ACL Injury and Surgery Rehab Guide
What to Do From Day One
Momentum Physio & Rehab Group, Traralgon
Written by Chris Calabrese, Physiotherapist and Director
If you’ve just done your ACL, or you’re waiting on a scan to confirm it, this guide is for you. It covers everything from what the injury actually is, through to what returning to sport looks like and how we test it at every stage.
This isn’t a generic overview. It’s how we approach ACL rehabilitation at Momentum Physio in Traralgon, based on the evidence and the system we’ve built treating athletes and active people across the Latrobe Valley and Gippsland. If you’re looking for ACL physio in Traralgon or ACL rehab after knee reconstruction anywhere in the Latrobe Valley, this is the process we follow, from day one through to return to sport.
We’ve broken it into phases. Each phase has a goal, a set of entry criteria, and a set of exit criteria, because progression in ACL rehab is based on what your knee can do, not what the calendar says. Two people who have surgery on the same day can be in completely different phases at three months, and that’s entirely normal.
What does the ACL actually do?
The anterior cruciate ligament (ACL) sits inside your knee joint and connects your thigh bone (femur) to your shin bone (tibia). Its main job is controlling rotational stability, stopping the shin from twisting or sliding forward under the thigh, especially during cutting, landing, and change of direction.
It doesn’t do much during straight-line walking. It’s under high demand the moment you plant and twist, land from a jump, or decelerate suddenly. That’s exactly why ACL injuries happen in sport.
How do ACL tears happen?
Most ACL tears are non-contact. A player cuts, decelerates, or lands awkwardly, the knee collapses inward, the shin rotates, and the ligament can’t handle the load. You might hear a pop, feel the knee give way, and notice significant swelling within a few hours.
Contact mechanisms (like a direct tackle to the knee) do happen, but they’re less common than people think.
Common sports in our region where we see this: AFL, netball, soccer, basketball, and skiing. If you play sport in the Latrobe Valley, you know someone who’s done theirs.
What to do in the first 48-72 hours
The first thing most people notice after an ACL injury is swelling. It comes on fast, usually within the first few hours, because the ACL has its own blood supply, and when it tears, blood fills the joint. This is called a haemarthrosis, and it’s one of the clearest early signs that something significant has happened inside the knee.
The knee will feel stiff, hot, and sore to bend. Putting full weight through it is uncomfortable. Some people feel the joint is unstable, like it might give way. Others just feel pain and swelling without that sensation.
| What to do
Rest, ice, compression, and elevation still apply here. Not because they heal the injury, but because they help manage pain and swelling so you can move sooner. Ice for 15-20 minutes every couple of hours, keep the leg elevated when sitting or lying down, and use a compression bandage or tubigrip if you have one. Crutches are fine if you need them. Don’t force yourself to walk normally through significant pain, but if you can tolerate weight through the leg comfortably, gentle walking is okay. The one thing to avoid is complete rest and immobilisation. Keeping the knee completely still makes the swelling harder to shift and lets the quad shut down quickly. Light movement, gentle heel slides, lying quad contractions, calf pumps, is better than nothing from day one. |
When to see an ACL physio after injury (and do you need an MRI?)
See us as soon as you can. The first appointment isn’t about waiting for a scan, it’s about getting the knee calm, protecting your range of motion and quad function early, and starting the process in the right direction.
On scans: currently in Australia, MRI can be bulk billed through a GP referral but not through a physiotherapist. The most cost-effective path is to see your GP for the referral if you want to avoid out-of-pocket costs. That said, come and see us first. We’ll do a thorough clinical assessment, and if we have any concerns or feel imaging is warranted, we’ll refer you straight to your GP with a clear picture of what we’re looking for. That way you’re not waiting on a scan before starting rehab, and you’re not paying for one unnecessarily.
The first two weeks matter more than most people realise. Patients who start physio early consistently do better in the months that follow.
If you’re in Traralgon or anywhere in the Latrobe Valley, call us or book online and we’ll get you in quickly.
