ACL Reconstruction Recovery: Rehabilitation Phases Explained

Your phase-by-phase guide to ACL reconstruction recovery: what happens in each stage of rehab, the milestones that move you forward, and the equipment that makes the first weeks at home easier.

Written by Supply Physical Therapy | Reviewed by Dr. Dina Khentigan, DNP | Updated October 2026

If you've just torn your ACL or have surgery on the calendar, you've probably heard a lot of numbers. Six weeks. Six months. Nine months. A year.

Here is the more useful question to answer first:

What has to happen in each phase of ACL rehab before you're ready for the next one?

Most people move through five or six rehabilitation phases after ACL reconstruction, from protecting the graft in the first two weeks to returning to sport, usually no sooner than nine months after surgery. The calendar gives a rough guide, but progress is based on milestones: full knee extension, controlled swelling, quad strength, and passing return-to-sport testing. Your surgeon and physical therapist set the plan, and it may differ from what's below.

In this guide, we'll cover:

• What happens during ACL reconstruction and why the graft type matters for rehab
• Each rehabilitation phase, with goals, common exercises, and milestones to move on
• What the research says about timing and returning to sport
• The equipment that helps at home, from cold therapy to bracing
• Common mistakes, warning signs, and answers to the questions patients ask most

Cold therapy is part of most ACL recovery plans in the early weeks. Common options include the Breg Polar Care Cube with Knee Pad, Breg Polar Care Kodiak with Knee Pad, DonJoy IceMan CLEAR3 with McGuire Knee Pad, Aircast Knee Cryo Cuff, and cold plus compression systems like the Breg Polar Care Wave and Omni Ice Pulse Compression.

Prefer to watch? See how to apply a cold therapy knee pad after surgery on our Movement Health YouTube channel.

At Supply Physical Therapy, we help patients prepare for knee surgery and set up their home recovery before day one. Here's how the phases compare.

ACL Rehab Phases at a Glance

*Timing is a guide only. Graft type, meniscus repair, and your surgeon's protocol all change the timeline. You move to the next phase when you meet its milestones, not when the calendar says so.

Quick recommendations

• Before surgery: Start prehab, set up your home recovery station, and have your cold therapy machine and skin barrier ready.
• Weeks 0 to 2: Your main jobs are getting the knee straight, waking up the quad, and managing swelling with cold therapy and elevation.
• Weeks 2 to 12: Follow your physical therapy plan closely. This is where strength and normal walking come back.
• Months 3 and beyond: Don't skip testing. Feeling good is not the same as being ready to cut and pivot.

1. What Happens During ACL Reconstruction?

The anterior cruciate ligament (ACL) runs through the middle of the knee and keeps the shin bone from sliding forward and twisting under the thigh bone. A torn ACL does not heal well on its own, so surgeons replace it with a graft.

Common graft types

• Patellar tendon (bone-patellar tendon-bone): Taken from the front of your own knee. Strong and well studied, but kneeling can be sore for a while.
• Hamstring tendon: Taken from the back of your own thigh. Hamstring strengthening is often delayed a few weeks to let the donor site heal.
• Quadriceps tendon: Taken from above the kneecap. Used more often in recent years.
• Allograft: Donor tissue. No second incision, but often avoided in young, active athletes.

Why the graft matters for rehab

The graft is weakest in the weeks after surgery while it heals into the bone and remodels. Each graft type also leaves a donor site that needs its own care. That's why your physical therapist may hold some exercises back or change the order.

Why rehab matters as much as surgery

Surgery replaces the ligament. Rehab restores the motion, strength, and control that protect it. Most of the work happens in the months after surgery, much of it at home.

2. The ACL Rehabilitation Phases Explained

Phase 0: Prehab (before surgery)

The knee you bring into surgery shapes the knee you come out with. Many surgeons wait until swelling has calmed down and the knee straightens fully before they operate.

Goals: Full extension, reduced swelling, a strong quad contraction, and normal walking if possible.

Common exercises: Quad sets, straight leg raises, heel props for extension, heel slides, and stationary biking if your clinician allows it.

Get ready at home: Set up a recovery station by your bed or couch. Practice with crutches. Unbox your cold therapy machine and do a test run before surgery day.

Phase 1: Protection and early motion (weeks 0 to 2)

The first two weeks are about protecting the graft and winning back extension.

Goals: Control pain and swelling, get the knee fully straight, and turn the quad back on.

Common exercises: Quad sets, straight leg raises, ankle pumps, heel slides, and heel props or prone hangs for extension.

Equipment: Crutches and a brace if your surgeon prescribes them. A cold therapy machine with a knee pad is often used for swelling, with a sterile dressing or skin barrier between the pad and skin. Follow the 20 minutes on, 20 minutes off protocol unless your care team gives you a different schedule.

