Anterior Cruciate Ligament (ACL) Rehabilitation

Definition/Description[edit | edit source]

Ligaments of the knee joint superior aspect Primal.png

ACL rehabilitation has undergone considerable changes over the past decade. Intensive research into the biomechanics of the injured and the operated knee have led to a movement away from the techniques of the early 1980's characterized by post operative casting, delayed weight bearing and limitation of ROM, to the current early rehabilitation program with immediate training of ROM and weight bearing exercises.

The major goals of rehabilitation of the ACL-injured knee:

  • Gain good functional stability
  • Repair muscle strength
  • Reach the best possible functional level
  • Decrease the risk for re-injury

Closed kinetic chain exercises (CKC) and Open kinetic chain exercises (OKC) play an important role in regaining muscle (quadriceps, hamstrings) strength and knee stability.

Closed kinetic chain exercises have become more popular than Open kinetic chain exercises in ACL rehabilitation. Clinicians believe that CKC exercises are safer than OKC exercises because they place less strain on the ACL graft. Besides, they also believe that CKC exercises are more functional and equally effective as OKC exercises.

Clinically Relevant Anatomy[edit | edit source]

Please see these pages for relevant anatomy: Anterior Cruciate Ligament (ACL) and Anterior Cruciate Ligament (ACL) - Structure and Biomechanical Properties

General Considerations[edit | edit source]

Acute Stage[edit | edit source]

After ACL injury, regardless of whether surgery will take place or not, physiotherapy management focuses on regaining range of movement, strength, proprioception and stability.

PRICE should be used in order to reduce swelling and pain, to attempt full range of motion and to decrease joint effusion.

Exercises should encourage range of movement, strengthening of the quadriceps and hamstrings, and proprioception. Consider integrating any of these exercises into a rehabilitation programme at this stage as appropriate for the client:

  • Static quads/SLR
  • Ankle DF/PF/circumduction
  • Knee flexion/extension in sitting
  • Patellar mobilisations
  • Glutes medius work in side lying
  • Gluteal exercises in prone
  • Knee flexion in prone (gentle kicking exercises)
  • Weight transfers in standing (forwards/backwards, side/side)

Neuromuscular Electrical Stimulation (NMES) combined with exercise is more effective in improving quadriceps strength than exercise alone[1].

Also consider taping to provide stability and to encourage reduction in swelling.

Before Surgery[edit | edit source]

RICE and electrotherapy can be applied during several weeks ahead of the surgery in order to reduce swelling and pain, to attempt full range of motion and to decrease joint effusion. This will help the patient to regain better motion and strength after the surgery[2]. The patient must be mentally prepared for the surgery. [3]

Before proceeding with surgery, the acutely injured knee should be in a quiescent state with minimal swelling, have a full range of motion and the patient should have a normal or near normal gait pattern. It is important to prepare the knee for surgery as well as possible to optimise the outcome. To assist pre-operative optimisation, the following guidelines are recommended in the acute and sub acute stages post injury:[3]

  1. Immobilize the knee: Use a knee immobilizer and crutches until you regain good muscular control of the leg. Extended use of the knee immobilizer should be limited to avoid quadriceps atrophy.
  2. Control Pain and Swelling: Icing and anti-inflammatory medications are used to help control pain and swelling.
  3. Restore normal range of motion: Quadriceps isometrics exercises, straight leg raises, and range of motion exercises should be started immediately to achieve full range of motion as quickly as possible.
    1. Full extension is obtained by doing the following exercises: Passive knee extension, Heel Props, Prone hang exercise.
    2. Bending (Flexion) is obtained by doing the following exercises: Passive knee bend, Wall slides, Heel slides.
  4. Develop muscle strength: Once 100 degrees of flexion has been achieved you may begin to work on muscular strength. Examples of exercises are: Stationary Bicycle, Swimming, Low impact exercise machines such as an elliptical cross-trainer, leg press machine, leg curl machine, and treadmill can also be used.
  5. Mental preparation: Patient must know what to expect of the surgery and understand the rehabilitation phases after surgery.