Do you need ACL surgery? Non-surgical vs surgical options
Not every ACL tear requires surgery. For some people, particularly those who aren’t returning to high-demand cutting and pivoting sports, or whose knee feels stable in day-to-day life, a non-surgical approach with structured rehabilitation can produce a good outcome.
The decision comes down to a few things: your activity goals, how unstable the knee feels, whether there are other structures involved (meniscus tears and cartilage damage are common alongside ACL injuries), and your age and overall health. This is a conversation worth having properly, with us and with an orthopaedic surgeon if surgery is on the table.
The cross bracing protocol
One development worth knowing about if you’re weighing up the surgery decision is the cross bracing protocol (CBP). This is an emerging non-surgical approach where the knee is braced at 90 degrees of flexion for the first few weeks after injury. Research from the University of British Columbia suggests that positioning the knee this way may allow the torn ACL ends to reapproximate and heal without surgical reconstruction, with a meaningful proportion of patients achieving ligament healing on MRI and returning to sport.
It’s generated serious interest in the sports medicine world and is a legitimate option worth raising with your surgeon if you’re considering going non-surgical.
It’s not suitable for everyone. Tear pattern, injury timing, and your activity goals all factor into whether you’re a candidate. It also requires strict compliance with the bracing protocol in those early weeks. If you want to explore it, ask your surgeon specifically about the cross bracing protocol and whether your tear makes you a candidate.
If surgery is the plan
One thing most people don’t realise is that surgeons don’t want to operate on a swollen, stiff, weak knee. Before your reconstruction, your surgeon will typically want to see full knee extension, minimal swelling, and reasonable quad strength. A knee that goes into surgery in poor condition tends to come out with more complications and a harder recovery.
This is called prehabilitation, and it’s one of the most valuable things you can do in the weeks between your injury and your operation.
Getting into physio early means we can work on restoring your range of motion, reducing swelling, and rebuilding quad activation before you go under. Patients who are strong and mobile heading into surgery consistently recover faster on the other side. So even if you’re waiting on a surgical date, the work starts now.
Graft choice
When you have an ACL reconstruction, the torn ligament is replaced with a graft, a piece of tendon used to reconstruct the new ligament. There are a few options, and the choice is usually made by your surgeon based on your individual situation.
The two most common are the hamstring tendon graft and the bone-patella tendon-bone (BPTB) graft. A third option, the quadriceps tendon graft, is becoming more common and some surgeons prefer it, particularly for revision surgeries.
Your surgeon will consider things like your age, your sport and activity goals, your injury history, and your occupation. One practical example: BPTB grafts can cause persistent anterior knee pain and discomfort with kneeling, which matters a lot if your job involves kneeling regularly, trades, nursing, childcare. A hamstring graft avoids that issue but has its own early rehab considerations.
Why graft choice matters for your rehab
The graft you’ve had shapes how we load your knee in the first 12 weeks. Here’s the short version.
| Graft | Healing | What it means for early rehab |
|---|---|---|
| BPTB | Bone-to-bone at the fixation points, more secure earlier (around 6-8 weeks) | We can introduce certain loads a little sooner, including more progressive hamstring loading from weeks 4-6. |
| Hamstring | Soft tissue healing into bone, slower, particularly in the first 4-12 weeks | More conservative with direct loading early. Gentle isometric work starts early; heavy loading comes later. |
| Quadriceps tendon | Becoming more common, some surgeons prefer it, particularly for revisions | Programmed to the surgeon’s protocol and your presentation. |
When you come in, tell us what graft you’ve had. It shapes how we program your first 12 weeks.
Criteria-based progression
One of the most important things to understand about ACL rehab before we get into the phases is how progression works.
Traditional rehab often runs on time. Six weeks and you move to the next phase. Twelve weeks and you start running. Nine months and you’re back. ACL rehab doesn’t work that way at Momentum, and the evidence is clear on why it shouldn’t.
