Written and clinically reviewed by Shivaliba Zala, HCPC-registered physiotherapist (PH155757)

Reviewed 8 September 2026

After an ACL reconstruction exercises

An ACL reconstruction replaces the torn ligament with a graft, usually taken from your own hamstring tendons or the tendon below the kneecap, threaded through tunnels in the bone and fixed in place. The operation restores the mechanical restraint. The outcome, though, is decided by a long and structured rehabilitation - typically nine to twelve months before a return to pivoting sport.

The graft is not at its strongest on day one. It is at its most vulnerable in the middle weeks and months, as the body remodels it, which is why the milestones are spaced the way they are and why the protocol is not something to run ahead of. Early rehabilitation protects the graft while restoring full straightening, settling swelling, and switching the quadriceps back on - it shuts down fast after surgery and is slow to return.

The early weeks are demanding and progress can feel slow, particularly in the second and third month when the knee feels fine for walking but is nowhere near ready for sport. Quadriceps strength is the single best predictor of how things end up, which is why so much of the middle phase is spent on it. The final phase adds power, hopping and change of direction, and tests readiness against objective criteria rather than the calendar.

This programme follows that arc as a general framework. Always work to the specific protocol and milestones set by your surgeon and treating physiotherapist, which take priority over any general plan, and tell them promptly if the knee swells sharply, locks, or gives way.

Who this programme is for

People recovering from ACL reconstruction surgery who are following their surgeon's rehabilitation protocol. In the early weeks, follow the programme your hospital team gave you. Sessions with us start once your surgical team has confirmed you have no restrictions. The early-phase exercises below are shown for reference only; this is a general framework to support that protocol, not a replacement for individualised post-operative physiotherapy.

Get urgent help now if

Sudden breathlessness or chest pain - call 999 or go to A&E, this could be a blood clot in the lungs, especially if you also have pain or swelling in a leg. Do not drive yourself.
The area is hot, very swollen and red, especially if you also feel feverish or unwell - go to A&E now, or call NHS 111 straight away if you are not sure where to go. Do not drive yourself if you feel very unwell.

Get checked by a clinician first if

The knee locks and cannot be fully straightened - possible graft or meniscal problem, seek prompt review
Throbbing or cramping pain, swelling, warmth or redness in one calf or leg with no clear cause - ask for an urgent GP appointment or call NHS 111 to rule out a blood clot
Wound that opens, leaks, or becomes increasingly red, hot and painful, with or without a fever - possible infection: contact your surgical team, or ask for an urgent GP appointment or call NHS 111
A sudden pop, giving way, or rapid swelling after a twist or fall - seek assessment to check the graft
The pain followed a significant accident, fall or direct blow and you have not been checked over
You feel unwell with the pain - a fever, night sweats, or losing weight without trying
Pain that is severe, steadily getting worse, or keeps you awake every night and does not ease with a change of position

The staged programme

Stage 1

Early recovery

For reference only: in the early weeks, follow the programme your hospital team gave you. Sessions with us start once your surgical team has confirmed you have no restrictions. Hospital programmes at this stage usually aim to restore full straightening, control swelling, reactivate the quadriceps, and regain a normal walking pattern within any brace or weight-bearing limits you have been given.

Quad SetsGently tightening the thigh muscle without bending the knee, reactivating the quadriceps in the earliest days after surgery.Post-opEarly rehabView details

Straight Leg RaiseStrengthens the thigh muscle while keeping the knee straight, moving as guided.KneeEarly rehabView details

Heel SlideGently restores knee bending range through a slow, controlled sliding motion.KneeEarly rehabView details

Ankle Pumps (Post-Surgery)Regular ankle pumping in bed to promote circulation and reduce clot risk in the first days after surgery.Post-opEarly rehabView details

Stage 2

Build strength

From around 6 to 12 weeks. Progress double and single-leg strengthening, stationary cycling, and controlled knee extension work, building load steadily as the graft matures.

Resisted Knee Extension (Post-ACL)Light resisted knee straightening within the surgeon's protocol, rebuilding quadriceps strength after graft healing time.Post-opStrength phaseView details

Mini SquatBuilds functional leg strength through a small, controlled bend at the knees and hips.KneeStrength phaseView details

Terminal Knee Extension (Band)A resisted band pulling the knee into slight flexion while the quad straightens it, targeting the final degrees of extension.KneeStrength phaseView details

Stationary BikeSupports gentle, low-impact movement to build knee range and general fitness.KneeMobility phaseView details

Stage 3

Power and control

From around 3 to 6 months, once strength is developing and roughly symmetrical. Add single-leg strength, balance on unstable surfaces, and progressive hopping and landing drills.

Split SquatA staggered-stance squat building single-leg strength and control, a key step before returning to sport.KneeReturn to functionView details

Step-UpStepping up onto a low step with control, building single-leg strength for stairs and functional movement.KneeStrength phaseView details

Single Leg BalanceImproves standing balance and confidence, with hand support nearby if needed.BalanceMobility phaseView details

Box Step-DownA slow, controlled step down from a low box, building eccentric quad control that protects the kneecap joint.KneeStrength phaseView details

Stage 4

Return to sport

Return to pivoting sport is a shared decision with your surgeon and physiotherapist, usually not before 9 to 12 months. It is guided by criteria: quadriceps and hamstring strength within 90 percent of the other leg, a hop test battery within 90 percent symmetry, well-controlled landing and cutting, completion of a full return-to-training progression, and psychological readiness. Meeting the criteria matters more than the month.

Return-to-Sport Readiness CircuitA combined strength, balance and agility circuit used as a final check before clearing return to a chosen sport.GeneralReturn to functionView details

Single Leg Balance on FoamStanding on one leg on an unstable surface, retraining ankle proprioception for sport and uneven ground.AnkleReturn to functionView details

Return-to-Function Strength CircuitA combined circuit of functional strength movements marking the transition back to normal activity levels.Post-opReturn to functionView details

How long recovery takes

Recovery after ACL reconstruction is long and guided by testing, and your surgical team's protocol comes first. Rehab starts once your surgical team has confirmed you have no restrictions. It depends on your condition; your physiotherapist will give you an estimate after your assessment. We review your progress regularly and adjust your plan.

Knowing when to progress

Follow your surgeon's protocol for the milestones. In the early weeks, your hospital team guides your rehab and any weight-bearing and brace instructions; sessions with us start once your surgical team has confirmed you have no restrictions. From the strength phase on, use side-to-side symmetry as the main progression gauge, and do not begin cutting and pivoting drills until strength is close to matched.

Common questions

Why does it take a whole year?

The graft has to revascularise and remodel into a functioning ligament, which takes many months, and re-injury risk stays high until strength and control are fully restored. Returning before around 9 months, or before meeting criteria, sharply raises the chance of a re-tear.

When can I drive?

Usually around 4 to 6 weeks for an automatic car if the right leg was operated on, or sooner for the left leg, provided you can control the vehicle and perform an emergency stop. Check with your surgeon and insurer.

Is it normal for my knee to still feel different months later?

Yes. Some stiffness, occasional swelling after hard sessions, and a feeling that the knee is not quite your own are common through the first year and usually fade. Persistent locking or giving way is not normal and should be reviewed.

How do I lower the risk of injuring the other knee?

Complete criteria-based rehab, keep training both legs equally, and continue a maintenance programme of strength and landing control after you return. The other knee is also at raised risk in the first two years.

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