Practical Review of Knee Injury Prevention Exercise for Young Athletes
mag. Stef Harley, univ. dipl. FTH
Ali Nassib, dipl. FTH
Maj 2014, ZVD Center za medicino športa, Ljubljana
Strokovni posvet: KAKO DO ZDRAVEGA ŠPORTNIKA V ZRELIH LETIH? Preprečevanje in uspešno zdravljenje poškodb kolena
Knee Injuries in Young Athletes
• 63% sports injuries are joint sprains
• Majority occur in knee
• ACL injuries most common in all ages
• Highest incidence in pivoting sports; ≤ 3.7/1,000h
• Women at 6x higher risk
Prevention is High Priority
ACL injury may lead to:• Concomittent meniscus and cartilage damage• Acute & chronic muscle deconditioning• Knee instability unavoidable
• Future career questionable !
• 5% population with OA have knee injury history
• 50% develop OA ≥10years• 41% more recovery time
Injury mechanisms• 70-84% non-contact situation
• Landing, cutting, decelaration & changes in direction High knee internal extension torque Dynamic valgus rotation BW over injured leg Plantar surface of foot fixed
• Inability to adequately absord GRF
Risk factors & prevention
• External and internal; environmental, anatomical, hormonal , neuromuscular and biomechanical conditions
• Modifiable and non-modifiable
• Prevention strategy: In-depth analysis external &
internal RF Modifiable or non-modifiable? Modify RF through target training
intervention Understand impact non-
modifiable RF
Landing strategy & posture• Increase GRF dampening capabilities
• Increase plantar flexion• Reduce hip flexion• Control knee valgus• Control Q/H power ratios• Stimulate hamstring reflex arc
• Athletes physical capabilities?
CORE stability• Uncontrolled hip ADD and IR with knee ABD
increases risk
• Adolescent athletes; decreased hip & trunk stability Hip and trunk weakness; Excessive movement in frontal and transverse planes; Leads to LE valgus loading
• Strenghtening• Hip ER and ABD• Trunk stabilizers
• High peak force development• Plyometrics – increases efficacy stretch–shortening cycle• Stimulate feed-forward mechanisms - proper technique
Hamstring activation
• Increased HS flexibility slows muscle activation;
• Greater delay in Q/H co-contraction;
• Less functional knee stability;
• HS activation exercises increase functional stability
ACL injury prevention programs• No consensus• Clear progressions• Adressing multiple components yields better results
Decreasing GRF Decreasing varus/valgus moments Increase muscle activation and strength in CORE, hip and
trunk Train feed-forward mechanisms; awareness and in-game
decision making Plyometrics Pre-season combined with in-season maintenance
• Duration, pre-season; 6-8 weeks, 2-3/week• Fatigue?• Compliance?
Common Components
• Proper landing technique
• Engaging knee and hip flexion during landing and lateral movement
• Avoid excessive knee valgus during landing
• Increase HS, hip ER and ABD strength and activation
• Proper deceleration techniques
• Agility skills
• Dynamic balance training
Proper landing technique
Knee & hip flexion during landing
Avoiding knee valgus
HS, hip ER & ABD strength and activation
Deceleration and agility
Wilderman DR, Ross SE, Padua DA. Thight muscle activity, knee motion, and impact force during side-step pivoting in agility-trained female basketball players. Journal of Athletic Training 2009;44(1):14-25
Dynamic balance
Conclusions
• Preventing ACL injury in young athletes makes sense
• Structured preventive exercise has positive effect
• Know and understand risk factors for the target group
• Build compliance – get everyone involved; use performance measures
• Pre-season and maintenance