Старый шрам на колене снова стал заметнее после того, как я упал на лестнице.

Шрам is in the nominative singular because it is the subject of the sentence—the thing that became more noticeable.

Старый is also nominative singular, masculine, because it agrees with шрам:

• старый = masculine singular nominative
• шрам = masculine singular nominative

So старый шрам is a normal adjective + noun combination meaning old scar.

After на, Russian can use different cases depending on meaning:

• на + accusative = motion onto something
• на + prepositional = location on something

Here the meaning is on the knee, so Russian uses the prepositional case:

• колено → на колене

Also, the noun колено has the prepositional singular form колене. So:

• шрам на колене = a scar on the knee

It usually means old in the sense that the scar has been there for a long time. With things like scars, wounds, injuries, etc., старый often means not recent or long-standing, not literally ancient.

So старый шрам is a very natural phrase for an old scar.

Заметнее is the comparative form of заметный.

• заметный = noticeable, visible
• заметнее = more noticeable, more visible

Russian often forms comparatives with -ее / -ей:

• тихий → тише
• быстрый → быстрее
• заметный → заметнее

So стал заметнее means became more noticeable.

Because стал shows a change of state.

• был заметнее = was more noticeable
• стал заметнее = became more noticeable

The sentence is describing that the scar changed after the fall, so стал is the natural choice.

This pattern is very common in Russian:

• стало лучше = it got better
• стал сильнее = became stronger
• стала красивее = became prettier

Снова means again. In many sentences, снова and опять are interchangeable.

However, there is a slight tendency:

• снова often sounds a bit more neutral
• опять can sometimes sound more emotional, especially again!

Here снова fits well because the sentence is just stating a fact:

• снова стал заметнее = became more noticeable again

После того, как is a very common way to say after before a full clause.

It introduces a subordinate clause:

• после того, как я упал на лестнице = after I fell on the stairs

This expression is built like this:

• после = after
• того = that
• как = how/as/that in this structure

In practice, you should learn после того, как as a set expression meaning after.

The comma before как is standard in this kind of structure.

Because упал is perfective, and it describes one completed event: the person fell.

• упал = fell, had a fall
• падал = was falling / used to fall / fell repeatedly, depending on context

Here the sentence refers to one specific incident, so упал is the natural choice.

Also, упал is the masculine past tense form. If the speaker were female, it would be:

• я упала

These mean different things:

• на лестнице = on the stairs / on the staircase
• с лестницы = from the stairs / off the stairs / down the stairs

So:

• я упал на лестнице = I fell while I was on the stairs
• я упал с лестницы = I fell off/down the stairs

The sentence uses на лестнице because it focuses on where the fall happened, not necessarily the direction of the fall.

Also, note that Russian often uses singular лестница where English often uses plural stairs.

Yes. Russian word order is flexible, and different orders can change emphasis.

The given order is natural and neutral:

• Старый шрам на колене снова стал заметнее после того, как я упал на лестнице.

But Russian could also say, for example:

• После того, как я упал на лестнице, старый шрам на колене снова стал заметнее.

That version emphasizes the time/event first: After I fell on the stairs...

So the original sentence is not the only possible order, but it is very normal.

This is a good question because Russian comparatives can look the same in both uses.

Here заметнее functions as part of the predicate after стал, so it is best understood as comparative predicate meaning more noticeable.

In practical terms, for a learner, the important pattern is:

• стать + comparative = become more ...

For example:

• стал лучше = became better
• стала тише = became quieter
• стало труднее = became harder

So even if the exact label feels tricky, the structure itself is very common and worth memorizing.