Pre-op therapy should encourage strengthening of the quadriceps and hamstrings. Range of motion exercises should be included if there is no pain involved.[4][5] See below for examples of appropriate exercises.

Pre Operation ACL ex.PNG

After Surgery[edit | edit source]

  • Week 1
    • Regular icing and elevation are used to reduce swelling. The goal is full extension and 70 degrees of flexion by the end of the first week. The use of a knee brace and crutches are imperative.
    • Multidirectional mobilizations of the patella should be included for at least 8 weeks. Other mobilization exercises in the first 4 weeks are passive extension of the knee (no hyperextension) and passive and active mobilization towards flexion. Strengthening exercises for the calf muscle, hamstring and quadriceps (vastus medialis) can be performed.
  • Week 3-4
    • The patient must try to genuinely increase the stance phase in an attempt to walk with one crutch. With good hamstring/quadriceps control, the use of crutches can be reduced earlier.
  • Week 5
    • The use of the knee brace is progressively reduced.[2][4]. Passive mobilizations should normalize motility but flexion should not yet be thorough. 9 Tonification of hamstrings and quadriceps (vastus medialis) can start in close chain exercises. The exercises should be started on light intensity (50% of maximum force) and progressively increased to 60-70%. The closed chain exercises should be built from less responsible positions (bike, leg presses, step) to more congested starting positions (ex.squad). The progress of the exercise depends on pain, swelling and quadriceps control. Proprioception and coordination exercises can start if the general strength is good. This includes balance exercises on boards and toll.
  • Week 10
    • Forward, backward and lateral dynamic movements can be included as well as isokinetic exercises[4].
  • Month 3
    • After 3 months, patient can move on to functional exercises as running and jumping. As proprioceptive and coordination exercises become heavier, quicker changes in direction are possible. To stimulate coordination and control through afferent and efferent information processing, exercises should be enhanced by variation in visible input, surface stability (trampoline), speed of exercise performance, complexity of the task, resistance, one or two-legged performance, etc.[4].
  • Month 4-5
    • Final goal is to maximize endurance and strength of the knee stabilizers, optimize neuromuscular control with plyometric exercises and to add the sport-specific exercises. Acceleration and deceleration, variations in running and turning and cutting manoeuvres improve arthrokinetic reflexes to prevent new trauma during competition.[5]

Three factors are important: 1) early terminal knee extension equal to the contralateral side, 2) early weight bearing, and 3) closed and open kinetic chain strengthening exercises. Early knee extension establishes the foundation for the entire rehabilitation program. The incidence of knee flexion contracture with associated quadriceps weakness and extensor mechanism dysfunction following ACL reconstruction has significantly decreased with accelerated knee extension immediately after surgery. Quadriceps strength is enhanced with early extension and weight bearing. The combination of early knee extension, early weight bearing, and closed kinetic quadriceps strengthening allows the patient to progress through the post-operative rehabilitation period at a rather rapid pace without compromising ligamentous stability.[3] Early weight bearing appears beneficial and may decrease patellofemoral pain. Early motion is safe and may help avoid problems with later arthrofibrosis. Continuous passive motion is not warranted to improve rehabilitation outcome in patients and can avoid the increased costs associated with CPM. Minimally supervised physical therapy in selected motivated patients appears safe without significant risk of complications. Postoperative rehabilitative bracing either in extension or with the hinges opened for range of motion does not offer significant advantages over no bracing.[6] The need for postoperative functional bracing and for consensus involving the duration of the bracing in many rehabilitation protocols comes into question. Harilainen et al have compared the effects of functional bracing after ACL reconstruction against not bracing post- operatively. No significant difference in functional outcome, degree of stability, or isokinetic muscle torque was detected at 1 and 2 yrs postoperatively between the two groups. In a similar study, Risberg et al found no significant differences in knee-joint laxity, range of motion, muscle strength, functional knee tests, or pain. [6]

Open versus Closed Kinetic Chain Exercise[edit | edit source]

Closed Chain Exercise

Open-Kinetic-Chain exercises:[edit | edit source]

