Understanding and Preventing Noncontact ACL Injuries

344 Pages·2007·2.67 MB·English

by  American Orthopaedic Society for Sports Medicine

Understanding
and Preventing
Noncontact
ACL Injuries
American Orthopaedic Society for
Sports Medicine
Note: This e-book reproduces the text of the printed book,
but it may not include images, tables, or figures that have restrictions
on electronic distribution.

Understanding
and Preventing
Noncontact
ACL Injuries
American Orthopaedic Society for
Sports Medicine
Editors
Timothy E. Hewett
Sandra J. Shultz
and Letha Y. Griffin
Human Kinetics
Library of Congress Cataloging-in-Publication Data
Understanding and preventing noncontact ACL injuries / American Orthopaedic Society for
Sports Medicine ; Timothy E. Hewett, Sandra J. Shultz, Letha Y. Griffin, editors.
p. ; cm.
Includes bibliographical references and index.
ISBN-13: 978-0-7360-6535-1 (hard cover)
ISBN-10: 0-7360-6535-0 (hard cover)
1. Anterior cruciate ligament--Wounds and injuries--Prevention. 2. Sports injuries--
Prevention. 3. Knee--Wounds and injuries--Prevention. I. Hewett, Timothy E. II. Shultz,
Sandra J., 1961- III. Griffin, Letha Y. IV. American Orthopaedic Society for Sports
Medicine.
[DNLM: 1. Anterior Cruciate Ligament--injuries. 2. Athletic Injuries--prevention &
control. 3. Knee Injuries--prevention & control. WE 870 U55 2007]
RD561.U53 2007
617.4’7044--dc22
2006038700
ISBN-10: 0-7360-6535-0 (print) ISBN-10: 0-7360-9088-6 (Adobe PDF)
ISBN-13: 978-0-7360-6535-1 (print) ISBN-13: 978-0-7360-9088-9 (Adobe PDF)
Copyright © 2007 by American Orthopaedic Society for Sports Medicine
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Contents
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvii
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
An Introduction to Understanding and Preventing ACL Injury . . . . . . xxi
Timothy Edwin Hewett, PhD, FACSM
The incidence of anterior cruciate ligament (ACL) injuries in young athletes
(<25 years of age) remains high. Despite early recognition, initial appropri-
ate care, adequate surgical stabilization (if needed), and a well-structured
rehabilitation program, arthritis of the injured knee frequently develops.
Therefore, prevention strategies to decrease its incidence are needed. This
book presents the latest research on the causes and prevention of ACL
injuries, particularly among female athletes. In particular, we review the
effects of programs that have been recently developed to prevent ACL injury
and address the following questions: What are the essential components of
effective programs? What do the various programs have in common, and
can one assume that these shared components are, therefore, the essential
components of an ACL prevention program? How do these programs favor-
ably alter neuromuscular risk factors; or, stated in an alternative way, how
do they influence biomechanics to decrease risk? What new information on
risk factors has come forth that could be used to improve or broaden our
present thoughts on prevention strategies or more reliably identify those
at increased risk of sustaining an ACL injury?
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxviii
Part I The Problem of ACL Injuries 1
Part Editor: Letha Y. Griffin, MD, PhD
Chapter 1 Incidence of ACL Injury . . . . . . . . . . . . . . . . . . . . . . . 5
Stephen W. Marshall, PhD; Darin Padua, PhD, ATC;
and Melanie McGrath, MS, ATC
The goal of this chapter is to examine advances in data collection and
changes in incidence data regarding noncontact ACL injury. Significant
progress has been made in the last five years in developing mechanisms
to collect more detailed information on ACL injuries, particularly at the
collegiate level. Despite initiation of prevention efforts, the overall risk of
ACL injuries in collegiate female soccer and basketball has not declined
since 1998, and the risk is still three to four times that of male counterparts
in these sports. Anterior cruciate ligament injuries also are a concern in
other contact (football) and noncontact (gymnastics) sports; prevention
efforts should be focused on these activities as well. Rule modifications
implemented at the sport governing board level may be another way to
enhance prevention efforts, particularly in contact situations.
