The anterior cruciate ligament (ACL) is a strong band of fibrous tissue within the knee joint that connects the thigh bone (femur) to the shin bone (tibia). Combined with the posterior cruciate ligament (PCL), the ACL and PCL form an “X” within the knee joint to provide stability to the forward (ACL) and backward (PCL) movements of the knee as well as rotational stability (ACL and PCL combined).

ACL injuries typically occur with rapid stopping and or starting; quick changes in direction and/or cutting (such as seen in soccer); landing from a jump with the knees straight or hyperextended; being tackled while standing (football); or as a result of a bad fall (skiing).  Most ACL injuries ( >70%) are non contact in nature.

The incidence of tears to the anterior cruciate ligament (ACL) in pediatric athletes is unfortunately increasing. A study from the University of Minnesota found that ACL tears have increased 2.3% per year over the last 20 years alone!  This may be due to the increasing participation rates and increased volume of activity young athletes engage in. Said differently, more kids are playing more, resulting in more injury.

Females are at higher risk of ACL tears compared to males.  In pediatric populations, most happen around the age of 16 for girls and 17 for boys. Some factors that explain why females are at greater risk for ACL injury include:

• Wider hips which add increased force to the knee when changing direction quickly as in a soccer game.
• Decreased muscular mass to support the knee compared to their male counterparts.
• Greater joint and ligamentous laxity compared to men secondary to genetics and possibly hormones.

ACL Injury Symptoms

Symptoms of an acute ACL injury typically include:

1. A sensation of tearing or popping within the knee joint. Sometimes an audible pop is heard.
2. The inability to immediately weight bear or continue to play sport.
3. Swelling and/or bruising that develop within 24 hours.
4. Difficulty fully straightening the knee due to hamstring spasm.

Symptoms of a chronic ACL injury (ACL insufficiency) include:

1. A feeling on instability within the knee joint.
2. Increased stress or strain on the back of your knee/hamstrings as they tighten to keep the knee from hyperextending.
3. A feeling like the knee may give out.
4. A lack of confidence in your ability to play sports, cut, pivot etc..
5. Difficulty balancing on the affected leg.
6. Periodic episodes of swelling and pain.

My child has torn their ACL, do they need surgery?

When your child experiences a traumatic knee injury, navigating the health care system and determining what the best options are can be very daunting.  In order to determine if your child is a candidate for surgery, a clinical exam conducted by a physiotherapist or sports medicine physician or orthopedic surgeon, coupled with an X-Ray to rule in/out fracture and MRI to assess the integrity of the ligaments and meniscus is a good starting point.  The physical therapists at REP Physio are happy to triage your and your child at this stage and direct them to the appropriate professional and/or imaging as quickly as possible.

Surgery is typically considered if:

1. The ACL is completely torn.
2. There is other trauma to the knee (torn meniscus, or MCL injury or tear)
3. There is severe functional instability that affects activities of daily living.
4. The injured athlete wants to return to a sport that includes contact, pivoting cutting etc..

If you choose to have surgery, the timing of surgery can be important. A systematic review and meta-analysis conducted by James et al. in 2021 found that:

“Delaying ACL reconstruction in pediatric or adolescent patients for >12 weeks significantly increased the risk of meniscal injuries and irreparable meniscal tears; however, early and delayed operative treatment achieved satisfactory knee stability. Nonoperative management resulted in high rates of residual knee instability, increased risk of meniscal tears, and comparatively low rates of return to sports.”¹  

Many individuals do choose the non-surgical route and can have a high degree of function. Ideally, they can expect to have minimal pain in the long term, and should be able to perform recreational activities without much concern (running in a straight line, riding a bike etc.). However, activities that demand jumping, cutting, pivoting or contact sports, may prove to be challenging. To prevent against this, a persistent rehabilitation program should be followed for upwards of 2 years post ACL rupture, as many with an ACL injury still demonstrate functional weakness of one or both legs at the 2 year mark.

ACL rehabilitation exercise principles to maximize recovery. 

First and foremost, if you think you have injured your ACL, or are recovering from ACL knee surgery, it is important that you consult with your surgeon and/or trusted health care team, such as the experienced physiotherapists at REP Physio in Edmonton as you begin your rehab journey.