Characteristics[edit | edit source]
  • Non-weight bearing
  • Movement occurring at a single joint: isolation movements that promote more shearing forces[7]
  • Distal segment free to move
  • Resistance is usually applied to the distal segment
Open-Kinetic-Chain Knee-Extension exercises[edit | edit source]

These exercises have a limited role in ACL rehabilitation programs, because research showed that OKC-extension exercises from 60° to 0° flexion, markedly increase anterior tibial translation in the ACL-deficient knee, as well as ACL graft strain in the reconstructed knee.[2]

Despite these findings, OKC-extension exercises aren’t excluded in ACL-rehabilitation programs, because the same research has shown that OKC-extension exercises from 90° to 60° of flexion could be done safe, without increasing anterior tibial translation or ACL graft strain.[2]

In short, OKC-extension exercises in ACL rehabilitation programs could be done safe in a ROM from 90° to 60° flexion and are furthermore useful to train the quadriceps isolated.

Open-Kinetic-Chain Knee-Flexion exercises[edit | edit source]

OKC-flexion exercises play an important part in the rehabilitation process because research showed that there is no anterior tibial translation or ACL graft strain during these exercises. Besides, they result in isolated hamstrings muscle contraction.[8]

Closed-Kinetic-Chain Knee exercises[edit | edit source]

Characteristics[edit | edit source]
  • Weight bearing
  • Movement at several joints: compound movements that generally incur compressive forces[7]
  • Distal segment fixed to a surface: the extremity remains in constant contact with the immobile surface, usually the ground[9]
  • Resistance may be applied both proximally and distally: the entire limb is loaded[9].
Closed-Kinetic-Chain Knee exercises[edit | edit source]

CKC exercises play an important role in ACL rehabilitation because they result in a hamstrings-quadriceps co-contraction that reduces tibiofemoral shear forces. Besides, research showed that during CKC exercises body weight provides tibiofemoral joint compression, that also reduces tibiofemoral shear forces .[7]

CKC exercises have several advantages compared with OKC exercises

  • Increase stability in the knee joint (more joint compression)
  • Functional load
  • Strong coordinative training
  • Minimal shear force
  • Less stress on the ACL
  • Training of the entire extension chain [10]
  • No selective muscle training
  • Weakest link in the chain is feeling the most "overload" and the corresponding largest trainings effect
  • Fewer complications such as patellofemoral symptoms
  • CKC-exercises are earlier to apply than OKC-exercises

Bynum et al. (1995) concludes that closed kinetic chain exercises are safe, effective, and sacrifice some important advantages over open kinetic chain exercises. [8]

A more recent systematic review[11] of RCTs comparing OKC vs CKC exercises in patients post-ACLR has found that:

  • There is no or insufficient evidence to demonstrate difference between OKC & CKC for pain scores or joint laxity
    • the former could be explained by (1) lack of sensitivity with used questionnaire, (2) statistical power of analysis was insufficient, or (3) there is actually no difference in pain experienced by patients undertaking OKC vs CKC
  • "There is weak evidence that open chain exercises are better for improving knee extensor strength, this is countered by weak evidence for better active knee flexion in closed chain activities."

Examples[edit | edit source]

Postoperative phase 1 ( 1-5 weeks)[edit | edit source]

Exercises 1:

  • The first CKC-exercises are sitting exercises because they facilitate flexion and extension movements in the knee [9].
  • The patient lying on a table has to extend the knee against resistance from a stretcher.

Return to Sport[edit | edit source]

An ACL injury leads to static and functional instability that causes changes in motion patterns and an increased risk of osteoarthrosis. In many cases, an ACL injury results in a premature end to a career in sports. [18]


Strength and power deficits after surgery may be a risk factor for future injuries and may set athletes up for failure when they try to return to their prior performance levels. Researchers suggest that the surgically repaired leg should perform at least 90% as well as the uninjured leg before you return to sport[20]. Three hopping tests can be used as part of a comprehensive physical and functional examination to help ensure not just a speedy, but a safe return to sport after ACL reconstruction. These3 tests are sensitive enough to measure side-to-side differences and can be used during more advanced recovery phases after surgery to help ensure that the athlete’s exercise program is successful in returning the injured leg at least to the level of the uninjured leg[20].

