What To Do After a Suspected ACL Tear

If you’re reading this, there’s a good chance something didn’t feel right in your knee.

Maybe you felt a pop.
Maybe your knee gave way.
Maybe it swelled up within a few hours.

And now you’re sat there thinking:

“Have I torn my ACL?”

You might even have already sat and read my article on ACL tear symptoms.

First of all — breathe.

As someone who tore my own ACL and now works with ACL patients every week in clinic, I can tell you this:

What you do in the first few days and weeks matters.

So here’s exactly what to do after a suspected ACL tear.

Step 1: Recognise the Common ACL Tear Symptoms

Not every ACL injury feels dramatic. But there are classic signs.

The most common ACL tear symptoms are:

• A popping sensation at the time of injury

• Rapid swelling within 1–3 hours

• Pain deep inside the knee

• Instability or the feeling your knee might “give way”

• Difficulty fully straightening the knee

If your swelling came on quickly, that’s significant. Rapid swelling usually means bleeding inside the joint — and the ACL has a strong blood supply.

That said: not all ACL injuries swell massively. And not all painful knees are ACL tears.

Which is why the next step is critical.

Step 2: Don’t Self-Diagnose — Get Assessed

Google cannot diagnose your knee.

Even experienced clinicians don’t rely purely on symptoms — we use specific ligament tests to assess stability.

If you suspect an ACL tear:

• Book an assessment with a sports therapist, physio or knee specialist

• If you’re in the UK, speak to your GP for referral if needed

• If instability is severe or you cannot weight-bear, attend A&E

An MRI scan is the gold standard for confirming an ACL rupture. But here’s something important:

You do not need an MRI on day one unless there are red flags.

Early management is similar regardless.

Step 3: Watch For Red Flags

Most ACL tears are not medical emergencies.

But there are situations where you need urgent medical review.

Seek immediate help if you notice:

• Redness, warmth and swelling in the calf (possible clot)

• Fever or feeling unwell alongside knee swelling

• Numbness or weakness in the foot

• The knee is locked and cannot move

If you experience any of these, get assessed urgently.

Step 4: Control Swelling Immediately

Swelling is your first enemy.

Excessive joint effusion:

• Switches off your quadriceps

• Limits range of movement

• Delays recovery

• Increases long-term stiffness

Your job in the first 1–2 weeks is simple:

Reduce swelling. Regain extension. Activate the quad.

Use the PEACE approach:

• Protect (avoid twisting, pivoting)

• Elevate the leg above heart height

• Avoid anti-inflammatories early unless prescribed

• Compress with a tubigrip or sleeve

• Educate yourself on what’s happening

Ice can help manage pain, but elevation and compression are more impactful for fluid control.

Step 5: Regain Full Knee Extension ASAP

This is non-negotiable.

Loss of full knee straightening (extension) early on is one of the biggest predictors of long-term issues.

If you cannot fully straighten your knee:

• Prop your heel on a pillow and let gravity gently straighten it

• Perform towel squashes (quad activation drills)

• Avoid constantly walking with a bent knee

In my ACL Recovery Roadmap programme, Level 1 focuses heavily on:

• Full extension

• Quad activation

• Swelling control

Before worrying about surgery decisions or return to sport — you need a calm, straight knee.

Step 6: Start Early Quad Activation

After ACL injury, the quadriceps muscle shuts down.

This is called arthrogenic muscle inhibition — and it’s why your thigh can shrink alarmingly fast.

Early isometric quad exercises are critical.

Simple examples:

• Static quad squeezes

• Heel props

• Straight leg raises (if no lag present)

These should be pain-monitored and controlled.

You’re not “training hard” at this stage.
You’re reconnecting your nervous system.

Step 7: Avoid These Common Mistakes

Over the years, I’ve seen patterns.

Here’s what not to do after a suspected ACL tear:

• ❌ Testing it repeatedly by twisting

• ❌ Trying to “walk it off”

• ❌ Comparing yourself to someone else’s timeline

• ❌ Jumping straight into gym strengthening

• ❌ Ignoring instability episodes

One instability episode can damage meniscus or cartilage.

Protect the joint early.

Step 8: Decide — Operative or Non-Operative?

Not every ACL tear requires surgery.

This surprises people.

Some individuals can cope well with structured rehab alone, particularly if:

• They don’t play pivoting sports

• They have good baseline strength

• Instability episodes are minimal

Others — especially cutting/pivoting athletes — often require reconstruction.

But here’s what I tell everyone:

You do not decide this in week one.

Calm the knee first. Restore movement first. Build baseline strength first.

Then reassess.

Rehab is required either way.

Step 9: Understand That Recovery Is Criteria-Based (Not Time-Based)

One of the biggest myths in ACL rehab is timeline obsession.

“I’ll be running at 6 months.”
“I’ll be back to football at 9 months.”

This mindset increases reinjury rates.

Progression should be based on:

• Pain levels

• Swelling response

• Range of movement

• Strength testing

• Single leg control

In my clinical experience — and in my structured programme — progression is built around passing objective testing criteria before moving up levels.

It’s safer. It’s smarter. It reduces the 20% reinjury statistic.

Step 10: Take Care of Your Mental Health Early

ACL injuries are not just physical.

Research shows:

• Increased depression rates post ACL injury

• Lower psychological readiness linked to higher reinjury risk

• Fear of movement common during recovery

You will likely feel:

• Frustrated

• Impatient

• Isolated

This is normal.

Practical strategies that help:

• Journalling weekly progress

• Tracking objective improvements

• Joining a recovery community

• Visualising milestones

If you’re struggling, speak to someone. Mental readiness is as important as strength testing.

What Should You Do Today?

If you suspect you’ve torn your ACL, here’s your immediate action plan:

1. Get assessed by a professional

2. Control swelling

3. Regain full extension

4. Start quad activation

5. Avoid instability episodes

6. Don’t rush decisions

Recovery starts now — not when surgery happens.

Want a Structured Plan?

If you’re feeling overwhelmed right now, that’s completely normal.

ACL rehab can feel confusing and chaotic.

That’s exactly why I created:

The ACL Injury Survival Guide – a free, practical guide that walks you through:

• Recovery phases

• Nutrition

• Do’s and don’ts

• Mental resilience strategies

• A daily recovery checklist

It’s designed to give you clarity in the early stages.

👉 You can download it here.

And when you’re ready for a fully structured, criteria-based rehabilitation system — my ACL Recovery Roadmap takes you step-by-step through each phase with progression testing built in.

No guesswork.
No timeline obsession.
Just structured progression.

Final Thoughts

An ACL injury feels like everything just stopped.

But this is where you take control.

Early management sets the tone for everything that follows.

Calm the knee.
Restore movement.
Activate the quad.
Think long-term.

And remember — this is a marathon, not a sprint.

If you do it properly now, you massively increase your chances of coming back stronger than before.

— Arun