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