ACL Rehabilitation: A Complete Guide to Recovery and Strengthening

Recovering from an anterior cruciate ligament (ACL) injury requires a structured approach to regain strength, stability, and function in your knee. Whether you have undergone surgery or are preparing for one, rehabilitation exercises are crucial to restore mobility, prevent reinjury, and gradually return to daily activities and sports.

ACL injuries not only affect the stability of the knee but can also impact your overall leg alignment and posture. Early rehabilitation focuses on activating the surrounding muscles, including the quadriceps and hamstrings, to support knee function and prevent compensatory movement patterns that could lead to further injury.

This guide provides a step-by-step roadmap, combining at-home exercises, advanced phase exercises, and functional training.

Understanding ACL Injuries

The ACL is a critical ligament in the knee that stabilizes and supports leg movement. ACL injuries often occur due to overstretching, sudden stops, or twists during physical activity. Severe tears may require surgery, followed by a structured rehabilitation program to regain full function.

Key challenges after an ACL injury include:

• Knee instability

• Loss of quadriceps and hamstring strength

• Restricted range of motion

• Reduced confidence in knee function

At-Home Rehabilitation: Early Phase

The early phase of ACL rehab focuses on regaining gentle movement and strengthening the muscles around the knee particularly the quadriceps (front thigh) and hamstrings (back thigh) without putting excessive weight on the injured knee.

1. Heel Slides
   Sit on the floor with legs extended.
   Slide the heel of your injured leg toward your body, bending the knee.
   Slowly return to starting position.
   Repeat 10 times, 1–4 times daily.
   

2. Isometric Quad Contractions
   Sit with your injured leg extended.
   Tighten your quadriceps without moving the knee.
   Hold for 10 seconds, relax, repeat 10 times.
   

3. Prone Knee Flexion
   Lie on your stomach with legs straight.
   Bend the injured knee, bringing your heel toward your buttocks.
   Hold for 5 seconds, relax, repeat 10 times.
   

Strengthening these muscles helps maintain proper posture and balance during daily movements. This ensures that while the knee heals, other joints like the hip and ankle are not overloaded, supporting a smoother recovery and preventing stiffness in the leg.

1. Prone Hip Extension
   Lie on your stomach with the knee straight.
   Lift the injured leg slightly off the ground by squeezing your glutes.
   Perform 10 repetitions, repeat once more.
   

2. Sitting Towel Calf Stretch
   Sit with legs extended.
   Place a towel around the foot of the injured leg and gently pull toward you.
   Hold for 30 seconds, repeat 3 times.

3. Ankle Pumps
   Lie on your back.
   Flex and point your toes on the injured side.
   Repeat 10 times, twice daily.

Tip: Avoid exercises that cause pain. Mild discomfort is normal, but sharp pain signals that you should stop and consult your physical therapist.

Intermediate Phase: Strengthening After Swelling Subsides

Once swelling decreases and you can stand on both legs without favoring the injured knee, you can progress to exercises that gradually build strength and stability.

1. Passive Knee Extensions
   Sit between two chairs, placing your heel on one chair.
   Relax and let your knee straighten for 1–2 minutes. Repeat several times daily.
   

2. Heel Raises
   Stand holding a chair for balance.
   Lift heels slowly onto toes, hold for 5–10 seconds, lower slowly.
   Repeat 10 times.
   

3. Half Squats
   Hold a sturdy table for support.
   Bend knees slightly to a half squat, hold 10 seconds, then rise.
   Repeat 10 times.
   

4. Knee Flexion with Resistance Band
   Anchor a band to a stable object and loop it around the injured ankle.
   Bend your knee against resistance, hold a few seconds, slowly return.
   Repeat 10 times.

As you progress, it’s important to focus not just on knee strength but also on coordinated movement. Performing exercises with proper alignment helps reinforce good posture, optimizes load distribution across the leg, and prepares the knee for functional activities like walking stairs, stepping, and light lunges.

1. Single-Leg Standing
   Balance on the injured leg for 10 seconds, gradually increasing duration as strength improves.
   

2. Partial Lunges
   Step forward slightly with the injured leg, bend knee slightly, keeping back leg straight.
   Avoid pain and maintain proper form. Repeat 10 times.
   

