Кістка зламалася.

Зламалася is the past tense of зламатися, which means to break in the sense of to become broken.

The ending -ся makes the verb reflexive, but in Ukrainian reflexive verbs are not only used for actions someone does to themselves. Very often, -ся also gives the idea that something happens to the subject.

So:

• ламати = to break something
• зламати = to break something completely / successfully
• зламатися = to break, to get broken

In this sentence, the bone is not breaking something else. The bone itself becomes broken, so зламалася is the natural form.

Кістка is in the nominative singular, because it is the subject of the sentence.

In Кістка зламалася, the bone is the thing that underwent the action, so nominative is used:

• кістка = bone as the subject
• кістку = accusative singular, often used as a direct object
• кістки = could be genitive singular or nominative plural, depending on context

So here, кістка is the correct form because the sentence is basically The bone broke.

The verb is feminine because кістка is a feminine noun.

In the past tense, Ukrainian verbs agree with the subject in gender and number:

• masculine: зламався
• feminine: зламалася
• neuter: зламалося
• plural: зламалися

Since кістка is feminine singular, the correct form is зламалася.

Зламалася is perfective.

The perfective verb here is зламатися, which focuses on the result: the bone ended up broken.

Compare:

• ламалася = imperfective, was breaking, kept breaking, or used to break, depending on context
• зламалася = perfective, broke / has broken, with emphasis on the completed event

So Кістка зламалася presents the break as a completed event.

You usually would not use Кістка ламалася for a simple statement that the bone broke.

Ламалася is imperfective, so it sounds more like:

• the bone was in the process of breaking
• the bone kept breaking
• the bone tended to break

That is usually not what you want for a straightforward event.

For a normal statement like The bone broke, Кістка зламалася is much more natural.

The difference is in who is presented as the doer of the action.

• Кістка зламалася = The bone broke

  • the bone is the subject
  • no external agent is mentioned
  • it sounds intransitive

• Хтось зламав кістку = Someone broke the bone

  • хтось is the subject
  • кістку is the direct object
  • it is clearly transitive

So the sentence you were given focuses on the result affecting the bone, not on who caused it.

Yes. Ukrainian has no articles like a and the, so Кістка зламалася could mean either:

• The bone broke
• A bone broke

The exact meaning depends on context.

For example:

• if you are already talking about one specific bone, it will likely mean the bone
• if you are introducing new information, it may feel more like a bone

A rough pronunciation guide is:

KEES-tka zla-MA-la-sya

A few details:

• і sounds like ee in see
• зл at the start of зламалася can feel a little tricky for English speakers, because Ukrainian allows consonant clusters more freely
• ся is pronounced approximately like sya

If you want a more careful breakdown:

• Кістка = KEES-tka
• зламалася = zla-MA-la-sya

The stress is usually:

• Кі́стка
• злама́лася

Because Ukrainian does not need a separate verb like was here.

In the past tense, the main verb itself carries the meaning. So зламалася already means broke or was broken in the right context.

Ukrainian often expresses ideas more compactly than English in this way.

Yes, in some contexts that is a useful way to understand it.

Because зламатися means something like to become broken, Кістка зламалася can sometimes feel close to:

• The bone broke
• The bone got broken

But in normal English, The bone broke is usually the most natural translation unless the context specifically emphasizes the change of state.

The plural would be:

Кістки зламалися.

That means The bones broke or Some bones broke, depending on context.

Notice the changes:

• кістка → кістки for plural
• зламалася → зламалися because the subject is now plural

Yes, Кістка зламалася is natural Ukrainian.

However, in real-life situations people may also say more specific things, for example:

• Я зламав кістку. = I broke a bone.
• У нього зламалася кістка. = He has broken a bone / A bone of his broke.
• У неї перелом. = She has a fracture.

So your sentence is correct and natural, but everyday speech may often use a more specific or more idiomatic phrasing depending on the situation.