Criteria-based progression means you move forward when your knee is ready, not when the calendar says so. Every transition between phases is gated by specific physical tests: range of motion, strength symmetry between legs (measured on our force plates and dynamometer), swelling levels, and functional movement quality. Hit the markers, move forward. Don’t hit them, stay and build until you do.
The re-injury rate in athletes who return to sport before clearing objective strength and performance criteria is significantly higher than those who complete the full testing battery. The knee that feels fine and the knee that tests fine are often not the same knee.
Two people with the same surgery on the same day can be in completely different places at three months. That’s entirely normal and expected, the timeline bends to the individual.
The phases at a glance
Your rehab runs across four phases. The timeframes below are a guide, not a schedule. Progression is gated by what your knee can do, not the calendar.
| Phase | Timeframe | Goal |
|---|---|---|
| Phase 1: Protection | Weeks 1-6 | Calm the knee, restore full extension and range, switch the quad back on, walk normally. |
| Phase 2: Strength and Load Tolerance | Roughly Weeks 6-16 | Build single-leg strength, load the kinetic chain properly, prepare the knee to absorb force. |
| Phase 3: Running, Hopping and Agility | Roughly Months 4-9 | Reintroduce running, then jumping, landing and change of direction, with testing at each step. |
| Phase 4: Return to Sport | Month 9 onwards | Staged return through restricted training, unrestricted training, then full play (RTR, RTT, RTP), each cleared on objective testing. |
The whole process is a 12-18 month journey, and most people sit somewhere in the middle to upper end of that depending on graft, what else was involved, and their sport.
Phase 1 – Protection (Weeks 1-6)
What we’re trying to achieve
The goal of Phase 1 is straightforward: get the knee quiet, restore normal movement, and rebuild the quad. Everything we do in this phase is working toward the exit criteria below.
ACL rehab is a 12-18 month process. There is no medal for sprinting out of the gate in week two. Phase 1 is about doing the basics exceptionally well.
Rehab modifications – when other structures are involved
ACL tears rarely happen in isolation. The same mechanism that tears the ligament often damages other structures at the same time. Your MRI and surgical report will tell us what else is going on, and it changes how we approach your rehab from day one.
| What else was involved | How it changes your early rehab |
|---|---|
| Meniscus debridement | We monitor swelling and pain more closely and progress a little more conservatively than a straightforward reconstruction. |
| Meniscal repair | Protocols vary, but often involve keeping the knee locked and non-weight-bearing for up to six weeks while the repair heals. |
| MCL involvement | Often means a limited-range-of-motion brace for several weeks. |
| Tibial plateau fracture | Bone healing comes first. Often non-weight-bearing or partial weight-bearing in a limited-ROM brace before ACL rehab begins. |
| Multi-ligament injury | Rehab is highly individual and depends on exactly what was reconstructed. |
| Extensive bone bruising | Can cause swelling and pain for up to 12 weeks, so we progress jumping and landing work more gradually. |
| Cartilage injury | Needs longer protection. We progress surfaces carefully: water first, then trampoline, then sand, then grass and hard flooring. |
Your program is built around your knee, not a generic template. If you’ve had additional surgery or additional injuries, tell us everything.
When to start physio after surgery
We want to see you within the first week post-op. Don’t wait until the swelling looks better or until you feel ready. Earlier is better.
How quickly we get started depends on a few things, how your prehab went, what we covered before surgery, and what the hospital physio worked on with you in the day or two after your operation. If we saw you pre-op and you came in strong and mobile, you’ll have a head start. If surgery was urgent or we haven’t met yet, we’re starting fresh together.
We regularly see patients who wait two or three weeks before their first appointment. By that point the kneecap is stiff and stuck down, the quad has switched off significantly, and the walking pattern has become habitual. Getting to a good outcome from that point is absolutely achievable, but it’s harder and takes longer than it needs to be.