The use of this information in the blog post should not replace the advice of a professional that is familiar with your unique situation.  The reality is that there is not one gold standard or set of exercises to strengthen your affected leg. However, there are some key principles worth following to maximize your recovery:

1. First, your progress through the various phases of your recovery need to be based on your function (key milestones), your symptoms, in addition to days on the calendar.  You may progress quickly through some phases of your recovery, while others may take longer. They key is to be patient.
2. There is no one “best test” (for example the Hop Test) or clear functional evaluation guideline to determine your appropriateness for to return to sport.³  Rather, a multitude of factors need to be considered, including patient preferences, psychological readiness to return to sport, time since injury, strength, range of motion, ability to be active with minimal pain etc.
3. Post-surgical ACL return to play criteria need to also consider graft maturity, which can take 6-12 months.  Many guidelines for return to sport recommend waiting 9-12 months.
4. As noted above, many athletes that return to sport following ACL surgery still demonstrate considerable muscular deficits and imbalances on the affected limb upwards of 2 years post-surgery.  The incidence of re-injury following an ACL repair is as high as 29%. Again, be careful and patient, and be persistent with your rehab plan.

An example of early stage non-surgical and post-surgery ACL rehabilitation exercises:

Again, as noted above the information in this blog should not replace the advice of a health professional familiar with your unique situation.  Additionally, there are no gold standard, “one size fits all” “best exercises” ACL rehabilitation guidelines. Rather certain practitioners or centers may provide you with their own “in-house” protocol. The exercises listed below are designed to provide a general overview of typical stages following an ACL injury. At REP Physio in Edmonton, we always tailor exercises to your specific needs, circumstances and goals.

Early/Acute Stage

Early on, a key part of recovery focuses on minimizing pain and swelling.

•  Early Stage Exercises After ACL Injury (surgical):
  • Typical exercise in the immediate aftermath of surgery include pumping your ankles, and gentle range of motion exercises of your knee to minimize stiffness. Swelling and post-surgical pain can limit your function in this stage. Generally speaking the goal early on is to achieve full range of motion into extension (fully straightening the knee).  Flexion can take longer given the increased swelling within the knee.
  • Ensure your home is better prepared for a rehab program and recovery. Remove tripping hazards, set up your home if possible to minimize the use of stairs. Have grab bars in the bathroom if needed. Get extra pillows for sleeping to place under your knee.
  • You’ll likely require crutches for ambulation as it can be difficult to bear weight. If you are tackling stairs, go up with the “good” leg first, and down with the bad.  Take the stairs one at a time.
  • You may require medications for pain management. Ask your doctor about how to best manage pain flare ups.
  • Pump your calf muscles throughout the day to help with swelling.
  • It may be very painful to bend your knee, so don’t force anything.
  • Post-surgery acl rehabilitation exercises in the initial stage are typically limited as your body recovers from the surgery itself.
•  Early Stage Exercises After ACL Injury (non-surgical)
  • You may need to use crutches if it helps you walk.
  • Exercises are advisable. Begin knee motion soon after injury as tolerated.
  • You may need to lie on your back and perform heel raises by contracting your quads and hip flexors.
  • You may be asked to bend and straighten your knee throughout the day
  • Knee and ankl.e motion should begin as soon as comfortable.
  • Minimize pain and swelling by keeping the knee elevated when possible.
  • Attempt to achieve terminal knee extension (full straightening/the back of the knee flat against the surface of the floor).
  • Pump your calf muscles.
  • You may be able to do a stationary bike as tolerated
  • You may be doing exercises for the hip such as banded hip abductions to help provide further stability of the knee and pelvis.
  • Rember to focus on correct form for all exercises. If unsure ask your physical therapist, trainer, or sports med physician.

After the acute stage the focus shifts to restoring range of motion and working on normalizing gait.

