Si me hubiera dolido más la rodilla, habríamos tenido que volver a la consulta.

This is a past unreal conditional structure, often called the third conditional.

It talks about a situation that did not actually happen in the past, and its imagined result.

The pattern is:

• Si + pluperfect subjunctive
• conditional perfect

So here:

• si me hubiera dolido más la rodilla = if my knee had hurt more
• habríamos tenido que volver = we would have had to go back

This structure is used for hypothetical past situations:

• Si hubiera estudiado más, habría aprobado. = If I had studied more, I would have passed.

Because after si in this kind of hypothetical sentence, Spanish uses the subjunctive, not the conditional.

So:

• Correct: Si me hubiera dolido...
• Incorrect: Si me habría dolido...

A very common rule is:

• si
  • subjunctive
• main clause + conditional

Compare:

• Si tuviera tiempo, iría.
• Si hubiera tenido tiempo, habría ido.

English learners often want to put would have in both parts, but Spanish does not do that.

Hubiera dolido is the pluperfect subjunctive (also called the past perfect subjunctive).

It is formed with:

• hubiera / hubiese
• past participle

So here:

• hubiera
  • dolido

This tense refers to something hypothetical or unreal before another past point.

Examples:

• Si hubiera venido, lo habríamos visto.
• Si me hubiera llamado, habría contestado.

In your sentence, it means the knee did not in fact hurt more, but we are imagining what would have happened if it had.

Yes. Hubiera and hubiese are both correct here.

So these mean the same thing:

• Si me hubiera dolido más la rodilla...
• Si me hubiese dolido más la rodilla...

In modern Spanish, hubiera is usually more common in everyday use, but both are standard.

Because doler works like gustar in its grammar.

In Spanish, you do not usually say something like I hurt my knee if you mean the knee was painful. Instead, the body part is the thing that causes pain, and the person experiencing it is shown with an indirect object pronoun.

So:

• Me duele la rodilla = My knee hurts / My knee is hurting
• literally: The knee hurts to me

In your sentence:

• me hubiera dolido la rodilla = my knee had hurt

The me shows who felt the pain.

Other examples:

• Me duele la cabeza.
• Le dolían los brazos.

With body parts, Spanish often uses the definite article (el, la, los, las) instead of a possessive adjective (mi, tu, su) when the owner is already clear.

Since me already tells us whose knee it is, Spanish normally says:

• me duele la rodilla not usually
• me duele mi rodilla

So in your sentence:

• me hubiera dolido más la rodilla = if my knee had hurt more

This is very natural Spanish.

The same pattern appears with other body parts:

• Me lavé las manos.
• Le duele la espalda.
• Nos rompimos el brazo.

Because with verbs like doler, Spanish often places the indirect object pronoun first and the thing causing the feeling after the verb.

So this is very natural:

• Me duele la rodilla
• Me hubiera dolido más la rodilla

But you can also say:

• Si la rodilla me hubiera dolido más...

That version is grammatically possible, but it may sound slightly more marked or focused on the knee itself.

The usual, neutral order is the one in your sentence.

Más means more, and here it modifies the idea of how much it hurt.

So:

• me hubiera dolido más la rodilla = my knee had hurt more

It is about the degree of pain, not the length of time.

Compare:

• Me dolió más hoy que ayer. = It hurt more today than yesterday.
• Me dolió mucho. = It hurt a lot.

Habríamos tenido que volver is the conditional perfect of tener que + infinitive.

It means:

• we would have had to return / go back

Breakdown:

• habríamos tenido = we would have had
• que volver = to return / to go back

So the whole idea is:

• we would have had to go back

This fits the unreal past condition established in the first clause.

Tener que + infinitive expresses necessity or obligation.

So:

• tener que volver = to have to go back

In this sentence, it means that if the knee pain had been worse, going back would have been necessary.

Spanish could sometimes use deber in similar contexts, but tener que is very common and very natural for a practical necessity.

Volver means to return, to go back, or to come back, depending on context.

So:

• volver a la consulta = to go back to the doctor’s office / clinic / consulting room

In Spain, la consulta often refers to:

• a doctor’s consulting room
• a medical appointment setting
• the practice/office where the doctor sees patients

So this does not mean to consult again in the English sense. Here it means physically returning to the medical place.

Because the subject of the main clause is we, not I.

The sentence says:

• habríamos tenido que volver = we would have had to go back

Even though only one person’s knee is hurting, the result affects a group of people, so the verb is plural.

A common real-life context would be:

• one person is at the doctor with someone else
• if the pain had been worse, both of them would have had to go back

Yes, but it means something different.

• Si me hubiera dolido más la rodilla, habríamos tenido que volver... = past unreal situation
  = If my knee had hurt more, we would have had to go back.

• Si me doliera más la rodilla, tendríamos que volver... = present/future hypothetical situation
  = If my knee hurt more, we would have to go back.

So the original sentence is about a past event that didn’t happen.
Your alternative would be about a current or possible situation.

Very often, yes.

The thing that hurts is treated as the grammatical subject, and the person affected is shown with an indirect object pronoun:

• Me duele la espalda.
• Le dolían los pies.
• Nos ha dolido mucho la cabeza.

That is why the sentence is not built like:

• yo hubiera dolido la rodilla

That would be wrong.

Instead, Spanish says:

• me hubiera dolido la rodilla

Normally, no. In the main clause of this type of sentence, Spanish usually uses the conditional perfect:

• habríamos tenido que volver

Using the pluperfect subjunctive in both clauses can happen in some regional or literary usage, but for standard learning purposes, the normal and recommended pattern is:

• Si + hubiera/hubiese + participle
• habría/habrías/habríamos... + participle

So the best standard version is the one in your sentence.

Yes, it sounds natural.

It uses very standard features of Spanish from Spain:

• normal body-part structure: me ... la rodilla
• a common unreal past conditional
• natural medical vocabulary: la consulta
• natural result phrase: habríamos tenido que volver

A speaker in Spain would easily understand it and would likely say something very similar in the right context.