ACL Reconstruction Rehabilitation Guide

Understanding Your ACL Reconstruction

The anterior cruciate ligament (ACL) is the cornerstone of knee stability. It prevents your shin bone from sliding forward on your thigh bone and provides rotational control during pivoting, cutting, and landing activities. When this ligament tears, the knee becomes unstable—especially during sports that involve sudden direction changes.

ACL reconstruction replaces your torn ligament with a graft. This graft could be your own patellar tendon, hamstring tendons, or quadriceps tendon (autograft), or donor tissue (allograft). The graft serves as a scaffold for new ligament formation. Over months, this graft transforms into living ligament tissue through a process called "ligamentization."

Think of your new ACL like a rope bridge being rebuilt. First, the scaffolding goes in (surgery). Then the structure weakens as it remodels (weeks 2-12). Gradually, new collagen fibers organize and strengthen (months 3-6). Finally, the bridge regains full capacity (months 6-9). Rushing this process risks collapse. Patience and protection are your allies.

Recovery Timeline Overview

ACL rehabilitation follows a carefully sequenced progression that mirrors the biological healing of your graft:

Week 0-2: Protection Phase

The goals are simple but critical: protect the graft, manage pain, and establish early motion.

Daily Milestones

Essential Exercises (Weeks 0-2)

Quadriceps Sets:

• Lie or sit with surgical leg extended
• Push knee down into surface, tightening thigh muscle
• Focus on the quad contraction, not the knee movement
• Hold 5-10 seconds, relax completely
• 3 sets of 10-15 reps, 3-4 times daily

Straight Leg Raises:

• Lie on back, surgical leg straight, non-surgical knee bent
• Tighten quad, lift surgical leg 12 inches off surface
• Keep knee straight throughout—don't let it bend
• Hold 3-5 seconds at top, lower slowly
• 3 sets of 10 reps, 3-4 times daily

Heel Slides (for flexion):

• Lie on back, slide heel toward buttock
• Bend knee as far as comfortable
• Return to full extension (use gravity help)
• Use plastic bag under heel for easier sliding
• 3 sets of 10-15 reps, 3 times daily

Prone Hangs (for extension):

• Lie on stomach with thighs supported on bed/table
• Let surgical leg hang freely over edge
• Gravity helps knee fully extend
• Start with 1-2 minutes, progress to 5-10 minutes
• Perform 3-4 times daily
• This is the most effective extension exercise

Patellar Mobilizations:

• Sit with surgical leg extended
• Gently push patella up, down, medial, lateral
• Move it in all directions
• If it feels stuck, hold gentle pressure for 30 seconds
• 5-10 minutes, 3 times daily

Week 2-6: Motion Phase

This phase emphasizes restoring full range of motion, normalizing gait, and beginning proprioception training.

Motion Progression

Key Exercises (Weeks 2-6)

Wall Slides for flexion:

• Lie on back near wall with feet on wall, knees bent
• Let gravity help knees bend toward floor
• Slide feet down wall to increase stretch
• Hold at maximum stretch for 30 seconds
• 2 sets of 10-15 reps, 2 times daily
• Progress by lowering feet further down wall

Stationary Bike for motion and cardio:

• Start with seat HIGH to reduce knee bend
• Initially: no resistance, just motion
• Aim for 10-15 minutes, progress to 20-30 minutes
• Excellent for promoting knee flexion
• Use as warm-up before other exercises
• Avoid resistance until full ROM achieved (usually week 4-6)

Single Leg Balance for proprioception:

• Stand near wall or counter for safety
• Balance on surgical leg, start with 10-15 seconds
• Progress to 30+ seconds as able
• Proprioception (joint position sense) is disrupted by ACL injury
• Balance exercises retrain nerves that tell your brain where your knee is in space
• This is crucial for preventing re-injury
• 2 sets of 5 reps, hold each as long as able, 2 times daily

Mini Squats for function:

• Stand holding counter for support
• Squat slightly, bending knees 20-30 degrees
• Keep weight evenly on both feet
• Avoid going past 60 degrees (protects graft)
• 2 sets of 10-15 reps, 2 times daily
• Progress depth as quad strength improves

Step Ups for confidence:

• Use 4-inch step with handrail
• Step up with surgical leg, bring non-surgical up
• Step down with non-surgical first, then surgical
• Focus on controlled movement, not speed
• 2 sets of 10 reps, 2 times daily
• Progress to standard step height as strength improves

Week 6-12: Strengthening Phase (Critical Graft Protection)

This is the danger zone—your graft is weakest as it remodels. Strengthening must be balanced with protection.