When Should an Athlete Return to Sport After an ACL Surgery?

Other Considerations[edit | edit source]

Suggestions From the Field for Return-to-Sport Rehabilitation Following Anterior Cruciate Ligament Reconstruction: Alpine Skiing[21]

Late stage rehab ideas with specifics for the female athlete

In a retrospective, cross-sectional analysis conducted by Culvenor et al.[22]. 30% of patients had patellofemoral pain (PFP) 12-15 months following ALCR using a hamstring graft. Those who were 27 and older were 2.6 times more likely to report PFP. Patellofemoral cartilage lesions, mensical tears (both assessed by arthroscopy), pre-injury activity level, time from injury to surgery and sex were not predictors of post-operative PFP.

Those who hadPFP did not have reduced range of movement but performed worse at hop distance and single leg tasks. Patients also reported significantly lower quality of life, poor returning sport attitudes and increased kinesiophobia.

PFP is important to consider as maladaptive, fear avoidance patterns of movement perpetuate pain and functional disability by lowering pain experience thresholds. The use of appropriate language during rehab and psychosocial interventions are recommended.

Rehab Protocols[edit | edit source]

Evidence for Open and Closed Chain Exercises[edit | edit source]

In one study there was found no difference in strain on the intact ACL between OKC and CKC exercises. Currently, ACL grafts may respond more like the intact ACL. Therefore they argue, both types of exercise could be done safe[2]. A study that examined the effect of OKC and CKC exercises on functional activity concludes that both open kinetic chain and closed kinetic chain programs lead to an equal long-term good functional outcome[4].In another study, group 1 carried out quadriceps strengthening only with CKC while group 2 trained with CKC plus OKC exercises starting from week 6 after surgery. It seemed that the addition of OKC quadriceps training after ACL reconstruction results in a significantly stronger quadriceps without reducing knee joint stability at 6 months and also leads to a significantly higher number of athletes returning to their previous activity earlier and at the same level as before injury. The authors conclude that the combination of OKC and CKC exercises is more effective than CKC exercises alone[5].

A study that compared the amount of anterior tibial displacement in the ACL-deficient knee during (1) resisted knee extension, an OKC-exercise and (2) the parallel squat, a CKC-exercise, concluded that the ACL-deficient knee had significantly greater anterior tibial displacement during extension from 64° to 10° in the knee extension exercise as compared to the parallel squat exercise[8].There is also a study who concluded that CKC-exercises are safe and effective and offer some important advantages over open kinetic chain exercises.

Bracing[edit | edit source]

While bracing remains controversial[6], this video explains the concepts behind the action of a brace to protect the ACL.


Adjuncts[edit | edit source]

NMES - Neurotech's Kneehab XP Quadriceps Therapy System has been shown to significantly improve rehab following ACL reconstruction[24].

Presentations[edit | edit source] ACL rehab presentation title slide.png
Non-Operative Management for ACL Deficiency

This presentation, created by Bill Garcia, as part of the Evidence in Motion OMPT Fellowship, discusses the current best evidence for non-surgical rehabilitation of ACL tears.

Non-Operative Management for ACL Deficiency/ View the presentation

References[edit | edit source]

