Chiswick-Physio BLOG


Phases of ACL rehabilitation
Knee, ACL
Sports Physio

Explanation of ACL injury and its prevalence

The anterior cruciate ligament (ACL) is one of the 4 main ligaments that stabilise the knee joint and limits hyperextension of the knee. ACL injuries occur most frequently in sports involving pivoting and sudden deceleration on one leg such as football, basketball, gymnastics and skiing, to name a few. Although they can occur in isolation, more frequently they occur along with damage to other structures in the knee such as the meniscus, joint surface or medial collateral ligament. The annual incidence of ACL tears is 81 per 100,000 inhabitants aged 10-64 years.

Importance of ACL rehabilitation in the recovery process

ACL rehabilitation is a fundamental component in the recovery journey post-injury or surgery. It is paramount for reinstating strength, stability, and functionality to the knee. A focused rehabilitation regimen targets muscle strengthening, preventing atrophy, and enhancing overall stability, crucial for restoring normal movement patterns and reducing the risk of future injuries. Beyond the physical aspects, rehabilitation significantly impacts psychological well-being. Attaining milestones in the process positively influences confidence and mental resilience. This comprehensive approach not only minimises re-injury risks but also ensures a secure and successful return to daily activities, prioritising both the physical and psychological aspects of ACL recovery.

Read ACL rehab excercises >

Pre-operative Rehabilitation

Goals and objectives of pre-operative rehabilitation

While the desire for immediate surgery is understandable, allowing the knee to settle and regain strength before the operation is crucial.

The risk of developing a stiff knee after surgery can be significantly reduced if the surgery is delayed until swelling has subsided, a normal or near normal range of motion (especially knee extension) has been obtained, and a normal walking pattern has been reestablished. After an ACL injury, regardless of whether surgery will take place or not, The three most important goals of the Pre-op Phase are;

  • Eliminate swelling
  • Regain full range of motion
  • Regain 90% strength in the quads and hamstring compared with the other side

Exercises and activities during this phase

In this stage, common activities involve consistent knee icing for swelling reduction, mobility exercises, and low-impact aerobic workouts like cycling. A gradual strengthening program is implemented, aligning with the knee’s clinical progress. As pain and swelling subside, and motion improves, strength exercises can advance to include weight training and activities like hopping drills. Caution is advised to avoid aggressive changes in direction during this phase.

Importance of rehabilitation in improving surgical outcomes

The highest incidence of knee stiffness occurs if ACL surgery is performed when the knee is swollen, painful and has limited range of movement. Research has suggested that people who attain full range of motion, good quadriceps and hamstring strength, and minimal swelling prior to surgery have better outcomes than those who don’t up to 2 years post-surgery.

In some instances, ACL surgery may be performed months or years after the original injury. In these cases, if knee range of motion is symmetrical the focus needs to be on strength and proprioception. However, it is very important to give to the injured knee submaximal loads to avoid knee swelling or re-injuring caused by lack of proprioception.

Read: Surgical vs Non-Operative Rehabilitation >

Phase 1: Recovery stage

Overview of the immediate postoperative period

ACL reconstruction surgery is traumatic to the knee, necessitating a dedicated period of rest and recovery post-operation. While the urge to enhance strength and range of motion is understandable, it is advisable to allow the knee to settle during the initial 1-2 weeks. Basic range exercises, quadriceps setting drills, ice, and compression are recommended during this crucial recovery phase. 

Goals and objectives of early post-operative rehabilitation 

In the initial phase following ACL reconstructive surgery, key objectives focus on promoting effective recovery and laying the groundwork for subsequent rehabilitation stages. The three primary goals during Phase 1 are:

  • Get the knee straight (full extension)
  • Settle the swelling down to ‘mild’
  • Get the quadriceps firing again

Education on postoperative care, compliance with rehabilitation protocols, and a cautious approach toward activity progression underscore this critical recovery phase.

Exercises and strengthening activities during phase 1

The postoperative phase following ACL reconstruction (ACLR) involves a progressive and structured rehabilitation program. Common exercises and strengthening activities include:

  • Isometric Quadriceps contraction
  • Straight Leg Raises
  • Heel Slides
  • Mini Squats
  • Stationary Bike
  • Calf Raises
  • Hamstring Curls
  • Balance and Proprioception Exercises
  • Wall Slides
  • Lunges
  • Step-Ups

The specific exercises and their intensity may vary based on the individual’s progress, surgeon’s recommendations, and the overall rehabilitation plan.

Modalities and pain management techniques used in this phase

Common management practices during this phase involve regular application of ice to the knee and graft donor site (typically the hamstrings, quad, or patella tendon). At Chiswick-Physio, we recommend opting for a Cryo Cuff or considering rental of a Game Ready system instead of traditional ice packs. The use of analgesics and medications may be necessary and should be guided by your doctor. In certain situations, electrical stimulation of the quadriceps muscle might be employed through a TENS or Compex unit. Knee stability, as per the surgeon’s protocol, may involve the temporary use of a knee brace, with the goal of removing it within the initial 2-4 weeks.

