ACL Rehabilitation & Physical Therapy

Evidence-based rehabilitation protocols, phase-by-phase exercises, and criteria for progressing through your ACL recovery journey.

The Phases of ACL Rehabilitation

Phase 1 Weeks 0-2

Protection & Early Motion

Goals: Protect graft, control pain/swelling, achieve full extension, reactivate quadriceps.

Key exercises: Quad sets, ankle pumps, heel slides, passive extension, straight leg raises.

Detailed Phase 1 Guide →

Phase 2 Weeks 2-6

Early Strengthening

Goals: Full ROM, normalize gait, improve quad strength, wean from assistive devices.

Key exercises: Mini squats, step-ups, stationary bike, balance exercises.

Detailed Phase 2 Guide →

Phase 3 Weeks 6-12

Progressive Strengthening

Goals: Build strength, improve balance and proprioception, cardiovascular fitness.

Key exercises: Leg press, lunges, Romanian deadlifts, single-leg balance.

Detailed Phase 3 Guide →

Phase 4 Months 3-6

Running & Early Plyometrics

Goals: Return to running, introduce jumping, sport-specific movement prep.

Key exercises: Walk-jog progression, two-leg plyometrics, agility ladder.

Detailed Phase 4 Guide →

Phase 5 Months 6-9

Advanced Training

Goals: Advanced agility, cutting/pivoting, sport-specific skills.

Key exercises: Single-leg plyometrics, cutting drills, sport-specific agility.

Detailed Phase 5 Guide →

Phase 6 Months 9-12+

Return to Sport

Goals: Meet return-to-sport criteria, graduated return, prevention program.

Key activities: Return-to-sport testing, practice participation, game return.

Detailed Phase 6 Guide →

Key ACL Rehabilitation Exercises

Quad Strengthening (Critical!)

Quad Sets

Tighten quad, press knee down. 10 reps × 10 sets/day

Details →

Straight Leg Raises

Lock knee, lift leg 6-12 inches. 3×15

Details →

Terminal Knee Extension

Resistance band for final 30° extension

Leg Press

Closed chain strengthening (after week 6)

Hamstring Strengthening

Hamstring Curls

Prone or seated machine curls

Romanian Deadlifts

Hip hinge pattern, hamstring emphasis

Nordic Hamstring Curls

Eccentric strengthening (advanced)

Bridges

Double and single-leg progressions

Balance & Proprioception

Single Leg Stance

Progress: eyes closed, unstable surface

BOSU Balance

Single leg on unstable surface

Perturbation Training

React to external pushes/pulls

View Complete Exercise Library →

Running & Plyometrics Progression

Running Progression (12-16+ weeks)

Criteria to begin:

  • Full, pain-free ROM
  • No swelling
  • Quad strength >70% of other leg
  • Normal gait without limp
  • PT/surgeon clearance

Progression:

  1. Walk 5 min / jog 1 min intervals
  2. Gradually increase jog intervals
  3. Continuous easy jogging
  4. Introduce tempo changes
  5. Add direction changes (curves)

Detailed Running Protocol →

Plyometrics Progression (4-6+ months)

Criteria to begin:

  • Full ROM, minimal swelling
  • Strength >80% of other leg
  • Successful running program
  • Good single-leg balance

Progression:

  1. Two-leg box jumps (low height)
  2. Two-leg hops, bounds
  3. Single-leg hops (forward)
  4. Lateral hops and bounds
  5. Reactive/sport-specific plyos

Plyometric Exercises →

Physical Therapy: How Often?

Phase PT Visits/Week Home Exercise
Weeks 1-6 2-3x Daily (1-2 hours)
Weeks 6-12 2x Daily (1-2 hours)
Months 3-6 1-2x 4-5x/week
Months 6-9 1x or biweekly 3-4x/week + sport
Months 9+ Monthly or as needed Maintenance + sport

PT vs. Home Exercise

Your PT visits are for:

  • Manual therapy and hands-on treatment
  • Exercise progression decisions
  • Form correction and technique
  • Assessment and milestone checking

The majority of your rehab happens at home. Doing exercises only during PT visits is not enough for optimal recovery.

Return to Sport Criteria

Meeting objective criteria before returning to sport reduces re-injury risk.

Category Test/Measure Target
Time Months post-surgery ≥9 months (some say 12)
Strength Quad Limb Symmetry Index ≥90%
Strength Hamstring Limb Symmetry Index ≥90%
Functional Single Hop for Distance ≥90% symmetry
Functional Triple Hop for Distance ≥90% symmetry
Functional Crossover Hop for Distance ≥90% symmetry
Functional 6-meter Timed Hop ≥90% symmetry
Psychological ACL-RSI Score ≥65 (ideally >80)
Clinical ROM, swelling, stability Normal

The 9-Month Rule

Research shows that for each month of delay in returning to sport up to 9 months, re-injury risk decreases by approximately 51%. Returning before 9 months significantly increases re-tear risk. However, time alone isn't sufficient—you must also meet strength and functional criteria. Some research suggests waiting until 12 months may be even safer for high-risk sports.

Return-to-Sport Checklist Tool →

Frequently Asked Questions

Can I do ACL rehab at home? +

Yes, much of ACL rehab can be done at home, but supervised physical therapy is strongly recommended, especially in the first 3-6 months. Home exercises are essential—you should exercise daily at home between PT visits. However, PT provides manual therapy, progression guidance, form correction, and access to equipment that's difficult to replicate at home. A hybrid approach (PT visits + home exercise) is ideal. If access is limited, telehealth PT and detailed protocols can help.

How do I know if I'm doing too much in rehab? +

Signs you're overdoing it: increased swelling after exercise (that doesn't resolve with ice/rest), pain lasting more than 24 hours post-exercise, regression in ROM or function, excessive fatigue, and sleep disruption due to pain. "No pain, no gain" does NOT apply to ACL rehab. Listen to your body and communicate with your PT. Some muscle soreness is normal; joint pain and swelling are warning signs.

What's more important: quad or hamstring strength? +

Both are critically important, but quad strength is often the limiting factor in ACL recovery. The quad is inhibited after surgery (arthrogenic muscle inhibition) and takes active effort to restore. Hamstrings are important because they protect the ACL by preventing anterior tibial translation. A balanced quad:hamstring ratio (ideally 60:40 or better) is optimal. Focus heavily on quad exercises throughout recovery while maintaining hamstring strength.

When can I start cutting and pivoting? +

Cutting and pivoting typically begin around 6-9 months, after meeting criteria: full ROM, minimal swelling, strength LSI >85%, successful plyometric progression, and PT/surgeon clearance. Progression: start with planned, slow cuts, then increase speed, then add reactive/unplanned cuts. This is the highest-risk activity for re-tear, so don't rush. Proper cutting mechanics (avoid knee valgus) are essential.

Ready to Track Your Progress?

Use our assessment tools to measure your rehabilitation progress and readiness for return to sport.