Anterior Cruciate Ligament (ACL) Reconstruction
Five-phase pathway after ACL reconstruction in the skeletally mature patient: from early post-operative recovery to return to team, with objective criteria between phases.
Return to pivoting sport: not before 9 months, typically 9-12 months
These documents are protocol templates for information and education only: they do not replace the rehabilitation prescription for the individual case. Timing, loading and progressions must always be adapted to the patient, the lesion pattern, the surgical technique used and the clinical course, in collaboration between orthopaedic surgeon, physiotherapist and, where appropriate, physiatrist. Progression is driven by objective criteria, not by the calendar alone.
The anterior cruciate ligament prevents anterior translation of the tibia on the femur and controls rotation. After reconstruction, the graft undergoes a biological process of integration and revascularisation that takes time and cannot be accelerated: rehabilitation supports it, it does not force it.
The pathway is divided into phases defined by goals to be met and by the minimum time required for biological healing. Progression between phases occurs when objective criteria are met, not simply when a given number of weeks has passed.
Respecting return-to-sport decision rules (passing the test battery and waiting at least 9 months) substantially reduces re-injury risk: the Delaware-Oslo cohort reported a reduction of around 84%, with risk decreasing progressively for each month of delay up to 9 months.
Key parameters
- Weight bearing
- Progressive weight bearing as tolerated from day one, unless the surgeon indicates otherwise (associated lesions, specific fixation).
- Brace
- Not routinely required; when prescribed, usually locked in extension for walking in the first weeks.
- ROM
- Full extension (0°) is the absolute priority; 90° flexion within 2 weeks, 125°+ within 6-8 weeks.
- Straight-line running
- Not before month 3, and only with full ROM, no effusion and quadriceps strength ≥70-80% of the contralateral side.
- Daily activities
- Sedentary work after 7-10 days; driving at 30-45 days; swimming and showering after wound healing (15-20 days).
- Return to sport
- Pivoting sport not before 9 months, with the full test battery passed (LSI ≥90%).
Loading timeline
Range of motion progression
Milestones at a glance
- Day 1Full extension and quadriceps contraction
- 2 weeks90° flexion, walking without crutches
- 6 weeksFull ROM, bike with resistance
- 3 monthsStart straight-line running
- 6 monthsPlyometrics, agility, strength ≥90%
- 9-12 monthsReturn to pivoting sport
Phases of the pathway
Phase 1 — Early post-operative recovery
Weeks 0-2
Goals
- •Achieve and maintain full knee extension
- •Reduce and control joint effusion
- •Restore voluntary quadriceps activation
What to do
- •Quadriceps isometrics in full extension, straight leg raise without extension lag
- •Patellar mobilisations, cryotherapy and compression, elevation
- •Correct gait with two crutches, progressive weight bearing as tolerated
- •Active-assisted flexion up to 90°, ankle mobility
Restrictions and precautions
- •Do not force flexion beyond 90° in this phase
- •Avoid prolonged standing and direct skin contact with ice
- •Keep the wound dry for 15-20 days
Criteria to progress
- ☐Passive extension 0°, passive flexion 90°
- ☐Mild to moderate effusion in the anterior/medial compartment
- ☐Ability to hold the knee extended against gravity (no extension lag)
Note for the physiotherapist
Early full extension is the single strongest predictor of good functional outcome: regain it now, not later. Quadriceps control (quad set without lag) precedes any loading progression.
Phase 2 — Strength and neuromuscular control
Weeks 2-12
Goals
- •Regain single-leg balance
- •Restore thigh and posterior chain strength
- •Restore full range of motion
What to do
- •Straight leg raise in 4 directions, hamstring stretching, patellar mobilisations
- •Closed kinetic chain: isometric mini-squat, protected-range leg press, progression bilateral squat → goblet → split squat → lunge → step down → single leg squat
- •Leg curl for hamstrings, calf strengthening, ankle mobility work
- •Proprioception (wobble board, unstable surfaces), slow cycling with high saddle, walking in water
Restrictions and precautions
- •Progress only if the knee stays dry and pain-free over the following 24 hours
- •Caution with open kinetic chain in the 0-30° arc in the early weeks
Criteria to progress
- ☐Passive extension 0°, passive flexion 125°+
- ☐No effusion
- ☐Stable single-leg balance and single leg squat without dynamic valgus
- ☐Thigh circumference >75% of the healthy side
Note for the physiotherapist
Dynamic valgus (femoral internal rotation, knee adduction, ankle eversion) is a re-injury risk factor: assess it with 2D video during single leg squat and drop vertical jump and correct it before adding plyometric load.