v
vi Contents
Human Movement and ACL Injury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
What Is Incidence? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
What Is the Average Incidence of ACL Injury in the General Population? . . . . . . . . . . . . 7
National Ambulatory Care Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
How Does ACL Injury Incidence Vary by Age and Gender?. . . . . . . . . . . . . . . . . . . . . . . 9
How Does the Incidence of ACL Injury Vary by Sport and Gender? . . . . . . . . . . . . . . . 12
Literature Review Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Abstraction of Incidence Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
General Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Synthesis and Commentary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Recommendations for Future Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Chapter 2 Does ACL Reconstruction Prevent Articular
Degeneration? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
The ACL Risk Equation
Paul H. Marks, MD; Kurt P. Droll, MD, MSc, FRCSC; and Michelle
Cameron-Donaldson, MD
Osteoarthritis is found more commonly in the knee than in any other
weight-bearing joint in the human body. Individuals with ACL insuffi-
ciency have been found to have a higher risk for developing osteoarthritis
in the knee compared to the general population. Several risk factors have
been implicated in the development of osteoarthritis in the ACL-deficient
knee, including concomitant meniscal pathology, osteochondral pathol-
ogy, impaired proprioception, and biomechanical mediators. The chapter
reviews the evidence pertaining to these risk factors. In addition, in an
effort to aid in the future prognosis of posttraumatic osteoarthritis, we
propose that an “ACL risk equation” be developed that would express
overall osteoarthritis risk quantitatively. This proposed equation would
be a function of all the pertinent risk factors.
Meniscal Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Osteochondral Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Impaired Proprioception. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Biochemical Mediators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Summary and Future Work. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Chapter 3 The Costs Associated With ACL Injury. . . . . . . . . . . 47
Timothy Edwin Hewett, PhD, FACSM;
and Bohdanna T. Zazulak, DPT, MS, OCS
In this chapter, we review the financial and emotion burdens placed on
individuals, families, and societies from ACL injuries. We compare these
costs with the amount of federal funding that has been expended to research
ACL injuries and their prevention. We also present an analysis of the
potential savings that would occur if ACL injury prevention programs were
instituted on a more extensive basis. It is concluded that greater awareness
Contents vii
at both the governmental and public levels is needed to enhance efforts to
reduce the incidence of ACL injury.
Who Pays for ACL Injury Prevention in the High-Risk Female Athlete?. . . . . . . . . . . . . 52
Informing the High-Risk Female Athlete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Part II ACL Injury Prevention Programs 57
Part Editor: Timothy Edwin Hewett, PhD, FACSM
Chapter 4 Components of Prevention Programs. . . . . . . . . . . . . 61
Holly J. Silvers, MPT
Twelve ACL intervention programs that have empirically evaluated
outcomes were identified. A component analysis of these programs was
performed to identify some of the commonalities among successful ACL
intervention protocols. Numerous deficits have been identified in the high-
risk female adolescent population. These include faulty landing kinematics
(hip and knee extension with valgus perturbation), decreased core stability,
decreased hamstring contraction times, decreased hamstring and abductor
dynamic control, excessive tibial torsion, and subtalar pronation. The exist-
ing programs focus on neuromuscular and proprioceptive interventions in
the female athletic population in order to reduce the rate of ACL injury in
this population. The commonalities of successful programs are discussed.
