Understanding the Mechanics for Prevention of Knee Injuries

Amy E. Goren, PT, DPT

Tibiofemoral JointHinge Joint Movement: Flexion & Extension•Close Packed Position: Nearly Full EXT

– Screw Home Mechanism: 0-20°• Rotation of the Knee Itself

•Open Packed Position: 25° FLEX

Rotation and Alignment of the Knee are Controlled by the Hip and Ankle

The Knee During Gait

http://www.utdallas.edu/atec/midori/Handouts/walkingGraphs.htm

http://www.oandp.org

Rotation of the Knee During Gait• Knee FLEX during Loading Response

– CKC: Screw-Home Mechanism Reverses• Anterior Femoral Glide and Femoral ER

– Tibia IR• Pelvic Rotation of Loading• Subtalar Pronation at Heel Strike

• Knee EXT during Mid-Stance– CKC: Screw-Home Mechanism

• Posterior Femoral Glide and Femoral IR– Tibia ER

• Pelvic Rotation of Stance• Subtalar supination for Toe-Off

Reaction from the GroundMovement Up the Kinetic Chain•At Heel Strike: Lateral calcaneous everts

– causing Subtalar pronation

•Subtalar Pronation – causes Tib-Fib Pronation (IR and ADD)

•Attributes to increased Knee Valgus•Which continues up the chain to the Hips

Hip & Core Control PronationNeed for appropriate Recip- and Co- CON and ECC

contractions of the whole LE •Hip should decelerate the femur

– Decrease knee valgus moment

•Eccentric control for deceleration of gravity & forces going to the ground

– Decrease Pronation

Muscles to Focus On:Glut Max, Glut Med, Hamstring, Core (TA)

Image: https://www.pinterest.com/pin/280419514273905287/

The Hip and Patellofemoral PainSouze RB, Powers CM7. January 2009

– Controlled Laboratory Study using cross-sectional design

•Hip Kinematics & Activity Level of Ms.– Running, Drop Jump, Step Down

•Strength: Isometric torque productionWith all activities Pt’s with PFP had:

Greater peak hip IRDiminished hip torque production

14% Less Hip ABD and 17% Less Hip EXT strength

Significantly greater glut max recruitment

Gluteal Muscle Activity & PFPSBarton, CJ et al1. February 2013.

– A Systematic Review

•Ten case-control studies: Gluteal EMG with PFPS•Gluteus Medius activity delayed & shorter duration

– Mod-Strong Evidence: During Stair Negotiation– Limited Evidence: During running

•Gluteus Maximus activity increased – Limited Evidence: During stair descent

“Delayed and shorter duration of Glut. Med. EMG may indicate impaired ability to control frontal & transverse

plane hip motion.”

Exercise for PFPSClijen R. et al2. December 2014

– Systematic Review and Meta-Analysis

•15 studies, 748 Participants•Exercise Therapy

– Strong pain-reducing effects– Decreases activity limitations & participation

restrictions

Which exercise is best at reducing pain and limitations?

Effects of Neuromuscular Warm UpLaBella C, et al. 5 November 2011

– Cluster Randomized Controlled Trial

•90 Coaches and 1492 Athletes•20min NM vs Usual Warm Up

– Intervention coaches used prescribed warm-up in 1425 of 1773 practices (80.4%)

•Significant Results!

“Coach-led neuromuscular warm-up REDUCES noncontact LE injuries…”

LaBella5 Results

Injury Intervention Control P value

Gradual-Onset LE Injury

0.43 1.22 <.01

Acute-Onset NonContact LE

Injury

0.71 1.61 <.01

Noncontact Ankle Sprain

0.25 0.74 = .01

LE Injuries Treated Surgically

0 17 =.04

Rate per 1000 Athletic ExperiencesTotal of 28,023 Intervention AEs & 22,925 Control AEs

LaBella5 Results

Injury Rate 95% CI

Acute-Onset NonContact LE

Injury

0. 33 0.17-0.61

Noncontact Ankle Sprain

0.38 0.15-0.98

Noncontact Knee Spains

0.30 0.10-0.86

Noncontact ACL lnjuries

0.2 0.04-0.95

Regression Analysis Showed Significant Incidence Rate Ratios

Mechanics Screen• Single Leg Hop & Hold (SLH) for Distance

– Dominant Leg vs. Non-Dominant Leg• 3 Trails and Measured in cm• Symmetry Index

– Mean DL/Mean NDL x100 = ___%

• Hands behind back?• Able to hold landing for 2-3seconds?• Limb Symmetry ≥ 85% ?