Milestones to move on: Full extension, a straight leg raise with no knee bend ("lag"), and about 90° of bend.

Phase 2: Early strength and mobility (weeks 2 to 6)

This is where walking comes back and the knee starts to feel like yours again.

Goals: Walk normally without crutches, keep full extension, build bend toward 120° or more, and rebuild quad strength.

Common exercises: Mini squats, step-ups, bridges, calf raises, stationary bike, balance work on two legs, then one.

Milestones to move on: Normal walking without a limp, minimal swelling, and good control on a step.

Phase 3: Strengthening and control (weeks 6 to 12)

The graft is still remodeling, but you can load the leg more.

Goals: Full range of motion, stronger quads and hamstrings, and steady single-leg balance.

Common exercises: Leg press, split squats, single-leg balance, step-downs, and resistance band work for the hips.

Milestones to move on: No swelling after workouts, full motion, and good knee position on single-leg squats.

Phase 4: Running and power (months 3 to 6)

Many patients feel close to normal here. The graft is not.

Goals: Start a walk-to-run program, then add jumping, landing, and agility drills.

Common exercises: Treadmill or track running progressions, double-leg then single-leg hops, lateral shuffles, and deceleration drills.

Milestones to move on: Quad strength around 70 to 80% of the other leg before running, and clean landing mechanics before cutting.

Phase 5: Return to sport (months 6 to 9 and beyond)

The last phase turns strength into sport.

Goals: Sport-specific drills, cutting and pivoting, then full practice and competition.

Testing: Strength testing, hop testing, movement quality, and how confident you feel about the knee.

Bracing: Some surgeons recommend a functional knee brace when you return to cutting and pivoting sports. Ask yours before you buy one. We carry the DonJoy Playmaker II Knee Brace.

Milestones to move on: Passing your return-to-sport tests and your surgeon's clearance, usually no sooner than 9 months after surgery.

3. What Does the Research Say About ACL Rehab Timing?

Milestones beat the calendar

Modern ACL rehab is "criteria-based." You progress when you pass the tests for each phase, not on a fixed date. Clinical practice guidelines for ACL rehabilitation support this approach.

Waiting until 9 months lowers reinjury risk

In the Delaware-Oslo ACL Cohort study (Grindem and colleagues, British Journal of Sports Medicine, 2016), athletes who returned to pivoting sports before 9 months had a much higher reinjury rate. Each month they waited, up to 9 months, lowered their risk.

Passing return-to-sport testing matters

In a study of professional male athletes (Kyritsis and colleagues, British Journal of Sports Medicine, 2016), those who returned without meeting discharge criteria had about four times the risk of graft rupture.

Prehab pays off

The same Delaware-Oslo research group found that patients who completed preoperative rehab reported better knee function two years after surgery than those who did not.

Cold therapy helps with pain in the early weeks

A meta-analysis of cryotherapy after ACL reconstruction (Raynor and colleagues, Journal of Knee Surgery, 2005) found less postoperative pain with cold therapy. It did not find a clear effect on range of motion.

What this means for you

• Expect your therapist to test you before each step up, especially running, jumping, and return to sport.
• Treat 9 months as a floor for cutting and pivoting sports, not a goal.
• Use cold therapy for pain and comfort in the early weeks, alongside your exercises, not instead of them.

4. Recovery Equipment: Cost Upfront and Over Time

*Prices as of October 2026. Prices can change.

Hidden costs to consider

• Skin barriers and sterile dressings. Non-sterile knee skin barriers for the Breg Cube are $19.99. Cube sterile knee dressings are $35.99.
• Ice. Several fills a day in the first two weeks adds up. Reusable ice bags ($28.99 for 8) cut down on store trips.
• Insurance. Most plans don't cover cold therapy machines. Check before surgery.
• Time. Physical therapy usually runs two to three visits a week early on. Budget for copays and drive time.

5. Extension, Swelling, and Quad Control: The Three Things That Matter Most

Full extension

A knee that won't straighten all the way changes how you walk and loads the front of the knee. Extension is usually the first priority. Heel props and prone hangs are common ways to work on it. Never put a pillow under the knee to sleep.

Swelling

Swelling shuts down the quad and limits motion. Elevation, cold therapy, compression, and pacing your activity all help. Swelling that gets worse after a workout is a sign you did too much.

Quad control

After ACL surgery, the brain partly switches off the quad. Quad sets and straight leg raises in the first days turn it back on. Quad strength is also one of the main measures used to clear you for running and sport.

