Μετά την πτώση, είχα πόνο στο γόνατο και στην πλάτη.

In Modern Greek, μετά meaning after is followed by the accusative case.

So:

• η πτώση = the fall nominative
• την πτώση = the fall accusative

That is why the sentence has μετά την πτώση.

A useful contrast:

• μετά
  • accusative = after
• older/literary μετά
  • genitive can mean with, but that is not normal everyday Modern Greek usage in a sentence like this.

Because many feminine nouns in -ση have the same form in the nominative and accusative singular.

So:

• η πτώση = nominative
• την πτώση = accusative

The noun itself does not change here, but the article changes and shows the case.

This is very common:

• η στάση / τη στάση
• η λύση / τη λύση
• η πτώση / την πτώση

Είχα is the imperfect of έχω.

• έχω = I have
• είχα = I had / I was having

Since the sentence talks about a past situation, Greek uses είχα.

In this sentence, είχα πόνο... means something like:

• I had pain...
• I was in pain...

The imperfect is very natural here because it describes a past state rather than a single completed action.

Because πόνο is the accusative singular, and here it is the direct object of είχα.

• ο πόνος = pain, nominative
• τον πόνο = pain, accusative
• without the article: πόνο

So:

• είχα πόνο = I had pain

This is the same pattern as:

• έχω χρόνο = I have time
• είχα φόβο = I had fear
• είχα πόνο = I had pain

Greek often leaves out the article with nouns like pain, fear, hunger, headache, etc., when speaking in a general or indefinite way.

So είχα πόνο means I had pain or I was in pain.

If you used the article, είχα τον πόνο, it would usually sound more specific or marked, and it would not be the normal phrasing here.

This article-less use is very natural in Greek.

They are contractions of σε + the definite article.

• στο = σε + το
• στην = σε + την

Here they mean in, at, or on, depending on the context.

So:

• στο γόνατο = in/on the knee
• στην πλάτη = in the back / in the back area

Greek uses σε very widely where English might choose in, on, or at.

Because the nouns have different genders.

• το γόνατο = the knee neuter
• η πλάτη = the back feminine

Since στο comes from σε + το, it is used with neuter singular nouns:

• στο γόνατο

And στην comes from σε + την, so it is used with feminine singular nouns:

• στην πλάτη

So the difference is grammatical gender, not a difference in meaning.

Greek often omits the possessive with body parts when it is obvious whose body is being talked about.

So:

• είχα πόνο στο γόνατο very naturally means I had pain in my knee
• είχα πόνο στην πλάτη very naturally means I had pain in my back

Adding μου is possible:

• στο γόνατό μου
• στην πλάτη μου

But it is often unnecessary unless you want to emphasize it or make it especially explicit.

This is very common in Greek and can feel more natural than always using my as in English.

Because one noun, πόνο, can apply to both body parts.

So the structure is basically:

• I had pain
• in the knee
• and in the back

Greek does not need to repeat πόνο:

• είχα πόνο στο γόνατο και στην πλάτη

This is just like English:

• I had pain in my knee and back

You could repeat it, but it would usually be less natural unless you wanted emphasis.

Yes, Greek word order is quite flexible.

The sentence begins with Μετά την πτώση to set the time/context first:

• After the fall, I had pain...

That is very natural.

But Greek could also say:

• Είχα πόνο στο γόνατο και στην πλάτη μετά την πτώση.

That would still be correct. The version with Μετά την πτώση first gives a slightly clearer setup and sounds very natural in narration.

The comma separates the introductory time phrase from the main clause.

So:

• Μετά την πτώση, = introductory phrase
• είχα πόνο στο γόνατο και στην πλάτη. = main statement

This is similar to English punctuation in:

• After the fall, I had pain in my knee and back.

In short sentences, Greek punctuation can sometimes be flexible, but the comma here is completely normal and helpful.

Here it means in the back in the sense of back pain.

Greek uses σε very broadly, so you should not try to match it mechanically to one English preposition.

• πόνο στην πλάτη = pain in the back / back pain

English and Greek divide these meanings a bit differently, but this Greek phrase is very standard.

Yes. Η πτώση is a standard noun meaning fall.

So:

• πέφτω = I fall
• η πτώση = the fall

In a medical or accident-related context, μετά την πτώση is very natural and common, especially in written or formal speech.

In more casual speech, Greeks might also describe the event in other ways, but this wording is perfectly normal and clear.