Sub-Acute Stage Exercises After ACL Injury (surgical)

• Following surgery, the focus at this stage continues to be achieving full knee straightening while minimizing pain and swelling. To this end, you may be asked to place a small towel under the back of your knee and contract your quadricep by pushing your knee flat against the towel
• 2+ weeks after surgery, and with approval from your surgeon, you may be able to do the recumbent bike to improve range of motion of the knee.  However you may find bending the knee difficult due to swelling (90 degrees to 110 degrees of knee flexion is a good goal to shoot for here, as it will make stairs, the recumbent bike and getting in and out of vehicles easier). However, remember to be patient, don’t force it.
• Try to achieve a normal walking cycle.
• Assume normal activities of daily living as tolerated.
• Continue to minimize pain and swelling

Sub-Acute Stage Exercises After ACL Injury (non-surgical)

• Focus on normalizing gait.
• If you are able to walk normally and load the affected limb without pain or compensation with activities of daily living, you can focus on muscle strength and knee motion with the following exercises: squats, bridges, side lying or standing hip abduction with an exercise band, shallow standing knee extension against resistance etc.. Your partner or health care aide may need to help you with exercises in this stage (hold the band, help getting off and on the bike etc.).
• ACL exercises at this stage can also include some single leg strength exercises to strengthen muscles that stabilize the hip.
• Again, at REP Physio, we want you to tailor exercises to your specific injury and needs. To this end, we may incorporate elements of your specific sport into your rehab journey as tolerated

Exercises following the early stages of ACL injury vary depending on the protocol, the pediatric athlete’s goals, their pain, function and swelling.  It is important to keep in mind that non-surgical rehab can take weeks to months, whereas post-surgical rehab can be ongoing for 6-24 months depending on the individual.

Throughout your recovery, you can expect to receive exercises that provide targeted strengthening of the quadriceps and hamstrings, claves, hips and core. These can include, but are not limited to:  quats, lunges, hamstring curls, knee bend exercises, seated knee extension, straight leg raises, calf and or heel raises These exercises are designed  to hep stabilize the knee, as well as working on strengthening the hip musculature to help control the pelvis while allowing for optimal loading patterns through the knee with dynamic movements.  Your program should eventually include sports specific exercises as needed.  The intensity of the exercises should be dictated by your form and pain, and your rehabilitation program should above all, be very active.  While passive approaches may feel nice at the time, they will not improve your strength and function long-term.

What Can I Do To Minimize The Risk of ACL Injury For My Child?

Here are a few key tips to help minimize the risk of ACL injury:

1. Ensure your child is getting adequate rest.
2. Pay attention to how your child moves and behaves outside of sport.  Sometimes children can be reluctant to tell their parents or their coaches that they are hurt. Look for changes in their behaviour, mood, and movement patterns.
3. Be mindful of how much activity our child is doing on a weekly basis.  A general guideline is that your child should be active no more hours than their year in age per week. For example, a 9 year old should only be playing soccer for 9 hours per week or less.
4. Activity induced soreness should be gone soon after the activity has ceased. If activity related pain lasts greater than 24 hours, they are likely doing too much. While you don’t have to necessarily stop, consider doing less.
5. Consider speaking with coaches and trainers about complimenting their on-field practice and games with strength and balance training.
6. Consider incorporating elements of the FIFA 11+ injury prevention program into your child’s training.  This program, which can be done in as little as 20 minutes, has been shown to decrease the knee injury risk in soccer players (which have a high incidence of knee and acl injury) aged 13+ of both genders by 30%.⁴

ACL exercises are key to recovery

Whether your ACL injury is surgical or non-surgical, a persistent physical therapy led exercise program is crucial to guide you through each acl rehabilitation phase.  Mobility, balance, strength, stability, psychological readiness and acknowledgement of tissue healing timelines all need to be considered when retuning to your pre-injury activity.  It is important for you to stay committed, be patient and surround yourself with the right team of professionals to maximize your results.

References:

1. James et. al. “Early Operative Versus Delayed Operative Versus Nonoperative
   Treatment of Pediatric and Adolescent Anterior Cruciate Ligament Injuries.” American Journal of Sports Medicine. 2021.
2. R. Queen “Infographic: ACL injury reconstruction and recovery” Bone Joint Research 2017
3. American Academy of Orthopaedic Surgeons Clinical Practice Guideline Summary: “Management of Anterior Cruciate Ligament Injuries” Journal of the American Academy of Orthopaedic Surgeons 31 (11) p 531-537 June 2023 
4. Sadigurski et. al. “The FIFA 11+ injury prevention program for soccer players: a systematic review.” BMC Sports Science, Medicine and Rehabilitation (2017) 9:18