Range of motion

Bend comes back more gradually than extension. Most protocols aim for about 90° by week 2 and 120° or more by week 6, but your surgeon may limit bend if you also had a meniscus repair. See our 10 ways to improve range of motion during recovery.

Walking

You'll likely use crutches for the first one to several weeks. Wean off when you can walk without a limp, not just when you can bear weight.

6. Safety: Warning Signs After ACL Surgery

Call your surgeon right away if you notice

• Calf pain, swelling, warmth, or redness in the lower leg, which can signal a blood clot
• Chest pain or shortness of breath. Call 911.
• Fever, or redness, warmth, or drainage at the incision
• A sudden increase in swelling or pain, or the knee giving way
• Numbness or tingling that doesn't go away

Use cold therapy safely

• Always use a barrier. Put a sterile dressing over a fresh incision, or a non-sterile skin barrier once the skin is closed. Read why you should always use a sterile pad with cold therapy.
• Follow 20 minutes on, 20 minutes off unless your care team gives you a different schedule.
• Be careful after a nerve block. If your leg is numb, you may not feel the cold getting too strong.
• Check your skin every session. Stop if you see blisters, color changes, or numbness that lasts.
• Don't sleep with the machine running unless your surgeon and the instructions say it's OK.

Protect the graft

• Don't skip phases or add pivoting, jumping, or running before you're cleared.
• Wear your brace and use crutches as long as your surgeon tells you to.

7. How Your Situation Can Change the Plan

8. What to Buy Before ACL Surgery

Essential checklist

• A cold therapy machine with a knee pad your surgeon approves, such as the Breg Polar Care Cube with Knee Pad
• The right knee pad size. Use our Breg Polar Care Cube knee pad size guide.
• Sterile dressings for the first days and non-sterile skin barriers for later
• Reusable ice bags or a freezer plan for ice
• Crutches and a brace if your surgeon prescribes them
• Pillows to prop the heel for extension, not the knee
• A recovery station with your phone, water, medications, and exercise sheet in reach. See our home recovery station tips.

9. When Should You Order?

Order your cold therapy machine one to two weeks before surgery. That gives you time to check the pad size, do a test run, and contact us if anything is missing. Supply Physical Therapy ships same or next day from Charlotte, North Carolina, but don't count on a last-minute order arriving before you get home from surgery.

10. How to Use Recovery Equipment Safely

Cold therapy machines

1. Fill the cooler to the marked lines with ice and water. See how to use the Breg Polar Care Cube.
2. Place a sterile dressing or skin barrier on the knee.
3. Wrap the knee pad snugly, but not so tight it cuts off circulation.
4. Run 20 minutes on, 20 minutes off, and check your skin each session.
5. Elevate the leg with the heel propped and the knee straight.

Gravity cold cuffs

The Aircast Knee Cryo Cuff fills by raising the cooler and drains by lowering it. Refresh the water when it warms up, and follow the same barrier and skin-check rules.

Cold plus compression systems

Use active compression only if your surgeon recommends it. People with some blood clot or circulation risks may be told to avoid it.

Braces

Wear a post-op brace exactly as prescribed, including any locked-straight settings for walking or sleeping. A functional brace for sport is a later-phase decision.

11. Common Mistakes During ACL Recovery

Mistake 1: Putting a pillow under the knee

It feels comfortable, but it lets the knee stiffen in a bent position. Prop the heel instead.

Mistake 2: Chasing bend before extension

Full extension comes first. Losing it early is much harder to fix later.

Mistake 3: Doing too much in weeks 2 to 6

Feeling better isn't the same as being healed. Watch for swelling the day after a workout.

Mistake 4: Skipping the home exercises

Therapy visits set the plan, but most of the work happens at home between visits.

Mistake 5: Running or jumping before you're cleared

The graft is still remodeling at 3 to 6 months, even when the knee feels normal.

Mistake 6: Returning to sport on a date instead of a test

Nine months is a minimum for most cutting sports, and you still need to pass return-to-sport testing.

Mistake 7: Using cold therapy without a barrier

Cold injury can happen fast, especially when the leg is numb. Always use a dressing or skin barrier.

Mistake 8: Buying the wrong knee pad

Pads only fit their own machine family, and size matters. Check fit before surgery day.

12. Frequently Asked Questions

How long does ACL reconstruction recovery take?

Most people walk normally within about 6 weeks and return to everyday activities in 3 to 4 months. Return to cutting and pivoting sports usually takes at least 9 months.

What are the phases of ACL rehab?

Most programs use five or six phases: prehab, protection (weeks 0 to 2), early strength and mobility (weeks 2 to 6), strengthening (weeks 6 to 12), running and power (months 3 to 6), and return to sport (months 6 to 9 and beyond).