Month 3-6: Functional Phase

Now that graft is strengthening, focus shifts to functional movements and sport preparation.

Running Progression

Running Progression Program

Week 1-2: Straight-ahead jogging

• Warm-up: 5-10 minutes bike
• Walk 1 minute, jog 1 minute × 5
• Focus on smooth gait pattern
• Stop if pain or swelling increases
• Cool down with ice and elevation

Week 3-4: Continuous jogging

• Jog 2-3 minutes, walk 1 minute × 5
• Progress to continuous jogging 10-15 minutes
• Maintain even pace on flat surface
• Monitor for swelling (should be minimal next morning)

Week 5-6: Speed and distance

• Jog 20-30 minutes continuously
• Begin gentle pace variations
• Still no cutting or pivoting
• Progress based on symptom response

Agility Progression (Month 5+)

Only after cleared for straight-ahead running:

Week 1: Linear movements

• Forward/backward running
• Side shuffling (no planting/pivoting)
• Cariooca (grapevine) drill

Week 2-3: Direction changes

• Figure-8 runs (large, gradual curves)
• 45° cuts (gentle, controlled)
• Zigzag cones (wide spacing)

Week 4+: Sport movements

• 90° cuts
• Sharp direction changes
• Stop-and-go drills
• Sport-specific patterns

Plyometrics Progression

Plyometrics (jump training) prepares knee for sport demands:

Level 1 (Month 4-5): Landing mechanics

• Step off 6-inch box, land softly
• Focus on knee alignment (don't let knee collapse inward)
• 2 sets of 10 reps

Level 2 (Month 5-6): Vertical jumps

• Small vertical jumps, land softly
• Progress height gradually
• 2 sets of 8-10 reps

Level 3 (Month 6+): Horizontal and lateral

• Broad jumps
• Lateral jumps
• 180° jumps

Level 4 (Month 7+): Sport-specific

• Single-leg hops
• Box jumps
• Depth jumps

Month 6-9+: Return to Sport Phase

This is the final phase—preparing for full return to sport.

Return-to-Sport Testing Battery

Limb Symmetry Index (LSI) Tests: Compare surgical to non-surgical leg

Single Leg Hop for Distance:

• Hop forward on one leg, measure distance
• Surgical leg should achieve ≥90% of non-surgical
• 3 trials, best distance recorded

Triple Hop for Distance:

• Three consecutive hops on one leg
• Measure total distance
• Surgical ≥90% of non-surgical

Crossover Hop:

• Three hops while crossing midline
• Measures multiplanar stability
• Surgical ≥90% of non-surgical

Timed Hop:

• Hop 6-meter distance for time
• Surgical ≥90% of non-surgical

Isokinetic Strength Testing:

• Quad strength at 60°/second and 180°/second
• Hamstring:quad ratio important
• Surgical quad ≥90% of non-surgical

Warning Signs: When to Seek Help

Re-injury Prevention

The highest risk period for re-injury is the first year after return to sport.

Graft Type Considerations

Different grafts have different rehabilitation considerations:

Patellar Tendon Graft (Bone-Patellar Tendon-Bone):

• Strongest graft initially
• Bone-to-bone healing in tunnels (fastest incorporation)
• Risk of anterior knee pain ( kneeling discomfort)
• Risk of patellar fracture (rare)
• Rehabilitation can be slightly more aggressive initially
• More anterior knee pain, especially with kneeling

Hamstring Tendon Graft:

• Softer graft initially, weaker early fixation
• Takes longer to incorporate (soft tissue to bone)
• Less anterior knee pain
• Risk of hamstring weakness
• More cautious progression initially
• Better cosmetic result (smaller incision)

Quadriceps Tendon Graft:

• Similar to patellar tendon but without patellar fracture risk
• Large graft, strong fixation
• Less anterior knee pain than patellar tendon
• Growing in popularity
• Rehabilitation similar to patellar tendon

Allograft (Donor Tissue):

• No donor site morbidity (less pain initially)
• Slower incorporation (your body must integrate donor tissue)
• Higher failure rate in young athletes
• Often used for revision surgeries or older patients
• More cautious rehabilitation progression

Common Questions

References