Knee injury ACL

ACL Rehabilitation

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Anterior cruciate ligament (ACL) injuries are common among athletes and require a thorough rehabilitation program to ensure optimal knee function and prevent further injury. The Melbourne Return to Sports protocol is a criteria-driven ACL rehabilitation protocol that guides both clinicians and patients who have undergone surgical reconstruction of the ACL (1). The protocol is broken down into six phases, and the goals of each stage should be achieved before progression to the next stage (1). 

The six phases are:

  • Pre-op Phase: Injury recovery & readiness for surgery
  • Phase 1: Recovery from surgery
  • Phase 2: Strength & neuromuscular control
  • Phase 3: Running, agility, and landings
  • Phase 4: Return to sport
  • Phase 5: Prevention of re-injury
Woman Massaging man's knee | knee injury with the expert

Pre-op Phase: Injury recovery & readiness for ACL surgery

There is considerable evidence to demonstrate that rehabilitation before surgery is beneficial to recovery. ACL reconstruction should be performed once the knee has recovered from the acute injury, has a full range of motion, and is pain-free to optimise the outcome and avoid complications such as knee stiffness. The goals of this phase include:

  • Reducing swelling and inflammation
  • Restoring full range of motion (fully straight or full extension is especially important)
  • Regaining strength in the quadriceps, hamstrings, and calf muscles
  • Improving balance and proprioception
  • Regaining the ability to hop and land

Exercises and activities during this phase typically include regular icing of the knee to reduce swelling, range of motion exercises, low impact aerobic exercise such as cycling, and a progressive strengthening regime. As your swelling decreases and your strength is improving, you may also start doing weighted exercises in the gym as well as jumping and landing drills. Aggressive change of direction activities should probably be avoided during this phase, unless you are looking at conservative management.

A machine is being tried on a patient with a muscle concern.

Phase 1: Recovery from ACL surgery

ACL reconstruction surgery is traumatic to the knee and a period of rest and recovery is required after the operation. Typically, 1-2 weeks of easy quad activation exercises and gentle range of motion is appropriate. Depending what procedures are performed during your surgery, your surgeon may have specific post operative instructions. For example, after a meniscal repair there is often a period of non-weight bearing. You will need to practice walking with crutches and there may even be limits on how much bending you can do with your knee.

The primary goal immediately after surgery is to get the knee straight as soon as possible, and have the quadriceps muscles starting to fire again.

Important goals in this acute recovery phase include:

  • Reducing swelling and inflammation
  • Restoring full extension (knee straightening)
  • Regaining strength in the quadriceps and reducing quads inhibition.
  • Improving balance and proprioception

Typical exercises and management activities during this phase include regular icing of the knee and graft donor site (usually either the hamstrings, quad or patella tendon), compression of the knee and lower limb, basic quadriceps setting exercises, and gentle range of motion exercises to improve knee extension (straightening) and flexion (bending). Analgesics and other medications should only be used in consultation with your doctor.

A man lifting weights with the assistance of an exercise physiotherapists in Brisbane.

Phase 2: Strength & neuromuscular control

This phase usually commences with easy body weight type exercises and progresses into a
gym-based regime with a mixture of resistance, balance, and co-ordination exercises. During this stage it is easy to do too much too soon. It’s important that clinicians and patients to ‘listen to the knee’ during this phase and only progress as quickly as the knee will allow. Monitoring for any increase in pain and/or swelling is important as these are the two main symptoms that indicate that the knee is not tolerating the workload. Its important to adjust your program based on how your knee is feeling. It is important that by the end of this phase your knee is no longer swelling in response to exercise.

The focus of this phase is to improve neuromuscular control and coordination of the lower limb. The goals of this phase include:

  • Regaining full range of motion (both bending and straightening)
  • Regaining most of your leg strength (all muscles in the legs)
  • Improving balance and proprioception
  • Single leg squat with good technique and alignment

Typical exercises and management activities during this phase include lunges, step-ups, squats, bridging, calf raises, hip abduction strengthening, core exercises, balance, gait re-education drills, and non-impact aerobic condition such as cycling, swimming, and walking.
It is strongly recommended that in this stage you will need to complete your rehab program in a gym. This program can be prescribed by your Physiotherapist, Exercise Physiologist or Strength and Conditioning coach. If you are wanting to return to sport after your ACL surgery, you will need to be lifting heavy weights to improve your strength sufficiently. As a reference point, your goal in this stage is to single leg press 1.5x your body weight for one rep, and squat 1.5x your body weight.