Chapter 5 Theories on How Neuromuscular Intervention
Programs May Influence ACL Injury Rates . . . . . . . . 75
The Biomechanical Effects of Plyometric, Balance, Strength,
and Feedback Training
Timothy Edwin Hewett, PhD, FACSM; Gregory D. Myer, MS, CSCS;
and Kevin R. Ford, MS
A systematic review of the published literature yielded six studies of interven-
tions targeted toward knee or ACL injury prevention in female athletes. Five
of the six interventions were reported to reduce injury incidence, four of the
six reduced knee injury incidence, and three of the six reduced ACL injury
incidence in females. Examination of the similarities and differences among
the training regimes gives insight into the development of more effective and
efficient interventions. The purpose of this review is to highlight the relative
effectiveness of these interventions in altering landing techniques and dynamic
balance, as well as the common components of the training. This review
focuses on the common components of the various interventions in order to
discuss their potential to reduce ACL injury risk and assess their potential
for combined use in more effective and efficient intervention protocols.
Single-Component Training. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Multicomponent Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Effects of a Comprehensive Program Combined With Either Plyometric
or Balance Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Conclusions and Future Directions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
viii Contents
Chapter 6 Preventive Training Programs . . . . . . . . . . . . . . . . . . 91
Changing Strength Ratios Versus Positions of Muscular Effi ciency
Sandra J. Shultz, PhD, ATC, CSCS
Considering the strain patterns and the observed neuromuscular and
biomechanical differences noted in males and females, injury prevention
programs have attempted to improve both movement strategies and neu-
romuscular coordination and strength patterns to reduce these injurious
forces. This chapter focuses on the potential for these programs to affect
agonist–antagonist muscle strength ratios that may improve knee stability
and reduce ACL injury risk.
Thigh Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Hip Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Core Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Chapter 7 Effect of Prevention Programs on Performance . . . . 103
Christopher M. Powers, PhD, PT; Christine D. Pollard, PhD, PT;
and Susan M. Sigward, PhD, PT, ATC
To address resistance from coaches and players as to participating in ACL
injury prevention programs and program evaluation, the performance
enhancement aspects of these programs are often emphasized. We review
the limited data relating to the premise that ACL injury prevention pro-
grams improve performance or the key elements underlying performance.
We conclude that the evidence to support this premise is inconsistent and
that the literature is characterized by a small number of studies, moderate
sample sizes with no control group data, and utilization of variable train-
ing programs. On the other hand, various forms of training (not related
to ACL injury prevention) have been shown to reliably improve the basic
components of sport performance. It therefore stands to reason that ACL
injury prevention programs should be able to accomplish the same results
given an adequate stimulus for a given outcome of interest. Much more
high-quality research, however, is needed to verify this speculation.
Performance Measure: Vertical Jump Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Performance Measures: Agility, Strength, and Lunge Distance . . . . . . . . . . . . . . . . . . . 105
Performance Measures: Vertical Jump Height, Single-Leg Hop, Speed, and Strength . . . 106
Performance Measure: Single-Limb Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Performance Measures: Balance, Strength, Single-Leg Hop, Triple Jump,
and Stair Hop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Chapter 8 Congruence Between Existing Prevention Programs
and Research on Risk Factors and Mechanisms of
Noncontact ACL Injury . . . . . . . . . . . . . . . . . . . . . . 109
William E. Garrett, Jr., MD, PhD; and Bing Yu, PhD
In order to develop effective prevention programs, we must know how the
injury happens, know what is injured, identify the risk factors, be able
Contents ix
to study the injury in the lab, try to devise prevention strategies, test the
prevention strategies, and continually revise the prevention strategies. The
prevention programs that have been developed to date target known risk
factors, yet several unanswered questions remain. For example, do these
training effects generalize to the competitive situation? Do they lead to long-
term behavior change? Do they have sufficient power for a reasonable effect
size? Do they address potentially important but unexplored variables such as
stretching and endurance? Finally, must these programs be completed exactly
as prescribed, or can they serve as suggestions for a variety of activities?
This chapter explores possible answers to these questions and proposes one
central skill that may be the most effective in reducing injury incidence.