Phase 3 — Running, agility and jumping
Months 3-6
Goals
- •Excellent jump, landing and rebound control
- •Agility programme and cardiovascular reconditioning
- •Full recovery of leg and core strength
What to do
- •Slow straight-line running, then figure-of-8 with progressively tighter radius
- •Guided, progressive plyometrics: pool → trampoline → sand → grass → hard surface
- •Agility and deceleration drills with focus on landing technique
- •Continued gym strengthening and neuromuscular work
Restrictions and precautions
- •No contact, no pivoting in uncontrolled situations
- •Pay attention to surface type and footwear
Criteria to progress
- ☐Single hop test >90% of the contralateral side
- ☐Confidence and correct technique on landing
- ☐Strength and thigh girth recovery >90%
Note for the physiotherapist
The keyword is technique: quality of deceleration and landing before volume and intensity. Isokinetic testing at the end of this phase documents the residual deficit.
Phase 4 — Return to team and sport
From month 6-9
Goals
- •Stable, solid knee with excellent neuromuscular control
- •Confident athlete ready to return
- •Recovery of sport-specific technical skills
What to do
- •Individualised programme supervised by a coach or physiotherapist experienced in injury recovery
- •Progressive simulation of sport-specific gestures (shooting, serving, ball skills)
- •Partial team training, then full training before match play
- •Isokinetic test before the outpatient review (around 6-7 months), brought to the appointment
Restrictions and precautions
- •No competitive match play before the full test battery is passed and 9 months have elapsed
Criteria to progress
- ☐Isokinetic muscle deficit no greater than 10% versus the healthy side
- ☐4 hop test battery with LSI ≥90%
- ☐IKDC ≥90 and ACL-RSI >90% (psychological readiness)
- ☐Full team training without symptoms
Note for the physiotherapist
Clearance is multifactorial: clinical assessment + scores (IKDC, ACL-RSI, Melbourne ACL RTS score) + functional tests. A low ACL-RSI predicts failure to return and re-injury even when strength has recovered.
Phase 5 — Re-injury prevention
Ongoing, at least a 6-week structured programme
Goals
- •Improve neuromuscular control in running, sprinting, cutting and jumping
- •Maintain balance between muscle groups
- •Make the programme part of the training routine
What to do
- •FIFA 11+ programme (adult or kids version) built into the team warm-up
- •Balance, endurance and strength work several times a week
- •Education of athlete, coach and strength coach
Criteria to progress
- ☐Prevention programme performed consistently at least 2-3 times a week
- ☐No dynamic valgus at periodic checks
- ☐Strength symmetry maintained over time
Note for the physiotherapist
About 75% of ACL injuries occur without direct contact and a substantial proportion is preventable. Growing athletes and female athletes carry a clearly higher risk for the same activity.
Return to sport / full activity
Pivoting and contact sport: not before 9 months post-op, typically 9-12 months.
- ☐4 hop test battery (single, triple, crossover, 6 m timed) with LSI ≥90%
- ☐Isokinetic quadriceps and hamstring strength with LSI ≥90% (deficit ≤10%)
- ☐Subjective IKDC ≥90
- ☐ACL-RSI >90%: psychological readiness to return
- ☐No effusion, full and symmetrical ROM
- ☐Full team training without symptoms for at least 2-4 weeks
Each month of delay up to month 9 progressively reduces re-injury risk. In patients under 20-25 years the risk of graft or contralateral rupture remains high: continuing the prevention programme after return is an integral part of the protocol.
Red flags: stop and contact us
- •Effusion that returns or increases after sessions: a sign of overload, reduce load and reassess
- •Loss of full extension or new extension lag
- •Joint locking or painful catching (suspected associated meniscal tear or cyclops lesion)
- •Persistent and worsening anterior knee pain
- •Subjective giving way or instability
- •Fever, redness, warmth or wound discharge (suspected infection: contact us immediately)
- •Calf pain with asymmetric swelling (suspected deep vein thrombosis: urgent assessment)
Guidelines and literature
- Grindem H et al. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction (Delaware-Oslo cohort). Br J Sports Med 2016.
- Ardern CL et al. 2016 Consensus statement on return to sport (Bern). Br J Sports Med 2016.
- van Melick N et al. Evidence-based clinical practice update: ACL rehabilitation (Dutch guideline). Br J Sports Med 2016.
- Webster KE, Feller JA. Melbourne ACL Return to Sport Score.
- Wiggins AJ et al. Risk of secondary injury in younger athletes after ACL reconstruction. Am J Sports Med 2016.
Key exercises, step by step
Each exercise belongs to a specific phase: do not anticipate them. Dosage is indicative and must be adapted by your physiotherapist.
