Research Review By Gary Maguire©

Date Posted:

August 2010

Study Title:

Current Controversies in Rehabilitation after Anterior Cruciate Ligament Reconstruction


Pezzullo D & Fadale P

Author's Affiliations:

Physical Therapy, University Orthopedics, Inc; and Sports Medicine, University Orthopedics, Inc., Medical Office Center, Providence, RI.

Publication Information:

Sports Medicine & Arthroscopy Reviews 2010; 18(1): 43-47.

Background Information:

Rehabilitation concepts and practices after anterior cruciate ligament (ACL) reconstruction have, and continue to, advance rapidly. A review of the recent literature reveals that numerous aspects of appropriate rehabilitation still require investigation and validation. Today, the quality of the postoperative rehabilitation program has a greater influence that ever before on the timeliness of returning of an athlete to sports and decreasing the risk of re-injury. The aim of this review was to assess the evidence related to perturbation training (i.e. a slight disturbance of a system by a secondary influence), describing criteria-based return-to-sport progressions and functional knee bracing in rehabilitation programs after ACL injuries. The authors specifically emphasized the need for criteria-based progression protocols for the late stages (return to sports) of ACL reconstruction rehabilitation.

The authors express concern that there is a lack of objective rehabilitation progression, specific guidelines or clinical milestones established for late phase/return to sport phase after ACL reconstruction. They feel that late phase ACL rehabilitation should not be determined by the therapist’s clinical intuition and /or left to the athlete’s perceived readiness in returning to sports. They also express concern that the common practice of prescribing functional knee braces after ACL reconstruction is not supported by high level evidence at this time (see Related Reviews below).

Pertinent Results:

In general, the early phases of ACL reconstruction rehabilitation are governed primarily by “time-since-surgery” and specific criterion-based guidelines for progression. In the later stages of ACL reconstruction rehabilitation the progression can become vague and less structured. Often, the late phases of rehab become more time-based and often less emphasis is placed on objective measures of strength, power and functional stability of the knee. Further, the progression is often left to the athlete to determine the basis for perception of readiness.

Reviews by Kvist (1) and Casio et al. (2) investigating the late phases of ACL rehabilitation after reconstruction found that most of the existing studies used time-since-surgery as the primary determinant, but lack any measureable objective tests for the progression of ACL loading, or objective criteria for return to sports. What appears to be lacking in objective measurements of strength, power and functional stability of the knee. A concern raised by the reviewers is the potential attenuation of the ACL graft before developing appropriate muscular strength, power and dynamic stability of the ACL repair when performing high-joint-load functional drills.

Due to this lack of objective progressive criteria one study by Myer et al. (3) attempts to design an algorithm for return-to-sports progression after ACL reconstruction with a criteria-driven progression. Minimum objective criteria are required in this 5-stage return-to-sports progression. The key components are:

Stage 1:
  1. International Knee Documentation Committee (IKDC) score of 70
  2. No functional instability (“giving way” or “buckling”) of the involved knee
  3. A specific baseline Isokinetic strength measure (knee extension peak torque-body mass of 40% for makes and 30% for females at 300?/sec)
Stage 2:
  1. Single limb squat and hold symmetry (minimum of 60° knee flexion held for 5 seconds)
  2. Audibly rhythmic foot strike patterns without gross asymmetries in visual kinematics when running (Treadmill 6-10 mph)
  3. Acceptable single limb balance scores on Stabilometer (females < 2.2°and males < 3° of deflection; total sway tested for 30 seconds at level 8)
Stage 3:
  1. side-to-side symmetry of peak torque knee flexion and extension (within 15% at 180° and 300°/second) and hip abduction peak torque symmetry (within 15% at 60° and 120°/second)
  2. Plantar force total loading symmetry measured during squat at 90°knee flexion (< 20% discrepancy between sides)
  3. Single limb peak landing force symmetry on a 50cm hop (< 3 x body mass and within 10% between sides)
Stage 4:
  1. Single limb hop for distance (within 15% side to side)
  2. Single limb cross over triple hop for distance (within 15% side to side)
  3. Single limb vertical power hop (within 15% side to side)
  4. Re-assessment of tuck jump (15 percentage point improvement or a score of 80 on IKDC
Stage 5:
  1. Drop vertical jump landing force bilaterally symmetrical (within 15%)
  2. Modified Agility T-Test (test time within 15% side to side)
  3. Single limb average peak power test for 10 seconds (symmetrical within 15%)
  4. Re-assessment of tuck jump (20 percentage point improvement from initial test or a perfect score of 80 on IKDC)
The criteria for progression of each of the five stages are operationally defined and performance errors are identified during functional testing that would prohibit advancement to the next stage. While most of the tests are functional (hop tests, tuck jumps, agility t-tests, vertical jumps) some of the objective criteria require measurement with equipment (Isokinetic systems) that is not available in most outpatient rehabilitation settings.

Next the investigators targeted functional knee bracing. Functional bracing after ACL reconstruction surgery continues to create controversy. In response to a recent survey (4), 87% of the orthopedic surgeons prescribed functional knee braces for their patients after ACL reconstruction.

