ACL Reconstruction – 8 Key Points in Rehabilitation

 

Anterior Cruciate Ligament (ACL) injuries in professional and non-professional athletes can cause a long lay-off from sports and may even be career-ending, or at the very least, threaten the progression of one’s career (1). ACL injuries typically occur via non-contact mechanisms and require significant intensive rehabilitation prior to resumption of athletics. Decelerating, cutting, and rotational moments especially during landing, are the most common mechanisms for ACL rupture.

Perhaps the most widely considered risk factor is dynamic knee valgus, which places significant tensile forces on the ACL especially during landing and cutting. Knee valgus may occur secondary to many factors, including but not limited to weak hip abductor strength, poor hip musculature control, increased femoral anteversion/medial tibial torsion, increased Q-angle or increased midfoot mobility.

Other potential risk factors that have been theorized for ACL injury include poor postural control and more upright landings. Poor postural control may result in the inability to appropriately respond to perturbations, which increases the stabilizing requirement of the ACL during movements and play. (2) These are among the many factors that should be considered during rehabilitation.

Most of the time, complete ACL tears require surgical repair, especially for athletes who perform pivot and rotational movements in their sport. Post-surgical outcomes depend on many factors as mentioned before, so clinicians should be accurate and efficient on assessment, rehabilitation and return to sport (RTS) programming. 

In this article, I will cover 8 key points to follow in rehabilitation from injury to return to sport. 

 

(1) Be optimally prepared for surgery – Prehabilitation works! 

Professional athletes are usually blessed with the opportunity to be operated immediately following injury (within 3-5 days). However, non-professional athletes might wait 4-6 weeks before undergoing surgery due to delayed access to surgery and/or personal reasons. Rehabilitation can begin in advance of the surgery, with the aim of reducing the swelling and regaining range of motion and strength.  Current literature confirms that appropriate prehabilitation programs result in superior knee function and strength post-surgery.

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(2) Consider the type of surgery – Simple to complex

Several different surgical techniques can be performed for ACL repair (ACLR) which can be linked either to the surgeon and to the severity of injury. You could be dealing with a reconstructed ACL using different types of grafts (patellar, gracilis, semitendinosus, quadriceps tendons, artificial ligaments); isolated ACLR; ACLR plus meniscectomy or meniscus suture. It is imperative to be aware of and understand the surgical technique when you begin rehabilitation, so communicating with the surgeon and getting details is imperative whenever possible. Furthermore, keep in mind the biological healing process and joints mechanics when you choose the exercises like Open Kinetic Chain (OKC) or Closed Kinetic Chain (CKC) exercises – right exercise, right time, right joints.  

For example, if your athletes underwent gracilis/semitendinosus grafts, hamstring exercises should be avoided initially, focusing primarily on the knee extensors; with an athlete who underwent patellar tendon ACLR, leg extension exercises should be avoided in early stages. However, ACLR performed with an artificial ligament allows to start leg extension exercises in the early stages.

 

(3) Reduce pain and swelling, then address gait

Immediately after surgery, the main goals are to reduce pain and swelling with any technique which works according to your clinical experience. Literature shows that cryotherapy or Neuromuscular Electrical Stimulation (NMES) combined with exercise is effective in the early rehab stages in order to reduce pain and activate inhibited muscles. At the same time, focusing on gait is important given the effect of post-surgical limitations in weight bearing.  Work on knee flexion and extension range of motion, full ankle range of motion, foot mechanics and gait pattern. 

 

(4) Rebuild StrengthRehab is training!

Movement dysfunction can be driven from muscle imbalances that are a result of muscle inhibition, synergistic dominance of specific muscle group or relative strength deficits (weakness, but normal function). The distinction between the two is vitally important and will directly contribute to the success of a rehab training program. If inhibition is present, then it needs to be treated in order to effectively train a subsequent movement. If a muscle is inhibited, it cannot activate at a sufficient level to contribute to a movement.  As such, it cannot be trained in function and attempts to do this will likely result in compensatory movement. This only perpetuates a cycle of strength imbalance.  Therefore, clinicians and trainers should gradually start with:

1 – Isolated muscle strength aiming to 80% Limb Symmetry Index (LSI). For example: knee extension and knee flexion strength can be tested isometrically on both legs with manual dynamometer, then results can be compared aiming to less than 20% deficit.  Alternatively, isokinetic testing can be performed to assess maximal strength and endurance of the knee extensors or knee flexors for both legs.

2 – Re-training functional movements – bodyweight exercises

3 – Functional strength development – adding load

 

(5) Landing Mechanics and Plyometrics

Prior to initiating landing tasks on the ground, it is also recommended that the athlete have attained at least one times body mass (single limb) and two-times body mass (double limb) for set of eight repetitions on the leg press. 