1. Quadriceps isometric contraction (quad set)
From day 1
- •Lie on your back with the leg straight and a rolled towel under the ankle.
- •Push the knee down by tightening the thigh, as if flattening the bed.
- •The heel lifts slightly: that means you are reaching full extension.
Dosage: 10 contractions of 5 seconds, 4-6 times a day
2. Straight-leg raise
From day 1-2
- •Lying on your back, first tighten the thigh until the knee locks straight.
- •Lift the straight leg about 30 cm, hold 3 seconds and lower slowly.
- •If the knee bends while lifting, the quadriceps is not ready yet: go back to quad sets.
Dosage: 3 sets of 10, twice a day
3. Vastus medialis activation
Weeks 1-6
- •Sitting with a pillow under the slightly bent knee.
- •Extend the knee by pushing the heel forward, keeping the thigh on the pillow.
- •Focus on the teardrop muscle above the inner side of the knee.
Dosage: 3 sets of 12, once or twice a day
4. Mini-squat 0-45°
From the full weight-bearing phase
- •Standing, feet hip-width apart, weight evenly distributed.
- •Bend the knees to about 45°, keeping the knees aligned over the feet.
- •Rise by pushing through the heels, without letting the knee collapse inwards.
Dosage: 3 sets of 12, 3-4 times a week
5. Glute bridge
From week 2
- •Lie on your back, knees bent, feet flat on the floor.
- •Lift the pelvis by squeezing the glutes until shoulders, hip and knee are aligned.
- •Lower slowly without arching the back.
Dosage: 3 sets of 12-15, on alternate days
6. Controlled step-down
Strength phase (from month 3)
- •Stand on a 15-20 cm step on the operated leg.
- •Lower slowly with the other foot, touching the floor with the heel, over 3 seconds.
- •The standing knee must stay aligned over the foot: if it collapses inwards, lower the step.
Dosage: 3 sets of 8-10 per side, 3 times a week
7. Single-leg balance
From the full weight-bearing phase
- •Stand on one leg, knee slightly bent, looking ahead.
- •Progress: eyes open → eyes closed → soft surface → catching a ball.
- •The pelvis must stay level: if it drops on one side, the gluteus medius is weak.
Dosage: 3 x 30 seconds per side, daily
8. Progressive plyometrics
Impact phase
- •Start with two-foot hops on the spot, landing softly with bent knees.
- •Progress to front-back and lateral hops, then single-leg.
- •Landings must be silent: noise means insufficient shock absorption.
Dosage: 2-3 sets of 10-20 contacts, 2-3 times a week
9. Agility and change of direction
Pre-return-to-sport phase
- •Shuttle runs, figure-of-8, cone slaloms: wide turns first, then sharper cuts.
- •Add unanticipated (cued) direction changes only at the end.
- •No drill should be performed with pain or a feeling of an unsafe knee.
Dosage: 2 sessions a week, within training
10. Low-impact conditioning
All intermediate phases
- •Stationary bike with high saddle and minimal resistance, swimming (avoiding breaststroke early), elliptical.
- •These maintain general fitness without compressing the repaired area.
- •The rule is always the same: no swelling the next day.
Dosage: 20-30 minutes, 3-5 times a week
Frequent questions
Why wait 9 months if I already feel fine at 5?
Subjective feeling improves long before the biological strength of the graft, which keeps remodelling for months. In the Delaware-Oslo cohort re-injury risk fell progressively for each month of delay up to nine, and those who met return-to-sport criteria had roughly an 84% risk reduction.
Do I need a brace?
Not routinely: the literature shows no benefit of rigid bracing after isolated ACL reconstruction. It is prescribed in selected cases, for example with associated lesions or fixation requiring protection.
When can I drive?
Usually between 30 and 45 days, once ROM is adequate, crutches are no longer needed and braking reaction time is normal. Times are usually longer for the right leg than for the left with an automatic gearbox.
Is swelling in the evening normal?
Mild evening swelling in the first weeks is common. It becomes a warning sign when it increases day by day, appears after every session, or does not settle within 24-48 hours with ice and elevation: in that case the weekly load is excessive and should be reduced by one level.
Can I do physiotherapy only once a week?
The physiotherapy session is for setting up, correcting and progressing the programme. The result, however, depends on the exercises performed at home every day: a short daily home programme is worth more than an isolated weekly session.
Anterior Cruciate Ligament (ACL) Reconstruction — Dott. Daniele Priano, Pediatric Orthopaedics · ortopediaevolutiva.com/en/rehabilitation/acl-reconstruction · Information document: it does not replace an in-person assessment.
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Email: daniele.priano@ortopediaevolutiva.com