If you are progressing well with your rehab you may be able to start some introductory impact type activities such as walk-jogging or mini jumps during this phase. However, the bulk of this type of training should be reserved for the next phase.

Agility training following ACL injury

Phase 3: Running, agility, and landings

Phase 3 of this ACL rehabilitation protocol sees a return to running, agility, jumping and hopping, as well as the continuation of a gym based strength and neuromuscular program. It’s important that there is some rest and recovery time during this phase as many of the exercises and activities are much more intense.

The goals of this phase are to:

  • Improve running, agility, jumping, and hopping ability
  • Improve strength and endurance of the whole body
  • Improve technique for deceleration tasks such as landing from a jump
  • Develop movement skills in change of direction tasks and agility

The knee should be swelling and pain free during this phase, and an emphasis is placed on correct technique particularly for deceleration tasks such as landing from a jump. It’s important to perfect landing and pivoting biomechanics before progressing fully back to sport (Phase 4). Change of direction training and modified training can also commence and progress during the later stages of this phase, although supervision and individualised exercise prescription is strongly recommended.
Exercises and activities in Phase 3 typically include agility drills such as slalom running, shuttle runs, and ladder drills. Jumping and hopping exercises usually start with drills such as scissor jumps and single hops and progress to box jumps and single leg landings with perturbations. It is important to think about preparing for your sport or activity and plan your rehab. This is where our team of experts with experience in elite sport can really help your rehab along and help you return to sport safely. A footballer needs different rehabilitation and conditioning to a basketball player or netball player, and your rehabilitation should be individualised for you.

2 man playing football

Phase 4: Return to sport

This phase of ACL rehab should be highly individualised, and moving toward performing exercises and training activities that you would be doing if you were not injured. By now your knee is likely feeling strong and by progressing through your previous phase you are feeling agile, moving well and think you are ready for sport. However, there is still a lot of mental and physical challenge that needs to be recreated in a sporting context to ensure you are prepared (contact, decision making etc). Return to sport needs to be graded and progressive.

Focus should not only be on getting the knee ready for sport, but the whole person. The knee needs to be stable and strong, with optimal neuromuscular patterning and biomechanics. But the athlete needs to be confident and mentally ready to return to sport, and this will come from repetition of successful training and match play situations.

A background of strength, balance, landing, and agility work needs to be continued during this phase (and continue on into Phase 5), but the emphasis of Phase 4 ACL rehab is on progressive training, from restricted to unrestricted training. This can be done by manipulating drills and training requirements (smaller areas, less traffic, slower pace, longer rest etc).

At this stage, we also assess your psychological readiness and confidence to return to sport. This is just as important as the physical testing to make sure you feel equipped and capable of returning to sport.

Phase 5: Prevention of re-injury

Once you have returned to your sport and activity it is important to remain engaged with an injury prevention program. Injury prevention exercises can be incorporated into your warm up as well as into your ongoing gym program.

ACL injury prevention programs aim to improve the neuromuscular control of individuals during standing, cutting, and landing tasks. These are the movements that are high risk for ACL injury

Key components of an injury prevention program should include:

  • Plyometric, balance, and strengthening exercises
  • That the program must be performed for at least 10mins before every training session and game
  • That the program is on going and you can be consistent

There are existing sport specific protocols our there if you would like some guidance.

Five popular injury prevention programs that include exercises to help reduce ACL injuries are
available on the internet.

It is important to note that the Melbourne Return to Sports protocol is a criteria-based approach to ACL rehabilitation, ensuring that athletes are truly ready to return to sport after ACL reconstruction. The advantage of this approach is that it recognises that different people progress at different rates for a variety of reasons (3). Rehabilitation of patients with an ACL rupture should be led by a team including a Sports Physiotherapist as well as an Exercise Physiologist or Strength and Conditioning coach (4). Our team is highly experienced in rehabilitation of patients with ACL rupture. 

The ACL rehab protocol should be completed at the patient’s own pace, and the criteria should govern how quickly they progress, not a predetermined timeline1. Once people are back running with no knee pain, it’s easy to think that it’s all done. But the last phases of the protocol are the most important – to help reduce the chance of re-injury, increase the chance of a successful return to sport, and possibly to reduce the likelihood of osteoarthritis down the track (1).


(1) The Melbourne ACL Rehabilitation Guide 2.0

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