Bilateral landing allows for the training of eccentric control at the required speed, to prepare for single limb acceptance drills (e.g., single leg landing, running). Variations and progressions include landing from a box, landing from running on the spot or landing from a squat jump:

 

The use of different surfaces can support the reduction in peak landing forces, such as use of the pool, sand or trampolines. (3)

Plyometric training has been reported to be superior to more traditional resistance training for development of explosive lower limb performance and can contribute to improvements in lower limb strength and power, increased joint awareness, and overall proprioception. (3,4) ACL ruptures have been shown to occur within 0.05 seconds after ground contact. (5). For these reasons don’t forget to retrain Rate of Force Development (RFD) which is defined as the ability to produce maximal strength in a short very short time.

Having sufficient RFD is important to be able to utilise the maximal strength in short time during specific movement – Counter Movement Jump (CMJ), Drop Jumps or Single Leg Hop and other related variations/progressions:

 

(6) Deceleration and cutting re-training

Deceleration should be re-trained when your athlete can perform a single leg squat, bipodal landings, and running on treadmill with good results. As mentioned before, deceleration requires good strength and eccentric control, so be aware of volume and technique when your athlete starts practicing it. 

On the other hand, cutting and changing directions represent a challenge for both the clinician/trainer and the athletes. Rotational and anti-rotation exercises are recommended in the early stages in rehabilitation starting from a static position to improve rotational control maintaining pelvis stability on single leg stance:

 

We can then progress to re-training the cut manoeuvre starting from simple and slow exercises with 30°/45° degrees of direction change gradually progressing to 90° degrees cutting at end-stage. All these progressions /regressions can be performed with good control and technique in a gym environment in order to prepare the athlete for On Field Rehabilitation (OFR).

 

(7) On Field Rehabilitation 

Bridge the gap! Don’t let the players return to sport too soon. During OFR, begin practicing high speed and agility drills, unconscious practice, increasing physical conditioning, practicing sport specific skills and increasing training load aiming to the demands of the sport. 

For example, athletes should initially start with linear drills at low speed and progressively move forward to perform multidirectional drills at high intensity. On field rehabilitation is a continuum process to return to sport. (6)

 

(8) Test and Measurements 

In order to fully complete each step, the athlete should be tested and re-tested periodically during rehabilitation. It is vitally important to understand the progression and address the strength deficits or movement quality before moving forward. Studies have shown that respecting RTS stages and tests reduces the risk of re-injury (7). A few tests that can be performed are the isokinetic testing, Hop or Triple-hop test, Movement Analysis Test, T-agility test.  

If you don’t have expensive equipment, it does not matter! Keep it simple: you can test with a leg press 1RM, a Star Excursion Balance Test (SEBT), or even video analysis with Tablet/Smartphone. Choosing the right test linked to the specific sport is essential for monitoring progress and performance.  

For example, if the athlete is filmed performing a single leg squat on the injured leg, movement pattern deficits can be addressed, so the clinician or trainer can break down the movement and correcting it through specific exercises and coaching. 

 

image single-leg squat

Figure 1: Single Leg Squat assessed with Smartphone. Anterior view shows excessive knee valgus and hip adduction, pelvis hike and slight trunk lean.

Rehabilitation should be a multifactorial and interdisciplinary approach. It is essential that each step is undertaken in succession as per a criterion-based progression and that each step be fully completed before progressing to the next step. Failure to do so can result in incomplete or failed rehabilitation (e.g., early reinjury on RTS or even injury during the late-stage rehabilitation process). (6)

 


 

Federico Picchetti, Sports Physiotherapist, CSCS

in collaboration with Mai-Linh Dovan M.SC., CAT(C)

Federico is a Sports Physiotherapist specialized in sports rehabilitation and injury prevention in Italy. For the past 8 years, he has worked in different clinics in Pisa, London and Bologna learning different manual therapy skills, technical skills and rehabilitation methodologies. Since 2020, he has set up his own clinic in Pisa where he treats clients and athletes.

 

References 

1 – Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases. 2015
Markus Waldén, Tron Krosshaug, John Bjørneboe, Thor Einar Andersen, Oliver Faul and Martin Hägglund

2 – Review Stiff Landings, Core Stability, and Dynamic Knee Valgus: A Systematic Review on Documented Anterior Cruciate Ligament Ruptures in Male and Female Athletes. 2021
Joseph Larwa, Conrad Stoy, Ross S. Chafetz, Michael Boniello and Corinna Franklin

3 – A ten task-based progression in rehabilitation after acl reconstruction: from post-surgery to return to play – a clinical commentary. 2020
Matthew Buckthorpe, Antonio Tamisari, Francesco Della Villa

4 – Comparison of land-based and aquatic-based plyometric programmes during 8-week training period. 2002
Miller M, Berry C, Bullard S, Gilders R.

5 – Mechanisms of anterior cruciate ligament injury in basketball: video analysis of 39 cases. 2007

Tron Krosshaug, Atsuo Nakamae, Barry P Boden, Lars Engebretsen, Gerald Smith, James R Slauterbeck, Timothy E Hewett, Roald Bahr

6 – Update on functional recovery process for the injured athlete: return to sport Continuum redefined. 2018

Matthew Buckthorpe, Antonio Frizziero, Giulio Sergio Roi

7 – Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is Associated with a four times greater risk of rupture. 2016

Polyvios Kyritsis, Roald Bahr, Philippe Landreau, Riadh Miladi, Erik Witvrouw

 

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