ACL Injuries in Female Athletes

Robin West, Brandon Bryant, Robin West, Brandon Bryant

• Publisher: Elsevier
• Year: 2018
• Print ISBN: 9780323548397
• eBook ISBN: 9780323548403
• Topic: Medicine
• Subtopic: Orthopedics

This easy-to-read reference presents a succinct overview of clinically-focused topics covering the prevention, treatment, and rehabilitation of ACL injuries in the female athlete. Written by two professional team physicians, it provides practical, focused information for orthopaedic and sports medicine surgeons and physicians.- Covers ACL injury risk factors and prevention, including biomechanics, biology, and anatomy of the female athlete.- Discusses graft choices, the biology of healing, rehabilitation and return to play, future options for treatment, and more.- Addresses special considerations such as pediatric ACL and revision ACL.- Consolidates today's available information and experience in this timely area into one convenient resource.

Chapter 1

Anterior Cruciate Ligament Ruptures in the Female Athlete

An Injury Epidemic

Miguel A. Pelton, MD, and Edward S. Chang, MD

Abstract

As sports participation continues to increase, especially among the youth, anterior cruciate ligament (ACL) injuries remain a significant concern for female athletes. Most epidemiologic studies estimate that female athletes are two to eight times more likely to sustain an ACL injury than male athletes. Furthermore, females are at greater risk to rupture the contralateral ACL following returning to play from an ACL injury. Several sports have intrinsic risk factors to create the potential for injuries in the at-risk knee. Certain anatomic and neuromuscular differences may contribute to the higher rates seen in females. Multiple neuromuscular and proprioceptive protocols have been designed and early studies are promising, showing reduced incidence of ACL injury following completion of the program. Further research is necessary to identify the main risk factors for ACL injuries in female athletes and, just as important, correct the modifiable factors.

Keywords

ACL prevention; ACL tear; Anterior cruciate ligament; Female knee injuries

Introduction

Each year in the United States, approximately 250,000 anterior cruciate ligament (ACL) injuries occur. Mall et al.¹ reported an increase in ACL reconstruction from 32.94 per 100,000 person-years in 1994 to 43.48 per 100,000 person-years in 2006. This is likely attributed to both an increase in sports participation and a heightened awareness of the injury.

Females have consistently been shown to be more at risk for these injuries in a disproportionate manner, with a four- to six-fold increased risk of rupture.^2,3 One recent epidemiologic study assessed the trends of ACL injuries from 2002 to 2014 and the subsequent reconstruction procedures and found that the rates of ACL reconstruction per 100,000 person-years rose by 22%, i.e., from 61.4 in 2002 to 74.6 in 2014. During this period, females experienced a more rapid increase in reconstruction rate than males (34% vs. 13%, P < .01).⁴ The often cited reasons for this increased risk of injury in female athletes include decreased neuromuscular control, smaller notch width, increased Q angles, and genetic and hormonal effects on type I collagen tissue.⁵

Epidemiologic studies have elucidated current and past trends with certain female sports and ACL injuries. Disproportionately affected sports include activities in which pivoting and cutting forces further strain an already “at-risk” ligament. Such sports include soccer, field hockey, volleyball, and gymnastics. This chapter evaluates the latest literature on epidemiologic trends of ACL injuries in female athletes. It will touch on the pathophysiology but will mostly focus on the most commonly affected sports and activities further stratified by age ranges. Lastly, the role of prevention programs in decreasing ACL injury rates in the female patient will be assessed.

Pathophysiology

A noncontact pivoting moment on a flexed knee has been thought of as the main reason for an ACL rupture. This most commonly occurs while landing from a jump, sudden change of direction, or deceleration. Valgus collapse at the knee, decreased knee flexion angles (<30 degrees), and increased hip internal rotation are often reported during ACL injuries. Biomechanical studies have further shown the ACL to be under greater stress at this position⁶ (Fig. 1.1).

A kinematic study assessed the peak cartilage pressures during landing from a drop vertical jump in young female athletes who went onto to develop ACL injury.⁶ This group was compared with a group of females without subsequent ACL injury who performed the same kinematic testing, and it was found that the highest ACL strains occurred in the combined knee abduction/anterior tibial translation condition in the group that had a baseline knee abduction angle of 5 degrees. These injuries subsequently correlated to the bone bruise patterns noted on the lateral femoral condyle and posterolateral proximal tibia, likely from the valgus collapse.

Another study analyzed 205 female athletes in high-risk sports (soccer, volleyball, and basketball) and found that knee abduction angles of 8 degrees or higher, increased abduction/valgus moments, and increased ground reaction forces all increased the risk of ACL injuries.⁷

Multiple investigators have explored the details of the mechanism for failure.^7,8 Although certain anatomic factors in females (small notch width, increased Q angle, increased posterior tibial slope) have been associated with increased risk of injury, much of the recent interest and research has been on the biomechanical and neuromuscular factors related to ACL injury in females.

Four theories have been introduced to describe the biomechanics and neuromuscular role in ACL injury: the ligament dominance theory, the trunk dominance theory, the quadriceps dominance theory, and the leg dominance theory⁸ (Table 1.1).

The ligament dominance theory suggests that female athletes at high risk perform athletic maneuvers with excessive knee valgus, hip adduction, and hip internal rotation. The trunk dominance theory suggests that poor trunk and core control during athletic maneuvers leads to increased risk for ACL injury. The quadriceps dominance theory suggests that excessive relative quadriceps forces or reduced hamstring recruitment places the ACL at high risk for injury. Lastly, the leg dominance theory suggests that large leg-to-leg asymmetries predispose athletes to injury.⁸

FIG. 1.1 Proposed mechanism for anterior cruciate ligament (ACL) injuries in females. Combination of motions and rotations at all three lower extremity joints, potentially including hip adduction and internal rotation, knee abduction, tibial external rotation and anterior translation, and ankl...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Preface
• Chapter 1. Anterior Cruciate Ligament Ruptures in the Female Athlete: An Injury Epidemic
• Chapter 2. Epidemiology
• Chapter 3. Anterior Cruciate Ligament Prevention Programs Overview
• Chapter 4. Anterior Cruciate Ligament Anatomy
• Chapter 5. Anterior Cruciate Ligament Graft Choices in the Female Athlete
• Chapter 6. The Biology of Anterior Cruciate Ligament Healing After Reconstruction
• Chapter 7. Special Considerations: Pediatric Anterior Cruciate Ligament
• Chapter 8. Special Considerations: Revision Anterior Cruciate Ligament
• Chapter 9. Anterior Cruciate Ligament Rehabilitation and Return to Play
• Chapter 10. The Future: Orthobiologics and Anterior Cruciate Ligament Injury
• Chapter 11. Psychology of Return to Play After Anterior Cruciate Ligament Injury
• Index