En skade i knæet kan få mig til at gå langsomt i flere dage.

Because skade is a common-gender noun in Danish. Common-gender nouns take en in the singular indefinite form.

• en skade = an injury
• skaden = the injury

So this part simply means an injury.

Knæ is a neuter noun, so its forms are:

• et knæ = a knee
• knæet = the knee

In the sentence, Danish uses the definite form knæet, so it means the knee.

Here, i knæet means something like in the knee or in the knee joint/area. It suggests that the injury affects the knee internally or as a body part, not just the surface.

This is very natural in Danish when talking about pain, injuries, or physical problems in body parts.

Because i and på suggest different things.

• i knæet = in the knee, affecting the knee itself
• på knæet = on the knee, often more like on the surface of the knee

So if you scraped the skin on your knee, på knæet might make sense. But for an injury inside or involving the knee as a joint, i knæet is more natural.

Danish often uses the definite form of the body part instead of a possessive like my, especially when it is already obvious whose body part it is.

So:

• en skade i knæet = an injury in the knee
• English often prefers my knee in similar contexts, but Danish does not always need that

You could say i mit knæ if you want to emphasize that it is my knee, but it is not necessary here.

This is a very common Danish structure:

få nogen til at + infinitive

It means:

• make someone do something
• cause someone to do something
• sometimes get someone to do something

So:

• kan få mig til at gå langsomt = can make me walk slowly

Here få does not mean receive/get in the simple English sense. It is part of a causative expression.

Because mig is the object form of the pronoun.

• jeg = I
• mig = me

In this sentence, the injury is the thing doing the causing, and me is the person affected:

• En skade i knæet kan få mig... = An injury in the knee can make me...

Just like in English, you say make me, not make I.

Because the pattern is:

få + object + til at + infinitive

So:

• få mig til at gå = make me walk

The at is part of this infinitive construction. After til, Danish often uses at + verb in this specific pattern.

Because langsomt is the adverb form, and it describes how you walk.

• langsom = slow, used for a noun
• langsomt = slowly, used for a verb

So:

• en langsom person = a slow person
• gå langsomt = walk slowly

A lot of Danish adjectives form the adverb by adding -t.

I flere dage means for several days.

In Danish, i + time period is often used to express duration:

• i flere dage = for several days
• i to timer = for two hours

So the i here does not mean physical location. It marks how long something lasts.

The sentence is built like this:

• En skade i knæet = subject
• kan = finite/modal verb
• få mig til at gå = verb chain
• langsomt = adverb
• i flere dage = time expression

So the sentence follows normal Danish main-clause word order, where the finite verb comes early in the sentence.

A rough breakdown is:

En skade i knæet
kan
få mig til at gå
langsomt
i flere dage

This is very typical Danish structure.

Yes. En knæskade means a knee injury, and it is often a very natural alternative.

So these are both possible:

• En skade i knæet
• En knæskade

The first one emphasizes an injury in the knee. The second packages it as a compound noun, which Danish does very often. Both are understandable and natural, though knæskade may sound a bit more compact and idiomatic in many contexts.