Rehabilitation of Anterior Cruciate Ligament Injuries

1
Rehabilitation of Anterior Cruciate Ligament
Injuries

• PTRS 970
• Bryan M. Bond
• October 24th, 2008

2
Overview

• Literature Review/Summary
• Rationale
• Hypotheses

3
Literature Review

• Previous research has demonstrated that female
  athletes are four to six times more likely to
  incur a sports-related non-contact anterior
  cruciate ligament (ACL) than male athletes in
  similar high-risk athletics 1, 2

4
Literature Review

• Clinical focus of ACL injury has been two-fold
  post-operative therapy following surgical
  ligamentous repair and injury prevention through
  biomechanical/rehabilitative strategies

5
Literature Review

• One of the clinical dilemmas in ACL
  post-operative care has been the progression of
  initial rehabilitation through return-to-sport
  with optimal clinical and functional outcomes

6
Literature Review

• Current literature for post-injury management of
  ACL injury supports the use of a multi-pronged
  therapeutic approach to include plyometric
  exercise, proprioceptive facilitation,
  power/strength training, endurance training, and
  postural control 3, 8, 9

7
Literature Review

• Evidence-based ACL reconstruction rehabilitation
  guidelines propose the progression to
  return-to-sport include the following four
  stages (I) dynamic stabilization and
  pelvis/abdomen/trunk/hip (CORE) strengthening,
  (II) functional strengthening, (III) power
  development, and (IV) sports performance symmetry
  3

8
Literature Review

• The fundamental concept of non-contact ACL injury
  prevention in male and female athletes is to
  identify clinical risk factors and predictors of
  future injury and further develop valid
  biomechanical/rehabilitative injury reducing
  strategies

9
Literature Review

• Several proposed theories/risk factors to explain
  the pubertal increased incidence of ACL injuries
  in females
• Risk factors for pubescent females include
  anatomic differences (i.e. increased Q angle,
  smaller femoral notch), hormonal influences (i.e.
  estrogen alters ligament strength), and
  neuromuscular imbalances 11
• However, the anatomic and hormonal influences
  require further clarity, but the neuromuscular
  imbalances offer the most significant prospective
  controllable risk factors

10
Literature Review

• The phrase 3-way neuromuscular imbalance
  alludes to three neuromuscular deficits that are
  commonly detected in female athletes 11
• Ligament-dominant
• Quadriceps dominance
• Leg dominance

11
Literature Review

• There is evidence that neuromuscular training
  reduces both the levels of biomechanical risk
  factors for ACL injuries and decreases knee and
  ACL injury incidence in female athletes 13

12
Literature Review
Normal dynamic valgus
Injury Risk
Relative hip knee muscle strength recruitment
Normal joint load
Neuromuscular control
SPURT
Growth Longer Levers Higher forces
SPURT
High joint load Knee abduction moment
Relative hip knee muscle strength recruitment
Injury Risk
Dynamic valgus
Neuromuscular control
Figure 1 Theory linking growth, neuromuscular
adaptation, neuromuscular control, dynamic
valgus, and joint load to ACL injury risk
(Adapted from Myer et al. 2008)2
13
Literature Review

• As female athletes attain maturity, reduced core
  stability may predispose increased dynamic lower
  extremity valgus load (hip adduction and knee
  abduction) during dynamic movements 2
• It has been proposed that core stabilization
  (trunk and hip musculature) is essential in
  modulating lower extremity alignment during
  dynamic tasks 2
• Reduced activation of the trunk and hip
  stabilizers may allow increased lateral shift in
  trunk positions, thus facilitating knee abduction
  loads 2

14
Literature Review

• Willson et al. 14 reported that decreased core
  stability may predispose to lower extremity
  injury and that appropriate training may reduce
  injury
• Zazulak et al. 15 reported that factors related
  to core stability predicted the risk of knee
  injuries in female athletes, but not in male
  athletes

15
Literature Review

• Thus, current research indicates that reduced
  function of the trunk and hip stabilizers, as
  related to core neuromuscular control, may be
  associated with mechanisms of increased ACL
  injury risk in female athletes 15

16
Rationale

• ACL injury prevention appears to be the only
  valuable intervention in managing this
  life-changing injury, particularly in
  consideration of the near 100 risk of
  osteoarthritis (OA) in the ACL injured
  population, with or without surgical repair 2,
  10

17
Hypothesis

• Aim 1 To determine whether reduced function of
  the trunk and hip stabilizers, as related to core
  neuromuscular control, may be associated with
  mechanisms of increased ACL injury risk in female
  athletes.
• Hypothesis 1 There will be differences in trunk
  and hip muscle activation patterns between male
  and female athletes.

