To be exhausted)
Ich glaube mein Knie ist kaputt. (My knee hurts.)

I have already heard people saying that some parts of the body are "kaputt" really meaning that they are injured in a way that they cannot be healed any more.

However, normally you would use expressions that describe an injury more specifically when seriously speaking about health problems.

If the knee is not healthy due to a broken bone, for example, you'll say that the knee is "gebrochen". This word also translates to the word "broken" in English but it has another meaning:

• The word "kaputt" means "broken" with the meaning that something is not OK, does not work correctly etc...


• The word "gebrochen" (in this case) means that something (such as a bone) has broken into parts because of a strong force pressing/pushing against it


• When some chain, string, rope breaks because of pulling to strong, you'll use the word "gerissen"

Do people actually use the word "kaputt" in conversation, or would this be a strange thing to say?

Yes, it is frequently used. You can use the expression with all kinds of object, e.g. Auto, Notebook, Waschmaschine, Bilderrahmen.

For example, if I recently got a serious knee injury, would it be acceptable to say something like "mein Knie ist kaputt"? (For context, the injury is fixable but will likely require surgical repair).

dwds.de lists words that are often connected with kaputt (emphasis mine):

Aufzug Auspuff Bandscheibe Bremse Ehe Fahrrad Fahrstuhl Fensterscheibe Fernseher Gelenk Glühbirne Heizung Hüfte Klimaanlage Knie Knochen Kühlschrank Reifen Reißverschluß Rolltreppe Scheibe Spielzeug Straßenlaterne Type Waschmaschine Wirbelsäule Zahn lachen müde ziemlich

You can see that kaputt is regularly used to describe injuries.

There are also some idioms and common expressions with kaputt:

• kaputt sein (to be very tired)


• etwas kaputt machen (to damage/destroy something - in a wide sense: hope, mood, a business, someone's reputation,...)


• sich kaputt lachen (to shake with laughter)


• kaputte Ehe (a marriage that is close to falling apart)

Edit:
There is one particular usage case that is not German. Hitler kaput (Гитлер капут) is a common Russian expression (and a comedy movie from 2008), but I've never heard kaputt referring to a person in German (apart from being tired).

Where I come from "kaputt" is widely used in several ways:

"Bisch du kaputt?" - Are you crazy? (jokingly)

"Mein Auto ist kaputt" - My car doesn't function anymore

"Ich bin echt kaputt" - I'm really exhausted

"Mein Knie ist kaputt" - I can't use my knee well (jokingly)

In formal language it still can be used to say that something is defect/damaged but most of the times there are other words used, like "defekt/beschädigt".

As the other answers state, kaputt is a very common word in conversation. In some dialects or subcultures, other words may be more common, such as hinüber / hin, im Eimer, and so on. Another extremely common way to express "is broken" is using a more descriptive phrase, like:

Mein Computer funktioniert nicht mehr. My PC does not work anymore.

Meine Uhr ist stehen geblieben. My watch has stopped ticking.

Die Vase ist zerbrochen. The vase has shattered.

Using "kaputt" for a health issue would be less common. "Ich bin kaputt" just means I'm exhausted (either tired or just recovering from exertion). "Mein Knie ist kaputt" would mean I can't use the knee for a while, or forever. So it can only be used for body parts where the "use" of the part is relatively straightforward: Knees yes, but not something unspecific like the stomach or something "useless" like a toe.

To broadly describe an injury to any body part, you can use:

Mein Knie ist verletzt. My knee is injured

Mein Handgelenk macht Probleme. My wrist causes me trouble.

Meine Schulter schmerzt. My shoulder hurts.

Or reverse, even more German:

Ich habe eine Verletzung am Knie.

Ich habe Probleme mit meinem Handgelenk.

Ich habe Schmerzen an der Schulter.

to say i am "kaputt" regarding the first marathon, mentioned before, is correct and usual. To say my Knee is "kaputt" is not really correct usuage, cause it regards a bit to much to mechanical things broken, which ofcourse can be meant symbolistic.
Additionally it is a kind of picky, to use "kaputt" in engineering-like areas, but usual, if you are in surroundings of ironical speech.