This document discusses prevention and rehabilitation of ACL injuries through proper warm-up, strengthening, plyometrics, and agility training. It outlines the components of an ACL injury prevention program, including warming up for 15 minutes prior to practice or games 2-3 times per week. Research shows such programs can potentially modify risk factors for ACL injury and reduce injury rates in athletes through improved neuromuscular control and technique when landing, cutting, and changing directions suddenly.

1. Prevention and Rehabilitation
for ACL injuries
Aimee.R.Burnett@hitchcock.org

2. Objectives
1. Brief understanding of prevalence and risks of ACL
injuries
2. Understand knee mechanics and importance in
protecting the ACL
3. Familiar with the components of ACL prevention
program

3. What is the ACL anyway?
 ACL – anterior cruciate
ligament
 1 of 4 ligaments in the
knee joint
 Provide stability by
limiting the tibia (lower
leg bone) from moving
forward in relation to the
femur (upper leg bone)
 Limits rotation of the
knee joint

4. ACL injuries/tears
 Contact vs. non-contact
 ~80% non-contact (soccer, basketball, skiing, etc.)
 ~20% contact (football, ice hockey)
 Non-contact – usually with landing, rapidly
stopping, cutting or change in direction
 Altered biomechanical and neuromuscular patterns
 Female athletes have 3.5 x risk of non-contact injury
compared to males

5. Figure 1b. Pivot shift injury.
Sanders T G et al. Radiographics 2000;20:S135-S151
©2000 by Radiological Society of North America

6. Prevalence of ACL injury
 Roughly 250,000 ACL Tears per year in the U.S.
 $20,000+ per reconstruction + rehabilitation
 $5 billion annual cost
 6-12 months away from sport
 High rate of re-injury upon return

7. Bracing
 Following ACL repair and appropriate rehab –
generally not used during sport
 no scientific evidence that a brace is needed after
successful reconstruction and rehab.1
 May use if have ACL tear without surgical
intervention

8. ACL Injury Prevention Program: Basic Components
 Warm–Up (~2 min): increase core temp, increase
heart rate, and circulation throughout the
musculature
 Stretching (~2 min): either dynamic (stretching
while moving) or static (stationary/traditional
stretching)
 Strengthening (~4min): focus on the hip region and
the thigh regions
 Plyometrics (~4 min): jumping, landing, ballistic
movements
 Agility (~4 min): cutting, changing directions

9. ACL Prevention Program
 Goal: decrease the number of ACL tears
 Improve neuromuscular control and train proper movement
patterns
 Gain biomechanical efficiency and accuracy of movement
 Enhance dynamic strength and muscle endurance of the trunk,
hip and knee
 15-minute training session that replaces the
traditional warm-up of practice
 Education for players on strategies to avoid injury
 completed PRIOR TO and DURING sport season
 At least 2-3 times per week x 15 min each session

10. Jumping Technique
 Land:
 on the balls of the feet
 knees flexed (initially ~ 20 deg and then bend to about
40 deg) - Simple cue to land “softly” has been shown to
decrease force at the ACL 3
 chest over the knees
 avoid excessive movement of the knee upon landing
(inward or forward) – keep knee over the middle of
the foot
 Keep hips straight – don’t turn out hips
 Equal weight on the right and left

11. Jumping Technique

12. Basketball injury

13. Knee alignment

14. Why land with knee bent?
 Quad muscles works to extend
the knee region – also pulls the
lower leg bone forward (tibia)
relative to the upper leg bone
(femur)
 ACL prevents this forward
movement of the tibia
 Hamstring muscles work to bend
the knee and pull the tibia
backward (works with the ACL)
 Hamstring allows the muscles to
absorb the force when landing
and supports the ACL
 Landing with knee bend causes
less stress at the ACL and allow
muscles to absorb the force
Femur
femur

15. Strengthening Component
 Balance between the hamstring and quad
muscles
 recommended that the hamstrings be 60 -
80% as strong as the quads
 Work on the hip muscles to stabilize knee
and control knee

16. Plyometrics
 Designed to produce fast, powerful movements, and
improve the functions of the nervous system
 Examples: squat jumps, drop jumps, bounding
 Has been shown to be one of the most effective tools
to reduce non-contact ACL injuries 4

17. Agility
• Cutting, changing directions, changing speed of movement

18. What does research say
 Lim et al. “injury prevention program could
potentially modify the flexibility, strength and
biomechanical properties associated with ACL injury
and lower the athletes risk for injury”
 Female basketball student who had injury prevention 20 min
warm up every practice demo increased strength and flexibility
 Gilchrist et al. studied just under 1500 collegiate
athletes:
 70% reduction in ACL injury with noncontact injury
 40% overall reduction in ACL injury

19. References
1. Dubljanin-Raspopovic E, Bumbasirevic M, Devecerski G, Matanovic D. The effects of functional
knee bracing after anterior cruciate ligament reconstruction. Med Pregl. 2009 Sep-Oct;62(9-
10):483-7.
2. Bien DP. Rationale and implementation of anterior cruciate ligament injury prevention warm-up
programs in female athletes. J Strength Cond Res. 2011 Jan;25(1):271-85.
3. Laughlin WA, Weinhand JT, Kernozek TW, Cobb SC, Keenan KG, O’Connor KM. The effects of
single-leg landing technique on ACL loading. J Biomech. 2011Jul7:44(10):1845-51. Epub 2011 May
10
4. Lim BO, Lee YS, Kim JG, An KO, Yoo J, Kwon YH. Effects of sports injury prevention training on
the biomechanical risk factors of anterior cruciate ligament injury in high school female basketball
players. Am J Sports Med. 2009 Sep;37(9):1728-34. Epub 2009 Jun
5. Gilchrist J, Mandelbaum BR, Melancon H, Ryan GW, Silvers HJ, Griffin LY, Watanabe DS, Dick
RW, Dvorak J. A randomized controlled trial to prevent noncontact anterior cruciate ligament
injury in female collegiate soccer players. Am J Sports Med. 2008 Aug;36(8):1476-83.
6. Willy RW, Davis IS. The Effect of a Hip Strengthening Program on Mechanics During Running and
During a Single Leg Squat. 26. J Orthop Sports Phys Ther. 2011 Jul 12. [Epub ahead of print]
7. Lubahn AJ, Kernozek TW, Tyson TL, Merkitch KW, Reutemann P. Chestnut JM.Hip muscle
activation and knee frontal plane motion during weight bearing therapeutic exercises.Int J Sports
Phys Ther. 2011 Jun;6(2):92-103.
8. R Tyler Hamilton, MS, ATC, Sandra J Shultz, PhD, ATC, CSCS, Randy J Schmitz, PhD, ATC, and
David H Perrin, PhD, ATC, FACSM. Triple-Hop Distance as a Valid Predictor of Lower Limb
Strength and Power. J Athl Train. 2008 Mar-Apr; 43(2): 144–151.