In that first appointment we work on patella mobility, the kneecap often gets stiff after surgery and freeing it up early makes a real difference to your range of motion progress. We’ll do soft tissue work around the donor site, begin gentle ROM, and start settling the joint down.
GETTING OFF CRUTCHES
Most people want to ditch the crutches as soon as possible. That instinct is generally right, but the timing matters, and rushing it can make your gait worse before it gets better.
The goal isn’t to stop using crutches by a specific day. It’s to stop using them when you can walk without a limp. Those two things are often not the same, especially in the first two or three weeks.
We wean crutches based on two criteria: pain on full weight-bearing is manageable (a 3 out of 10 or less), and you can walk with a near-normal pattern, normal step length, normal cadence, no trunk shift. If you’re hobbling off crutches and limping around the house, you’re trading a walking aid for a compensation pattern that will take longer to fix down the track.
For most straightforward ACL reconstructions, crutches are down to one by weeks 1-2 and gone by weeks 2-4. Hamstring graft patients sometimes hold onto one crutch a little longer if the donor site makes weight-bearing uncomfortable. If you’ve had a meniscal repair or another procedure requiring protected weight-bearing, your surgeon’s protocol takes precedence and we follow that exactly.
When you come off crutches, the transition happens in a controlled way. We watch how you walk. We coach step length and heel-toe pattern. We don’t just send you home without one and assume the gait will sort itself out, because it usually doesn’t without attention.
Two approaches to Phase 1, and both are valid
Some patients come in ready to work the full picture. They want to understand how the foot and ankle feed into the knee, why hip strength matters for landing mechanics nine months from now, what the trunk is doing during sport-specific movement. For those patients, we can start building the full kinetic chain from week one.
Other patients are managing pain, disrupted sleep, time off work, family commitments, and the emotional weight of a long injury. Adding hip strengthening and foot and ankle work on top of everything else can feel like too much, and that’s completely understandable.
If that’s you, we keep Phase 1 simple. Knee extension. Quad activation. Swelling management. Walking normally. That’s enough. The kinetic chain work will come in Phase 2 when the knee is calmer and you have more capacity to take it on.
We’ll make that call together at your first appointment based on how you’re tracking and what feels manageable.
Manual therapy
Your physio appointments in the first six weeks aren’t just for checking in, there’s hands-on work at every session. Weekly we work on facilitating active and passive range of motion, patella mobilisations, hip and lower back treatment where relevant, specific knee extension work, and management of the donor site. For hamstring graft patients, the donor site at the back of the thigh can be surprisingly tender and restricted, and we address that directly.
Knee extension – the priority
Losing full extension early is one of the most common and most preventable setbacks in ACL rehab. We want you working on this multiple times throughout the day, not just at your physio appointments.
Our preference at Momentum is passive leg extension with a roll under the heel, 5 sessions of 10 minutes spread across the day, letting gravity do the work over time rather than forcing range. Calf stretching 5 times per day for 60 seconds, and standing banded terminal knee extensions (TKE) 3 times per day for 20 reps.
Quad activation
The quad shuts down quickly after knee surgery, not just because of pain, but because of a genuine neurological inhibition the brain applies as a protective response. Getting it firing again is the foundation everything else is built on.
Research suggests up to 1000 quad contractions per day produces the best neural recovery. In practice that means 10-second holds done 10 times, repeated 10 times across the day. Our preference is supine quad activation with a small rolled towel under the knee, 10 holds of 10 seconds, 5 times per day. If you can’t get a contraction against gravity lying down, we start with standing or seated variations instead.
As the quad wakes up, we progress to isometric leg extensions, starting at 90 degrees and moving toward 60 degrees over time, building to 5 holds of 45 seconds, 2-3 times per day.
Hamstring activation
Hamstring work starts early, but how we approach it depends on your graft. For hamstring graft patients, we’re conservative with load in the first four weeks while the graft integrates. We start with submaximal isometric holds at 90 and 30 degrees of knee flexion, heel slides with gentle resistance, hip bridges with feet elevated, and prone inner range hamstring curls. We’re not pulling hard on a graft that’s still healing into bone.
