The anterior cruciate ligament (ACL) is one of four ligaments that provide stability to the knee. The ACL is located in the center of the knee and helps control forward and rotational movement of the tibia (shin bone). Approximately 30% of ACL injuries are due to contact, for example a tackle.2 The majority of ACL tears are noncontact and are associated with awkward landings, pivoting, accelerating and decelerating 1,2.
Risk Factors May Include
- High level of friction between shoes and playing surface 2
- Higher than average body mass index (BMI) in women7,8
- Increased knee laxity 1,8
- Certain aspects of knee anatomy and family predisposition (not modifiable, genetic)1,7,8,9
- Female gender with risk increasing during certain times of the menstrual cycle 1, 8
- Prior ACL reconstruction 9
- Awkward jump landings 9
Female athletes who sustain ACL injuries are also more likely to have had a previous ankle sprain on the side of the injured knee10.
In the United States, between 80,000 and 250,000 ACL tears occur annually 1. Most ACL injuries occur between the ages of 15 and 45 and 70% of these are the result of a sporting activity.2 More men sustain this injury due to greater sports participation, but women are 2 to 9.7 times more likely to injure the ACL.1,3
ACL prevention programs can be effective for reducing the risk of ACL injury and many of these programs can be performed as a warm-up prior to engaging in sports11. Depending on the program, between 5 and 187 athletes must participate to prevent one ACL tear 11. This indicates these programs may be particularly beneficial when implemented in larger groups such as those found in school athletics.
Physical Therapy Treatment
Surgery may be recommended and in some cases the patient may be managed non-operatively with physical therapy.1,4,5 Approximately 100,000 ACL surgeries are performed a year.1 The percentage of those returning to their prior level of sport participation after reconstruction ranges from 43% to 92%. 6
In the active patient a successful ACL reconstruction outcome requires physical therapy, which may consist of:
- Ice 1
- Range of motion of the knee which is often started early 1,13
- Strengthening 1
- Electrical stimulation 14
- Balance and coordination training 1
In non-operatively managed patients bracing may be beneficial particularly if they are a skier. 1,12
Physical therapy after surgical management tends to be progressed in phases at the discretion of the orthopedic surgeon. Post-surgical rehabilitation protocols typically allow a return to sport specific activities at 4-6 months and full return to sports at 6-12 months.1
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1. Logerstedt, David S., et al. “Knee Stability and Movement Coordination Impairments: Knee Ligament Sprain: Clinical Practice Guidelines Linked to the International Classification of Functioning, Disability, and Health from the Orthopaedic Section of the American Physical Therapy Association.” The Journal of orthopaedic and sports physical therapy 40.4 (2010): A1.
2. Griffin LY, Agel J, Albohm MJ, et al. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8:141-150.
3. Arendt, Elizabeth A., Julie Agel, and Randall Dick. “Anterior cruciate ligament injury patterns among collegiate men and women.” Journal of Athletic Training34.2 (1999): 86.
4. Hurd WJ, Axe MJ, Snyder-Mackler L. A 10-year prospective trial of a patient management algorithm and screening examination for highly active individuals with anterior cruciate ligament injury: Part 1, outcomes. Am J Sports Med. 2008;36:40-47.
5. Hurd, Wendy J., Michael J. Axe, and Lynn Snyder-Mackler. “A 10-Year Prospective Trial of a Patient Management Algorithm and Screening Examination for Highly Active Individuals With Anterior Cruciate Ligament Injury Part 2, Determinants of Dynamic Knee Stability.” The American journal of sports medicine 36.1 (2008): 48-56.
6. Reconstruction, Cruciate Ligament. “Time line for noncopers to pass return-to-sports criteria after anterior cruciate ligament reconstruction.” journal of orthopaedic & sports physical therapy 40.3 (2010): 141.
7. Uhorchak JM, Scoville CR, Williams GN, Arcerio RA, St Pierre P, Taylor DC. Risk factors associated with noncontact injury of the anterior cruciate ligament: a prospective four-year evaluation of 859 West Point cadets. Am J Sports Med. 2003;31:831-842.
8. Smith, Helen C., et al. “Risk Factors for Anterior Cruciate Ligament Injury A Review of the Literature—Part 1: Neuromuscular and Anatomic Risk.” Sports Health: A Multidisciplinary Approach 4.1 (2012): 69-78.
9.. Smith, Helen C., et al. “Risk Factors for Anterior Cruciate Ligament Injury A Review of the Literature—Part 2: Hormonal, Genetic, Cognitive Function, Previous Injury, and Extrinsic Risk Factors.” Sports Health: A Multidisciplinary Approach 4.1 (2012): 155-161.
10. Kramer, L. C., et al. “Factors associated with anterior cruciate ligament injury: history in female athletes.” Journal of sports medicine and physical fitness47.4 (2007): 446-454.
11. Sadoghi, Patrick, Arvind von Keudell, and Patrick Vavken. “Effectiveness of anterior cruciate ligament injury prevention training programs.” The Journal of Bone & Joint Surgery 94.9 (2012): 769-776.
12. Sterett, William I., et al. “Effect of Functional Bracing on Knee Injury in Skiers With Anterior Cruciate Ligament Reconstruction A Prospective Cohort Study.”The American journal of sports medicine 34.10 (2006): 1581-1585.
13. Beynnon, Bruce D., Robert J. Johnson, and Braden C. Fleming. “The science of anterior cruciate ligament rehabilitation.” Clinical orthopaedics and related research 402 (2002): 9-20.
14. Wright, Rick W., et al. “A systematic review of anterior cruciate ligament reconstruction rehabilitation.” J Knee Surg 21 (2008): 225-234.