“Watch this video where Opus Physio explains how different activities, such as biking and playing sports, place varying levels of stress on the knee. In the video, we discuss how sports involving quick changes in direction or jumping often create higher stress on the ACL, increasing the risk of injury, while biking applies more controlled, repetitive motion that allows for safer knee movement during recovery.”[https://www.youtube.com/watch?v=Ko_IlZDAZBw]

Advanced Phase (Phase 3): Preparing for Sports and Full Function

Phase 3 is designed to regain pre-injury functionality, including agility, endurance, and power. This phase typically begins 7–10 weeks post-surgery, depending on individual progress.

Goals of Phase 3:

• Full range of motion, equal to the non-injured leg

• Strength reaching 70–75% of the uninjured leg

• Single-leg balance and motor control improvement

• Introduction of plyometrics and sports-specific activities
  

During advanced rehab, attention to posture and movement mechanics becomes crucial. Exercises are designed to restore knee strength while improving balance, coordination, and functional mobility. This reduces the risk of re-injury and ensures that the leg works efficiently during sports or high-demand activities.

Key Exercises in Phase 3

1. Seated Passive-Assisted Knee Extension
   Use your non-operative leg to gently lift the injured leg straight while seated.
   Repeat 10–20 times, 2–3 times daily.
   

2. Standing Hip Flexion with Resistance
   Attach a band to a secure object, loop it around your ankle.
   Lift the leg forward slowly, keeping the knee straight.
   Perform 12 repetitions, 1–3 times daily.
   

3. Single-Leg Hip Extension and Abduction
   Step back or to the side with a resistance band.
   Lift leg slowly, maintaining balance and control.
   12 repetitions per leg, 1–3 times daily.
   

4. Double-Leg Quarter Squats
   Feet shoulder-width apart, bend knees ~60 degrees, keep weight evenly distributed.
   Return to standing slowly, repeat 12 times.
   

5. Single-Leg and Double-Leg Heel Raises
   Strengthen calves for walking, jumping, and running.
   Perform 12 repetitions, 1–2 times daily.
   

6. Step-Ups
   Step onto a stable platform, lifting the opposite knee to 90 degrees.
   Step down slowly, repeat 12 times per leg.
   

7. Standing Hip Hinge
   Balance on one leg, hinge forward at hips with straight back leg.
   Repeat 12 times per leg, optionally holding a small weight.
   

8. Anterior Reach
   Stand straight, bend one knee while reaching the opposite foot forward.
   Lightly touch the heel, return to standing, repeat 12 times.

Self-Assessment and Confidence

Recovery is not just physical. Monitoring function and confidence is vital:

• Compare current knee function to pre-injury level (1–10 scale).

• Evaluate confidence in the reconstructed ACL using tools like the ACL-RSI questionnaire.

• Use honest self-assessment to guide further rehabilitation and avoid re-injury.

Remember, ACL rehabilitation not only rebuilds knee strength but also reinforces proper posture, alignment, and functional leg movement. A well-rounded approach supports safe return to activity and long-term joint health.

Recovery Milestones

By the end of Phase 3:

• Daily activities like walking, stair climbing, and getting in/out of a car should be comfortable.

• Quad strength should reach 70–75% of the non-injured leg.

• Single-leg balance and plyometric exercises should be possible without pain or swelling.

Next Steps: For those aiming to return to sports, supervised rehab should continue, including running, jumping, pivoting, and sport-specific drills.

Key Tips for Successful ACL Rehab

• Consistency is critical – skipping exercises can delay recovery.

• Listen to your body – mild discomfort is okay, sharp pain is not.

• Work with a professional – guidance from a physical therapist ensures proper form and progression.

• Track progress – celebrate milestones to stay motivated.

• Balance strength and mobility – both are essential for preventing re-injury.
  

Conclusion

ACL rehabilitation is a phased, structured journey designed to restore strength, stability, and confidence. From gentle at-home exercises to advanced plyometric training, a well-planned program ensures a safe and effective recovery. Remember, progress may vary, so always follow the guidance of your healthcare professional to achieve optimal results.

Choosing the Right Therapist: The Key to ACL Rehab Success

Watch this video where Opus Physio explains how selecting the right physiotherapist can make a significant difference in your ACL rehabilitation journey. The right guidance ensures proper technique, progression, and ultimately, a safer and more effective recovery. https://youtu.be/tVV8feZXSEE