What is the hardest part of ACL recovery?

For many people it's the first two weeks, when pain, swelling, and getting the knee straight take the most effort. Later, staying patient through months 3 to 6 is the challenge.

When can I walk without crutches after ACL surgery?

Often within 1 to 4 weeks, once you can walk without a limp. A meniscus repair can extend this.

When can I drive after ACL surgery?

It depends on which knee, your car, and whether you're off opioid pain medication. Ask your surgeon.

When can I start running after ACL reconstruction?

Usually around 3 to 4 months, once you meet your therapist's strength and movement criteria.

How much should my knee bend at 2 weeks?

Many protocols aim for about 90° by week 2, with full extension. Your surgeon may limit bend if you had a meniscus repair.

Should I use ice or a cold therapy machine after ACL surgery?

Either can work if your surgeon approves it. A machine with a knee pad keeps a steady temperature and covers the whole knee without swapping packs.

How often should I ice after ACL surgery?

A common approach is 20 minutes on, 20 minutes off, with a barrier between the pad and skin. Follow your care team's schedule.

Can I sleep with a cold therapy machine on?

Only if your surgeon and the manufacturer's instructions say it's OK. Otherwise, turn it off before you sleep.

Do I need a knee brace after ACL surgery?

Some surgeons use a post-op brace for the first weeks and others don't. Functional braces for sport are a separate decision later on.

When can I return to sports after ACL surgery?

Usually no sooner than 9 months, after passing return-to-sport testing and getting your surgeon's clearance.

13. Final ACL Recovery Checklist

Before surgery, confirm:

• I know my graft type and whether I'm having a meniscus repair.
• I've started prehab and can fully straighten my knee.
• I have my physical therapy visits scheduled.
• I have a cold therapy machine, the right knee pad size, and a dressing or skin barrier.
• I have crutches and a brace, if prescribed.
• I've set up a recovery station at home.
• I know the warning signs that mean I should call my surgeon.

Final Verdict: How to Get Through Each Phase of ACL Rehab

ACL recovery is a series of milestones, not a countdown.

Weeks 0 to 2: Get the knee straight, wake up the quad, and keep swelling down with cold therapy, elevation, and rest.

Weeks 2 to 12: Rebuild normal walking, motion, and strength with your physical therapist.

Months 3 to 6: Earn running and jumping by meeting strength and movement criteria.

Months 6 to 9 and beyond: Return to sport only after passing testing and getting your surgeon's clearance.

The right equipment won't speed up graft healing, but it can make the hardest early weeks at home easier to manage.

Shop ACL Recovery Equipment at Supply Physical Therapy

At SupplyPT.com, we carry cold therapy machines, knee pads, sterile dressings, skin barriers, and knee braces from Breg, DonJoy, Aircast, and Omni Ice.

• Breg Polar Care Cube with Knee Pad
• Breg Polar Care Kodiak with Knee Pad
• DonJoy IceMan CLEAR3 with McGuire Knee Pad
• Aircast Knee Cryo Cuff & IC Cooler
• Breg Polar Care Wave with Knee Pad
• Omni Ice Pulse Compression with Knee Pad
• Cold Therapy Skin Barriers
• DonJoy Playmaker II Knee Brace

Not sure which setup fits your surgery? Contact our team before you order.

Protect the graft. Hit your milestones. Follow your recovery plan.

Medical disclaimer: This article is for educational purposes only and is not medical advice. ACL rehabilitation timelines vary. Follow your surgeon's and physical therapist's instructions and the manufacturer's current instructions for any device.

Sources and Further Reading

1. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. British Journal of Sports Medicine, 2016.
2. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. British Journal of Sports Medicine, 2016.
3. Grindem H, Granan LP, Risberg MA, et al. How does a combined preoperative and postoperative rehabilitation programme influence the outcome of ACL reconstruction 2 years after surgery? British Journal of Sports Medicine, 2015.
4. Raynor MC, Pietrobon R, Guller U, Higgins LD. Cryotherapy after ACL reconstruction: a meta-analysis. Journal of Knee Surgery, 2005.
5. van Melick N, et al. Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. British Journal of Sports Medicine, 2016.
6. Ardern CL, et al. Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis. British Journal of Sports Medicine, 2014.
7. Supply Physical Therapy. How to Size Breg Polar Care Cube Knee Pads & Avoid Cold Injury.
8. Supply Physical Therapy. Why You Should Always Use a Sterile Pad with Cold Therapy.
9. Supply Physical Therapy. How to Use the Breg Polar Care Cube: Setup, Ice & Safety Tips.
10. Supply Physical Therapy. Complete Knee Replacement Recovery Guide.