MSK Rehabilitation, Patient Guide

ACL rehab: what an ACL injury is, your options and the road back to sport

Written by Elliot Stubbs, BSc (Hons) Physiotherapy, 13 years in MSK practice. Updated 14 October 2026.

ACL rehab is a staged programme that rebuilds movement, strength and confidence after an anterior cruciate ligament injury, with or without surgery. It moves from settling swelling and straightening the knee, through progressive gym-based strength work, to running, jumping and sport-specific training. Return to sport should be decided by meeting clear criteria, not just by how many months have passed.

What is the ACL?

The anterior cruciate ligament (ACL) is one of the main ligaments inside the knee. It runs diagonally through the middle of the joint, from the thigh bone to the shin bone. Its job is to stop the shin bone sliding too far forwards and to help control the knee when you twist, turn or land.

Injuries range from a sprain to a complete tear, sometimes with damage to the meniscus (the cartilage cushions in the knee) or other ligaments.

How does an ACL injury usually happen?

Many ACL injuries involve no contact at all, for example:

Planting your foot and changing direction sharply, such as sidestepping in rugby or turning with the ball in football
Landing awkwardly from a jump, especially with the knee collapsing inwards
A tackle that forces the knee sideways

People often describe a pop or the knee shifting, then pain and difficulty carrying on. The knee commonly swells quickly, within a few hours, from bleeding inside the joint. Later, the knee may give way when you turn or pivot, even once walking feels normal.

How is an ACL injury diagnosed?

A physiotherapist, GP or emergency clinician can examine the knee with hands-on tests that check how much the shin bone moves. These can be tricky while the knee is very swollen, so a repeat examination once it settles is often more informative.

An MRI scan is commonly used to confirm a tear and check for other damage inside the knee. If an ACL injury is suspected, a physiotherapist can explain the findings and advise on getting an orthopaedic opinion, usually arranged through your GP.

Do you need surgery for a torn ACL?

Not everyone does. There are two broad paths, both valid for different people, and the choice is made with an orthopaedic surgeon based on your knee, sport and goals.

Rehab first

Some people do well with structured rehab and no reconstruction, particularly if they don't plan to return to twisting and turning sports, or their knee doesn't keep giving way once it is strong. Choosing rehab first doesn't close the door on surgery: if the knee still feels unstable after a good period of rehab, reconstruction can be considered later.

ACL reconstruction

In a reconstruction, the surgeon replaces the torn ligament with a graft, usually taken from a tendon elsewhere in your leg. It is often recommended for people returning to pivoting sports like rugby and football, whose knee repeatedly gives way, or who have certain other knee injuries.

Rehab matters on either path. Before surgery, a period of prehab (getting the swelling down, the knee fully straight and the thigh muscles working) is commonly recommended. Our guide to rehab after surgery covers what to expect after an operation more generally.

What are the stages of ACL rehab?

You progress through each stage by meeting its goals, not simply when a set number of weeks has passed. Any specific guidelines from your surgeon always come first.

Settle swelling and restore movement. Getting the knee fully straight, improving how far it bends, switching on the quadriceps (the big muscles at the front of the thigh) and walking without a limp.
Build strength. Progressive loading of the quads, hamstrings, hips and calves, building towards heavier and single-leg work.
Return to running. Once the knee is settled, moves well and is strong enough, running is reintroduced gradually. The principles in our guide to returning to running after injury apply here too.
Jumping and landing. Landing softly with good knee control, then hopping and single-leg landings.
Change of direction and sport-specific work. Cutting, sidestepping and decelerating, then drills from your sport, building up to contact for rugby.
Return to sport. Rejoining full team training first, then matches.

Why does gym-based strength work matter so much?

After an ACL injury, and especially after surgery, the thigh muscles on the injured side lose a lot of strength, which can be slow to return. Home exercises are a useful start, but rarely load the muscles enough on their own for running, landing and tackling.

That is why gym-based work, such as leg press, squats, split squats and hamstring exercises, progressed steadily over months, is the backbone of most ACL rehab. Sessions here take place in a fully equipped gym with 1:1 guided rehab, so heavier strength work is supervised and progressed at the right pace.

How long does ACL rehab take?

ACL rehab takes months, not weeks. After a reconstruction, a return to pivoting and contact sports like rugby and football commonly takes nine months or more. Rehab without surgery also usually takes several months of consistent work.

Timelines vary with the injury, any other damage inside the knee and how consistently rehab is done. Rushing back before the knee is ready is thought to increase the risk of injuring it again.

How do you know you're ready to return to sport?

Return-to-sport decisions are best based on criteria, agreed with your physio and, where relevant, your surgeon. These commonly include:

No ongoing swelling, and full or near-full movement
Thigh and hamstring strength close to the uninjured side, ideally measured rather than guessed
Hop and landing tests performed well, with good control on each leg
Completing full training, including change of direction and contact where relevant, without the knee reacting
Feeling confident in the knee

When to get urgent help

Call 999 or go to A&E if: the knee looks deformed, you can't put any weight on it, or your foot or lower leg goes cold, pale or numb after an injury. Call 999 if you have calf pain or swelling with chest pain or breathlessness.

Call 111 or get seen urgently if: your knee swelled up rapidly after a twist or fall; it is locked and won't straighten; it becomes hot, red and swollen, especially if you feel unwell or have a temperature; or, after surgery, your wound looks red or is leaking, or your calf becomes painful or swollen.

After surgery, if something doesn't feel right, contact your surgical team first. A knee that keeps giving way in everyday life is worth discussing with your GP or surgeon. For more general knee aches, see our guide to knee pain when bending.

ACL rehab for rugby and football players in Wymondham

If you play rugby or football in Wymondham, Norwich or South Norfolk, whether you've just hurt your knee, are waiting for surgery or are months into your rehab, Elliot works with players at Suggs Gym on Tuesday evenings. No GP referral is needed, and you can check the assessment and follow-up prices before you book an assessment.

Frequently asked questions

Can you walk with a torn ACL?

Often, yes. Once the swelling settles, many people walk fairly normally, which is one reason ACL injuries are sometimes missed. Walking comfortably doesn't mean the knee is stable for twisting, turning or landing, so it's worth getting it assessed.

Do I need surgery for a torn ACL?

Not always. Some people do well with structured rehab alone, while others, especially those wanting to return to pivoting sports or whose knee keeps giving way, are often advised to have a reconstruction. It's a decision to make with an orthopaedic surgeon, and good rehab matters either way.

How long after ACL surgery can I play rugby or football again?

Returning to pivoting and contact sport commonly takes nine months or more after a reconstruction. The decision should be based on meeting strength, hopping and movement criteria, not just the date on the calendar.

Should I do rehab before ACL surgery?

Often, yes. Getting the swelling down, the knee fully straightening and the thigh muscles working before surgery is commonly recommended and tends to make early recovery easier. Your surgeon and physio can advise on your own situation.

Do I need a GP referral to see a physio for ACL rehab?

No. You can book a physiotherapy assessment directly without seeing your GP first. If you've had surgery, bring any rehab guidelines from your surgical team.

This guide is general information written by a physiotherapist, not a substitute for individual assessment. After surgery, always follow your surgical team's guidelines, and if you're unsure about any of the warning signs above, seek medical advice rather than waiting for an appointment.