For BPTB graft patients, we can be slightly more progressive with hamstring loading from weeks 4-6 as bone-to-bone healing is more secure earlier.
Calf, hip, and foot/ankle work
The structures above and below the knee need attention from the start. Calf raises, seated hip abductions, and foot and ankle exercises, toe flexion, inversion, eversion, are introduced early and done for 3 sets of 15 throughout the day. These aren’t glamorous but they matter, both for overall lower limb function and as a foundation for everything that comes later.
Starting the bike
Once you hit 110 degrees of knee flexion, usually somewhere between weeks 2-4, we get you on the stationary bike. We start with zero resistance and a high seat. The goal is smooth rotation, not load. As range and tolerance improve, the seat comes down and resistance gradually increases. The bike gives you a cardiovascular option at a time when most others are off the table, and the repetitive motion encourages range of motion and circulation through the joint.
Hydrotherapy
Once your wounds have fully healed, typically around 2-3 weeks post-op, hydrotherapy is a useful option if land-based loading is still painful or swelling is persistent. The entry point here is healed wounds and Grade 1 swelling or better on land; if swelling is Grade 2 or above, we’ll continue to manage that before adding pool-based work.
Water reduces the load through the joint while still allowing meaningful movement and early strengthening. Early sessions focus on walking forwards, backwards, and sideways with attention to normal gait mechanics, mini squats within current range, knee flexion and extension with the hip fixed, and hip strengthening using a pool noodle for resistance. Balance work, single leg stance and wide base to create turbulence, is introduced as confidence builds.
Later in Phase 1, once the knee is tolerating more, we introduce jogging on the spot at low speed and faster tempo gait work. Jumping in the pool doesn’t come until Phase 2.
Gait retraining
Getting back to a normal walking pattern is a specific goal of Phase 1, not something that just happens on its own. A limp that persists past week 4-6 tends to stick around and creates compensation patterns up the chain.
We use hurdle drills to retrain normal step-through mechanics, partial step-overs, stepping between hurdles, progressing to normal gait with hurdles and then with added weight. Wall drills and static positional sense work rebuild the awareness the knee has lost. On land and in the pool, we coach step length, pelvis and trunk position, and the sounds of footfall, an uneven step sound tells us a lot about how load is being distributed.
Tools we use in Phase 1
Blood flow restriction training (BFR)
One of the biggest challenges in early ACL rehab is that the loads required to build muscle are often too high for a post-operative knee to tolerate. BFR solves that problem. By applying a cuff to the upper thigh and partially restricting blood flow out of the limb, we can drive real muscle growth with very light loads, loads that don’t stress the graft or aggravate the joint.
We can typically start BFR from around day 3-5 post-op, once the initial swelling has settled slightly. Before we use it, we screen for contraindications including deep vein thrombosis, peripheral vascular disease, certain cardiac conditions, and skin integrity issues around the cuff site. For the majority of healthy patients recovering from ACL reconstruction, it’s safe and well-tolerated.
Neuromuscular electrical stimulation (e-stim)
The quad inhibition after ACL surgery is partly neurological, the brain reduces its signal to the muscle as a protective response, and sometimes that persists even after pain and swelling have settled. E-stim applies an electrical current to the quad to produce a contraction, helping re-establish that connection. We use it alongside active quad work, not instead of it.
Mental practice and motor imagery
Research shows that vividly imagining yourself performing a movement activates the same neural pathways used during the real thing. For someone who physically can’t load the knee yet, mentally rehearsing quad contractions, leg press, or walking normally is a genuine training tool. We’ll give you specific prompts to use at home. It takes about 10 minutes and costs nothing.
Cognitive demands
Even in Phase 1 we layer in small mental challenges during exercise, counting backwards during quad sets, catching a ball during single leg balance. Sport doesn’t happen in a quiet gym. It happens fast, under pressure, with decisions happening simultaneously. We build that capacity from the start.