Phase 2: Strength and neuromuscular control 

Transition from initial to intermediate rehabilitation phase 

Phase 2 aims to restore muscle strength, balance, and fundamental coordination. Moving from the simple body weight exercises in phase 1, phase 2 evolves into a gym-based routine encompassing resistance, balance, and coordination exercises. It’s crucial for clinicians and patients to ‘listen to the knee’ and only progress as quickly as the knee will allow. The two main symptoms that indicate that the knee is not tolerating the workload are an increase in swelling and pain. 

Goals and objectives of intermediate post-operative rehabilitation

A key focus is regaining muscle strength, particularly in the quadriceps, hamstrings, and calf muscles. The rehabilitation plan will evolve into a gym-based regimen, introducing resistance training to fortify muscles and enhance overall functionality. 

Proprioception is honed to refine the sense of knee position and movement while pain and swelling are vigilantly managed. Functional and sport-specific training may be incorporated, gradually reintroducing impact activities. Patient education remains integral, emphasising adherence, proper technique, and self-monitoring to instill confidence in the knee’s stability.

The three most important goals of Phase 2 are:

  • Regain most of your single leg balance
  • Regain most of your muscle strength
  • Single leg squat with good technique and alignment

Introduction of more challenging exercises for strength and stability

Typical exercises during this phase include: 

  • Lunges, 
  • Step-ups
  • Squats 
  • Bridging 
  • Calf raises 
  • Hip abduction strengthening
  • Core exercises
  • Balance
  • Gait re-education drills
  • Non-impact aerobic conditioning such as cycling, swimming, and walking. 

Some clinicians may start some introductory impact type activities such as walk-jogging or mini jumps during this phase, but the bulk of this type of training should be reserved for Phase 3.

Proprioceptive training and balance exercises

In Phase 2 of post-operative rehabilitation after ACL reconstruction, proprioceptive and balance exercises are crucial. These may include single-leg stance, balance exercises on unstable surfaces, and proprioceptive drills. These exercises enhance joint position sense, stability, and coordination, reducing the risk of re-injury and improving overall functional performance during daily activities and sports. By challenging the neuromuscular system, you will develop better control over limb movement, fostering confidence and preparing them for more advanced activities in later phases of rehabilitation.

Phase 3: Running agility and landing

Progression to Late Post-operative Rehabilitation

In Phase 3 of the ACL rehabilitation protocol, there will be a reintroduction of running, agility drills, jumping, and hopping. Concurrently, a gym-based program for strength and neuromuscular development continues. This stage allows for the initiation and gradual advancement of change-of-direction training and modified game play. While engaging in these activities, supervision by the clinician is advisable to ensure proper guidance and monitoring of the athlete’s progress.

Goals and objectives of phase 3

In this stage, the knee should be free from swelling and pain, with a specific focus on correct technique, especially during deceleration tasks like landing from a jump. Prior to advancing to full sports participation in Phase 4, it is important to perfect landing and pivoting biomechanics.

The three most important goals of Phase 3 are:

  • Achieve hopping proficiency (technique, distances, & endurance)
  • Successfully progress through an agility program and modified game play
  • Regain symmetrical and full strength of the lower limb

Exercises to get from running to sport specific

Activities in Phase 3 comprise agility drills like slalom running, shuttle runs, and ladder drills. Jumping and hopping exercises commence with scissor jumps and single hops, advancing to box jumps and single-leg landings with perturbations. Given the emphasis on eccentric muscle activity, incorporating rest and recovery periods is crucial during this phase to optimize the effectiveness of exercises and activities.

Phase 4: Return to sport 

Progression to the final phase of ACL rehabilitation

Individualising Phase 4 ACL rehabilitation is crucial, incorporating typical exercises and training activities involved in your desired sport. Focus should not only be on getting the knee ready for sport, but the whole person, both physically and mentally. The knee needs to be stable and strong, with optimal neuromuscular patterning and biomechanics. But mental preparedness is also essential for the athlete’s confidence.

Goals and objectives of late post-operative rehabilitation

Phase 4 should prioritise the seamless integration of your chosen sports activities into routine training. Rehabilitation should emphasise familiar exercises and activities, not solely focusing on knee readiness but considering the strength and conditioning of the entire body. Confidence building through repetitive successful training and sport-specific drills is key. Regular monitoring, risk mitigation, and mental preparedness contribute to a gradual, monitored return to full activity.

