Anterior Cruciate Ligament (ACL) Rehabilitation

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Original Editors

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Search Strategy

Search engines: PubMed, Pedro
Key words: anterior cruciate ligament, Open chain exercises, Closed chain exercises, ACL rehabilitation,…

 Definition/Description

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[1] (Level A).

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[3] (Level A).

Clinically Relevant Anatomy

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Evidence

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](Level 2B).

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](Level A).
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](Level B).

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](Level 2B).
There is also a study who concluded that CKC-exercises are safe and effective and offer some important advantages over open kinetic chain exercises[6] (Level 1B).
 

Characteristics/Clinical Presentation

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Differential Diagnosis

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Diagnostic Procedures

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Outcome Measures

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Examination

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Medical Management

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 Physical Therapy Management

 

1. Open-Kinetic-Chain exercises:

1.1. Characteristics

 - Non-weight bearing

-  Movement occurring at a single joint

-  Distal segment free to move

-  Resistance is usually applied to the distal segment

1.2. Open-Kinetic-Chain Knee-Extension exercises

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](Level 2B).

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] (Level 2B).

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.

1.3. Open-Kinetic-Chain Knee-Flexion exercises

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^[10] ( Level 2B).

2. Closed-Kinetic-Chain Knee exercises:

2.1. Characteristics

- Weight bearing
- Movement at several joints
- Distal segment fixed to a surface
- Resistance may be applied both proximally and distally

2.2. Closed-Kinetic-Chain Knee exercises

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 tibiofemorale joint compression, that also reduces tibiofemoral shear forces ^[7] (Level A).

CKC exercises have several advantages compared with OKC exercises^[12] (Level F).

• Increase stability in the knee joint (more joint compression)
• Functional load
• Strong coordinative training
• Minimal shear force
• Less stress on the ACL
• 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

3. Examples

3.1. Postoperative phase 1 ( 1-5 weeks)

• Exercises 1:

The first CKC-exercises are sitting exercises because they facilitate flexion and extension movements in the knee [9] (Level A).

The patient lying on a table has to extend the knee against resistance from a stretcher.

Key Research

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Resources

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Clinical Bottom Line

Further research into this topic is required. Future studies should aim to use higher order experimental design and have better methodological quality, including at a minimum, single blinding, larger sample size, use of control groups, and reporting of statistical data such as effect size, confidence  intervals and standard deviations.
The lack of high evidence and good quality studies constrains the formulation of clear clinical recommendations regarding the effect of closed versus open kinetic chain exercises on ACL strain. Thus the findings of this review must be interpreted with caution. Nevertheless the findings support the conclusion that CKC exercises generally produce less strain/stress on ACL and have a greater functional impact than OKC exercises. Thus the cautious clinical recommendation would be to use CKC exercises or a combination of CKC and OKC exercises rather than OKC exercises alone[11](Level 1A).

Recent Related Research (from Pubmed)

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References

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