Numerous studies and review articles show the limited effect that functional knee braces have on knee joint stability, reinjury rates and kinesthetic awareness. McDevitt et al. (5) conducted a prospective randomized clinical trial to assess the effectiveness of functional knee bracing after ACL repair consisting of 100 patients and following them over a two year period found no statistical difference in the brace versus nonbrace group.

Birmingham et al. (6 – see related reviews below) conducted a randomized controlled trial comparing the use of a traditional functional knee brace with a neoprene sleeve after ACL repair. The study included 150 patients who were randomly assigned. The groups were compared at 6 weeks and 6, 12 and 24 months after surgery and the results showed no statistical significance in any outcome measure at 1 and 2 years follow-up.

One study does support sport specific knee bracing (skiing) after ACL reconstruction. This 6 year study conducted by Sterett et al. (7) involved 820 skiers who had an ACL reconstruction 2 or more years ago. During the study 257 patients wore a functional knee brace and 563 opted against utilizing one. The results revealed that the nonbraced skiers were 2.74 times more likely to suffer a knee injury than a skier in the brace group.

Clinical Application & Conclusions:

Loss of range of motion, strength, power and abnormal gait mechanics are common findings after acute ACL injury. The goal of the rehabilitation specialist is to eliminate these deficits or abnormalities as effectively, efficiently and safely as possible. The literature strongly suggests that perturbation training/neuromuscular training to restore normal knee kinematics and dynamic knee stabilization are effective strategies.

This literature review emphasizes the promising evidence suggesting that perturbation training plays a vital role in ACL rehabilitation programs and returning athletes to sports participation. It is clear that there is a lack of objective measures and functional tests that can be reproduced in sports medicine clinics and there is a need for advancing late phase objective testing and guidelines.

Perturbation exercises are used to re-establish neuromuscular control and dynamic stability of the knee joint after injury or surgery. The exercises involve controlled delivery of forces to the lower extremity in various directions while the patient stands on an unstable surface. The goal is to deliver destabilizing forces to the lower extremity in order to produce compensatory muscle activity that provides improved joint stability.

Fitzgerald et al. (8) have concluded that perturbation training is 4.88 times more likely to provide a successful outcome (absence of giving way) than a standardized training program without perturbation training. The theory is that this type of training may provide a protective effect and allow for participation in higher level athletic activity. Other studies also promote perturbation training for improving coordinated muscle activity, improved symmetrical gait patterns and strength in ACL-deficient knees as well.

The supportive evidence suggests that perturbation training should be included in both the preoperative and the postoperative ACL reconstruction rehabilitation programs. This is also seen as an important component in late phase ACL rehabilitation protocols for continued advancement in achieving functional outcomes.

The investigators also demonstrated that there is a significant cost related to, and lack of evidence in support of, functional knee bracing and that it is difficult to include it as a component of standard ACL rehabilitation protocols especially in an era of rising healthcare costs. The findings suggest that the use of a brace is recommended on a case-by-case basis (e.g. Skiing).

The suggested rehabilitation progression outlined above can also be implemented, depending on the equipment available in your office.

Review Strengths / Weaknesses:

The weakness of this literature review is that these are two separate but important ACL rehabilitation issues (perturbation training and functional knee racing) and the literature reviewers would have been better to focus each component as an individual review to provide more information, guidelines and validity of protocols for comparison.

The criteria-based progression through the return-to-sport program presented by Myer et al. is a novel effort to provide objective steps in returning an athlete to sports participation. Further research can expand on this model and test its utility.

The reviewers emphasize the importance of perturbation training in their review, but do not provide the reader with background understanding of neurophysiology for perturbation training. The review should have discussed the interaction between static and dynamic components of functional stability and that it is meditated by the neuromuscular system.

In the classic sense, proprioception is a specialized variation of the sensory modality touch. It refers to position sense and movement sense arising from the mechanoreceptors and is the basis for neuromuscular training aka perturbation training.

Additional References:

  1. Kvist J. Rehabilitation following anterior cruciate injury. Current recommendations for sports participation. Sports Med. 2004;34:269-280.
  2. Casio B et al. Return to play after anterior cruciate ligament reconstruction. Clin Sports Med. 2004;23:395-408. Myer G et al. Rehabiliation after anterior cruciate ligament reconstruction: criteria-based progression through the return-to-sport phase. J Orthop Sports Phys Ther. 2006;36:385-402.
  3. Decoster L & Vailis . Functional anterior cruciate ligament bracing: a survey of current brace prescription patterns. Orthop 2003; 26: 701-706.
  4. McDevitt E et al. Functional bracing after anterior cruciate ligament reconstruction.: A prospective, randomized, multicenter trial. Am J Sports Med 2004; 32: 1887-1892.
  5. Birmingham TB et al. A randomized controlled trial comparing the effectiveness of functional knee brace and neoprene sleeve use after anterior cruciate ligament reconstruction. Am J Sports Med 2008; 36: 648-655.
  6. Sterret W et al. Effect of functional bracing on knee injury in skiers with anterior cruciate ligament reconstruction: A prospective cohort study. Am J Sports Med 2006; 34: 1581-1585.
  7. Fitzgerald GK et al. The efficacy of perturbation training in nonoperative anterior cruciate ligament rehabilitation programs for physically active individuals. Phys Ther 2000; 80: 128-140.