Functional training and sport-specific exercises

During this stage, incorporating functional training and sport-specific exercises is essential. Examples include agility drills, plyometrics, cutting and pivoting exercises, and drills mimicking specific movements in the athlete’s sport. Additionally, progressive strength training with an emphasis on power and endurance contributes to overall functional capacity. The goal is to optimise performance by addressing sport-specific demands, enhancing neuromuscular coordination, and preparing you for the dynamic challenges inherent in your chosen activity or sport.

Return to play criteria and considerations

In this phase, it’s crucial to establish a foundation through strength, balance, landing, and agility exercises. However, the primary focus of Phase 4 ACL rehabilitation is the systematic progression from constrained to unrestricted training. This ultimately culminates in a return to competition once you are fully prepared.


Recap of the different phases of ACL rehabilitation

At Chiswick-Physio the ACL rehab protocol is broken down into a number of phases, each stage requiring objective measurements to be reached before starting the next phase of rehabilitation. In summary: 

  • Pre-op rehab focuses on strength and mobility, transitioning to surgery if needed.
  • Phase 1 prioritises swelling and pain management.
  • Phase 2 concentrates on muscle strengthening and range of motion. 
  • Phase 3 introduces agility and jumping exercises, emphasising technique. 
  • Phase 4, uses a personalised approach integrating sport-specific training, gradually advancing to a return to full competition. 

Throughout, careful monitoring, rest, and mental preparedness contribute to a comprehensive rehabilitation journey tailored to your individual needs.

Importance of following a structured rehabilitation program

Following a structured rehabilitation program is crucial for optimal recovery and outcomes after an injury or surgery. At Chiswick-Physio we recommend you should move through the ACL protocol at your own pace, and let the criteria govern how quickly you go, not a predetermined timeline.

Encouragement for individuals going through ACL rehabilitation

Embarking on ACL rehabilitation is undoubtedly challenging, but every step forward is a triumph. You will have good days and bad days, the main aim is to keep the line of improvement on a gradual inclined slope. Here are a few tips on how to progress through an ACL rehab protocol with minimal problems: 

  • Get the knee straight early (within the first 2-3 weeks both post injury and post surgery), and keep it straight. Flexion can progress gradually.
  • Use knee pain and knee swelling as a guide. If either or both are increasing, the knee isn’t tolerating what you’re doing to it.
  • Technique is everything. Compensation patterns develop after an ACL tear, so focusing on correct muscle and movement/biomechanical patterns is paramount.
  • Build high impact forces gradually. The articular structures in the knee joint will take time to adapt to a resumption of running, jumping and landing.
  • Complete your ACL rehabilitation. Once people are back running with no knee pain it’s easy to think that it’s all done. But the last 1/3 of the protocol is the most important – to help reduce the chance of re-injury and increase the chance of a successful return to sport.

Trust the structured program, your dedicated clinicians, and most importantly, your own resilience. Your journey is unique, but with determination and commitment, you’ll conquer each phase, emerging stronger and more resilient than ever. 

Frequently asked questions ACL rehab phases

Why is ACL rehab so long?

The extended duration of ACL rehab is primarily attributed to the necessity of gradual strengthening of muscles and ensuring the successful integration of the graft. Achieving muscle strength and graft stability involves a carefully phased approach, incorporating progressive overload to avoid complications and support a robust recovery.

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What is a realistic ACL recovery time?

Many underestimate the commitment required for a full recovery post-surgical ACL repair, with the process spanning 9 to 18 months. Chiswick-Physio advocates for a minimum of 12 months of rehabilitation before returning to sport. Returning before the 9-month mark entails a 50% higher risk of reinjury, underscoring the importance of a comprehensive and patient approach to ensure a successful recovery.

Can you speed up ACL rehab?

While adherence to a structured rehabilitation program is crucial, attempting to expedite ACL rehab is risky. Rushing the process may compromise outcomes and increase the risk of reinjury. Rather than fixing to a specific timeline of moving through the phases of rehab certain outcome measures related back to function, strength, proprioception and stability must be reached before you move on to the next phase of rehabilitation. 

Can you walk too much after ACL surgery?

In the early stages of ACL surgery recovery, walking is typically encouraged, but it’s crucial to balance activity with rest. Following a progressive increase in load and walking, as guided by your healthcare team, is essential. Walking too much, especially without proper progression, can lead to increased swelling and stress on healing tissues.

Will I ever be 100% after ACL surgery?

Achieving 100% recovery after ACL surgery is a realistic goal for many individuals, but it’s important to note that the extent of recovery can vary. Success depends on factors such as adherence to rehabilitation, individual response to treatment, and the presence of any pre-existing conditions. While many people return to their pre-injury levels of activity and sport, some may experience mild limitations. Patience, commitment to rehabilitation, and following healthcare guidance enhance the chances of reaching optimal recovery.

How long after ACL surgery does it take to be able to walk normally?

Generally, after surgery, you will be walking with assistance, such as crutches or a brace. As healing progresses, a gradual transition to normal walking usually occurs within a few weeks to a couple of months.

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