18
Hypothesis

• Aim 1 To determine whether reduced function of
  the trunk and hip stabilizers, as related to core
  neuromuscular control, may be associated with
  mechanisms of increased ACL injury risk in female
  athletes.
• Hypothesis 2 These core muscular differences
  will be sufficient to enable prediction of ACL
  injuries in female athletes.

19

• Noncontact ACL Injury

20
Methods

• Prior to testing, subjects and/or guardians will
  be required to sign a consent form, as approved
  by the human subjects committee, outlining
  potential risks associated with this study

21
Methods

• Inclusion criteria
• Male and female post-pubertal athletes aged 14-18
  years recruited from local schools

22
Methods

• Exclusion criteria
• Subjects with current or prior significant hip,
  knee, and ankle injuries including ligamentous
  injuries or other serious soft tissue and/or
  joint injuries that limit function
• Subjects with prior hip, knee, and ankle surgery
  including prostheses, grafts or resections
• Subjects with current low back disorders
  including sprains/strains, disc lesions, or other
  serious pathology

23
Methods

• Nature of subjects athletic pursuits will be
  recorded for analysis
• Height and mass will be documented for each
  subject upon intake

24
Methods

• Male (n 10) and female (n 10) subjects will
  be asked to perform a single-leg hop and balance
  test a total of 6 times (3 randomized trials on
  each leg) on a force platform (AMTI)
• Subjects will be advised to jump laterally 50 cm
  and balance after landing for 10 seconds on the
  same foot

25
Methods

• Maximum vertical ground forces, as well as center
  of pressure (COP) in the medial-lateral and
  anterior-posterior directions will be captured
  for analysis
• Kinematic movements of the trunk and lower
  extremity will be obtained using the motion
  capture system (NDI OPTOTRAK)

26
Methods

• Subjects will have markers placed on the
  following landmarks to assess joint angles
• Trunk (right/left ASIS, and right/left PSIS)
• Thigh (medial/lateral femoral condyles)
• Shank (tibial tuberosity, medial/lateral tibial
  condyles)
• Ankle (medial/lateral malleoli)
• Talus
• Markers will be placed according to International
  Society of Biomechanics (ISB) recommendations
  (2002) to establish the joint anatomical
  coordinate system

27
Methods

• Electromyography (EMG) signal for the trunk and
  lower extremity will be obtained to determine
  core muscle activity during the single-hop task
• Electrodes will be positioned bilaterally on the
  following muscles
• Trunk muscles (rectus abdominis, external
  oblique, internal oblique, latissmus dorsi,
  erector spinae),
• Hip muscles (gluteus maximus, gluteus medius)
• Thigh muscles (vastus medialis, vastus lateralis,
  rectus femoris, biceps femoris, semitendinosus,
  semimembranosus)
• Electrodes will be fastened with tape, and
  attached to the channels on the EMG machine for
  data collection

28
Methods

• EMG signals will be amplified, converted, and
  full-wave rectified
• EMG data will be low-pass filtered and normalized
  to maximum voluntary contractions (MVCs)
• MVCs will be acquired during maximum isometric
  exertion tasks prior to testing
• For each muscle location, the average normalized
  EMG for the events prior take-off and after
  landing will be compared for any differences

29
References

• 1. Mihata, L.C., A.I. Beutler, and B.P. Boden,
  Comparing the incidence of anterior cruciate
  ligament injury in collegiate lacrosse, soccer,
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  cruciate ligament mechanism and prevention. Am J
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• 2. Myer, G.D., et al., Trunk and hip control
  neuromuscular training for the prevention of knee
  joint injury. Clin Sports Med, 2008. 27(3) p.
  425-48, ix.
• 3. Myer, G.D., et al., Neuromuscular training
  techniques to target deficits before return to
  sport after anterior cruciate ligament
  reconstruction. J Strength Cond Res, 2008. 22(3)
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• 4. Ortiz, A., et al., Landing mechanics between
  noninjured women and women with anterior cruciate
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• 5. Ageberg, E., Consequences of a ligament injury
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