ACL-Loading Mechanisms and Risk Factors for Noncontact ACL Injury. . . . . . . . . . . 109
Current Training Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Future Training Program Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Chapter 9 Discussion, Summary, and Future Research Goals . . 121
Lars Engebretsen, MD, PhD
This chapter summarizes issues related to successful prevention programs
that have recently been evaluated. This includes a discussion of the nature
of interventions (cognitive and psychomotor approaches), delivery mecha-
nisms, duration, and follow-up. In addition, we offer suggestions regarding
needs for future prevention programs.
Part III Biomechanical and Neuromuscular
Mechanisms of ACL Injuries 129
Part Editor: Timothy Edwin Hewett, PhD, FACSM
Chapter 10 Biomechanics Associated With Injury. . . . . . . . . . . 131
Athlete Interviews and Review of Injury Tapes
Tron Krosshaug, PhD; and Roald Bahr, MD, PhD
A precise description of the biomechanics associated with injury—the
injury mechanism—is a key component to understanding the causes of
any particular injury type in sport. However, any attempt to describe the
injury mechanisms raises a number of issues. A complete understanding
of injury causation needs to take into account the multifactorial nature of
sport injuries—not only the injury biomechanics, but also the risk factors
associated with an increased risk of injury. This chapter reviews studies
aimed at assessing multiple variables associated with the specific event
in which a noncontact ACL injury occurred, including studies in which
athletes have been interviewed about their recollection of these variables
and studies in which videotapes of injury events have been analyzed.
Defining “Injury Mechanisms”. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Describing the Inciting Event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Research Approaches to Describe the Injury Mechanisms . . . . . . . . . . . . . . . . . . . . . . 134
Literature Search. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Athlete Interviews. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
x Contents
Video Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Chapter 11 Clinical Biomechanical Studies on
ACL Injury Risk Factors . . . . . . . . . . . . . . . . . . . . . 141
Laura J. Huston, MS
This chapter reviews clinical studies that have investigated the biome-
chanics of ACL injury. It is concluded that kinematic and kinetic gender
differences exist that may render women more susceptible than men to
ACL injury. The most prevalent differences that females exhibited, either
when landing from a jump or during a cutting and pivoting maneuver, were
reduced hip and knee flexion angles, increased knee valgus, internal rota-
tion of the femur, high quadriceps activity unbalanced by the hamstrings,
and inadequate generation of trans-knee muscle stiffness.
Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Kinematic and Kinetic Differences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Jump Landings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Sidestep and Cutting Maneuvers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Muscular Differences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Chapter 12 Effects of Neuromuscular Training on
Lower Extremity Motion Patterns . . . . . . . . . . . . . . 155
Bing Yu, PhD; and Marlene DeMaio, MD
Understanding the biomechanical changes following training programs is
critical in the development of intervention strategies for reducing the risk of
sustaining noncontact ACL injuries. Scientifically evaluating the effectiveness
of these training programs is difficult. It is helpful to have a good understand-
ing of the effects of various exercises on the biomechanics of the movements
in those athletic tasks in which noncontact ACL injuries frequently occur.
Such understanding will not only assist clinicians and scientists in deciding
which exercises to include in intervention programs, but also provide indirect
evidence to support the effectiveness of intervention programs. Biomechani-
cal studies with sophisticated modeling techniques to estimate in vivo ACL
loading in athletic tasks are particularly needed to elucidate cause-and-effect
relationships between movements and ACL loading and injuries. These types
of biomechanical studies will be critical tools for identifying specific motor
control–related biomechanical risk factors, as well as for evaluating interven-
tion programs aimed at reducing the risk of noncontact ACL injuries.
Combined Training Programs Including Plyometrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Chapter 13 Sport-Specific Injury Mechanisms Associated
With Pivoting, Cutting, and Landing. . . . . . . . . . . . 163
Mary Lloyd Ireland, MD
The typical mechanism of ACL injury in basketball, soccer, and team
handball is a rapid but awkward stop and anticipation of lateral move-