  1. Kyung-Min KiM, Ted Croy, Jay HerTel, SuSan Saliba. Effects of Neuromuscular Electrical Stimulation After Anterior Cruciate Ligament Reconstruction on Quadriceps Strength, Function, and Patient-Oriented Outcomes: A Systematic Review. JOSPT, 2010;40(7):383-391.
  2. 2.0 2.1 2.2 2.3 I Eitzen, H Moksnes, L Snyder-Mackler, MA Risberg. Progressive 5-Week Exercise Therapy Program Leads to Significant Improvement in Knee Function Early After Anterior Cruciate Ligament Injury. JOSPT, 2010;40(11):705-722
  3. 3.0 3.1 3.2 Dr. P. J. Millett et al. ACL Reconstruction Rehabilitation Protocol. Sports Medicine and Orthopaedic Surgery 2010.
  4. 4.0 4.1 4.2 4.3 S. van Grinsven, R. E. H. van Cingel, C. J. M. Holla, C. J. M. van Loon. Evidence-based rehabilitation following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2010; 18:1128–1144
  5. 5.0 5.1 Savio L-Y. Woo, Richard E. Debski, PhD, John D. Withrow, Marsie A. Janaushek. Biomechanics of Knee Ligaments. The American Journal of Sports medicine 1999;27:533
  6. 6.0 6.1 6.2 Rick W. Wright et al. ACL Reconstruction Rehabilitation: A Systematic Review Part I. J Knee Surg. 2008;21(3): 217–224.
  7. 7.0 7.1 7.2 Graham VL. et al. Electromyographic evaluation of closed and open kinetic chain knee rehabilitation exercises. J Athl Train 1993;28(1):23-30.
  8. 8.0 8.1 EB. Bynum et al. Open Versus Closed Chain Kinetic Exercises After Anterior Cruciate Ligament Reconstruction: A Prospective Randomized Study. Am J Sports Med. 1995; 23:401-406.
  9. 9.0 9.1 Prof. dr. P. Vaes. Tekstboek: Onderzoek en behandeling deel IIA 2016
  10. Prof. dr. P. Vaes. Tekstboek: Onderzoek en behandeling deel IIA 2017.
  11. Jewiss D, Ostman C, Smart N. Open versus Closed Kinetic Chain Exercises following an Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis. Journal of Sports Medicine. 2017;2017.
  12. Mike Henkelman. ACL Rehab Forum: Therapy - Week 1. Available from: [last accessed 04/10/14]
  13. Mike Henkelman. ACL Rehab Forum: Therapy - Week 3. Available from: [last accessed 04/10/14]
  14. Mike Henkelman. ACL Rehab Forum: Therapy - Week 5. Available from: [last accessed 04/10/14]
  15. Mike Henkelman. ACL Rehab Forum: Therapy - Week 10. Available from: [last accessed 04/10/14]
  16. Mike Henkelman. ACL Rehab Forum: Therapy - Weeks 12-13. Available from: [last accessed 04/10/14]
  17. Mike Henkelman. ACL Rehab Forum: Therapy - Week 15. Available from: [last accessed 04/10/14]
  18. Kvist J. Rehabilitation Following Anterior Cruciate Ligament Injury Current Recommendations for Sports Participation. Sports Medicine 2004: 269-267.
  19. Atlantic Physical Therapy Center. ACL level 4 Test. Available from:[last accessed 04/10/14]
  20. 20.0 20.1 Gregory D. Myer, Laura C. Schmitt, Jensen L. Brent, Kevin R. Ford, Kim D. Barber Foss, Bradley J. Scherer, Robert S. Heidt Jr., Jon G. Divine, Timothy E. Hewett.Utilization of Modified NFL Combine Testing to Identify Functional Deficits in Athletes Following ACL Reconstruction. J Orthop Sports Phys Ther 2011;41(6):377-387.
  21. Kokmeyer, D., Wahoff M., Myhern M. Suggestions From the Field for Return-to-Sport Rehabilitation Following Anterior Cruciate Ligament Reconstruction: Alpine Skiing. JOSPT, April 2012, 42(4):313-325.
  22. Culvenor AG, Collins NJ, Vicenzino B, Cook JL, Whitehead TS, Morris HG, et al. Predictors and effects of patellofemoral pain following hamstring-tendon ACL reconstruction. J Sci Med Sport. 2015.
  23. DJO Global Products. Biomechanics of the Knee: ACL - with Professor Jim Richards. Available from:[last accessed 04/10/14]
  24. Sven Feil, John Newell, Conor Minogue and Hans H. Paessler. The Effectiveness of Supplementing a Standard Rehabilitation Program With Superimposed Neuromuscular Electrical Stimulation After Anterior Cruciate Ligament Reconstruction: A Prospective, Randomized, Single-Blind Study. Am J Sports Med February 22, 2011 Summary