What we measure in weeks 2-6
Rehab without data is guesswork. From week two onwards we regularly review how the knee is responding using our force plates, tracking single leg balance and double leg squat performance, and measuring how load is distributed between legs at 0, 30, 60, and 90 degrees of knee flexion.
People compensate quietly. The force plates pick it up before it becomes a problem. These early measurements also give us a baseline, every test we do later in your rehab is compared back to where you started.
Before you move to Phase 2
Phase 2 begins when all five of the following are true. If any one isn’t there yet, we stay in Phase 1 and keep building. There’s no value in rushing this, every phase after Phase 1 depends on the foundation it creates.
Exit criteria – Phase 1
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Frequently asked questions
Do I need surgery for an ACL tear?
Not always, and the answer is becoming more nuanced as the research evolves. Some people do very well with structured rehabilitation alone, particularly those with stable knees, lower-demand activity goals, or partial tears. There’s also the cross bracing protocol, an emerging non-surgical approach where the knee is braced at 90 degrees in the early weeks post-injury to encourage the ligament to heal without surgery. Early results are promising. Come and see us first, we can help you understand your options and what the evidence says before you commit to anything.
How long does ACL recovery actually take?
A minimum of 12 months, and often closer to 18-24 months depending on your graft type, whether other structures were involved, how you respond to training, and what you’re returning to. Athletes going back to high-level cutting and pivoting sports sit at the longer end. What we won’t do is clear you based on a date, you progress when your testing says you’re ready, not when a calendar says you should be.
Can I start physio before my surgery?
Yes, and we strongly recommend it. Surgeons want to operate on a knee that has full extension, minimal swelling, and good quad strength. Getting into physio early gives us the chance to achieve all three before your operation. Patients who come in strong and mobile before surgery consistently recover faster on the other side. Don’t wait for a surgical date to get started.
How soon after surgery should I see a physio?
Within the first week, ideally. We regularly see patients who wait two or three weeks, and by that point the kneecap is stiff, the quad has significantly switched off, and the walking pattern has become habitual. Getting to a good outcome from that point is absolutely achievable, but it’s harder and takes longer than it needs to be. The work we do in that first week sets the foundation for everything that follows.
How do you know when I’m ready to move to the next phase?
We test you. At Momentum we use force plates (ForceDecks) and a dynamometer (ForceFrame) to measure actual strength output and limb symmetry, not just how the knee feels. Feeling ready and testing ready are often not the same thing. Before you move from one phase to the next, your knee needs to hit specific numerical benchmarks: strength symmetry between legs, acceptable swelling levels, and movement quality on performance tasks. We’ll show you exactly where you sit against those benchmarks at every testing session.
📱 Video: ForceDecks single leg squat test – show the output screen and explain what the limb symmetry index number means in plain language.
What is blood flow restriction training and is it safe?
BFR involves applying a cuff to the upper thigh and partially restricting blood flow out of the limb during exercise. This allows you to build muscle with very light loads, loads that a post-operative knee can actually tolerate. It’s well-researched, widely used in sports rehab, and safe for the majority of patients. Before we use it, we screen for contraindications including blood clotting conditions, vascular issues, and certain cardiac conditions. For most otherwise healthy patients recovering from ACL reconstruction, it’s one of the most useful tools we have in the early weeks.
My surgeon said I’ll be back playing in nine months. Is that realistic?
Nine months is a commonly cited figure and for some people it’s achievable, but it’s a starting point for conversation, not a guarantee. Re-injury rates are significantly higher in athletes who return to sport before clearing objective strength testing, regardless of how many months have passed. We don’t work against your surgeon’s timeline, we work with it while making sure your knee is objectively ready when that date arrives. If the testing says you’re ready at nine months, great. If it doesn’t, we’ll tell you that clearly and show you what still needs work.
Written by Chris Calabrese, Physiotherapist and Director, Momentum Physio & Rehab Group, Traralgon.