Mechanics Screen• Drop Vertical Jump (DVJ) From 18”

– Do both feet hit the ground at the same time on initial contact?

– Pronation of the feet on initial contact? – Evidence of increased (M-L) knee motion during initial

contact? – Evidence of increased (M-L) knee motion during the

final landing? – Additional Comments or Observations?

Mechanics Screen• Single Leg Squat (SLS)

– Pronation or Supination of the foot?– Hip Internal Rotation or External Rotation?– Knee Valgus or Varus?– Able to maintain balance?– Able to perform a set of 10 reps?

What we need to incorporate• Dynamic Warm Up: At least 10-15min in length• Balance Activities• Tri-planar Exercises

– Hip Strength and Coordination

• Hops: Uni- and Bilateral• Jump Landing Training• Sport Specific Drills

References1. Barton CJ, Lack S, Malliaras P, Morrissey D. Gluteal muscle activity and patellofemoral pain

syndrome: a systematic review. JOSPT. 2013. 47: 207-214. doi: 10.1136/bjsports-2012-0909532. Clijsen R, Fuchs J, Taeymans J. Effectiveness of Exercise Therapy in Treatment of Patients With

Patellofemoral Pain Syndrome: Systematic Review and Meta-Analysis. PHYS THER. 2014; 94: 1697-1708

3. Garrison C. The Hip and Knee Complex. Therapy Network Seminars. October 17-18, 2009.4. Kim HY, et al. Srew Home Movement of the Tibiofemoral Joint during Normal Gait: Three-

Dimensional Analysis. Clinics in Orthopedic Surgery. 2015; 7: 303-309.5. LaBella CR, Huxford MR, et al. Effect of Neuromuscular Warm-Up on Injuries in Female Soccer &

Basketball Athletes in Urban Public Schools: A Cluster Randomized Controlled Trial. ARCH PEDIATR ADOLESC MED. 2011. 165, 1033-1040

6. McWilliams K. Evidence-Based Sports Enhancement Programs: From ACL Injury Prevention to Speed and Agility Coaching. Cross Country Education. July 23-25, 2015.

7. Souza RB, Powers CM. Differences in Hip Kinematics, Muscle Strength, and Muscle Activation Between Subjects With and Without Patellofemoral Pain. JOSPT. 2009. 39:12-19

ACL RehabilitationAmy E. Goren, PT, DPT

ACL RehabilitationNo less than 6 month period•ROM & Flexibility•Muscular Strength & Endurance•Gait Retraining•Neuromuscular & Proprioception•Return to Sport

Always Follow Protocol Provided by Pt.’s Surgeon

0-2 WeeksPt. education for weight-bearing status

Decrease pain & swellingIncrease ROM & restore full EXT:

Maintain hamstring and calf flexibility

Quadriceps activation: Ex. Isometric and Quad/Ham co-contraction

Proprioceptive/balance re-ed:Ex. SLS, Weight Shift and Wobble c Support

Gait:2-1 Axillary Crutches maintaining normal walking pattern

Maintain cardiovascular fitness

3-6 WeeksAchieve near to full ROM

Full Bike, Prone Knee Stretch, Standing Stretches

Progress flexibility and strengthEx. Fwd/Lat Step Ups 2-4”

Strengthen bilaterallyEx. Wall Squats 40-60°

Proprioception progressionsEx. Decrease Support

Gait: Full WBMaintain cardiovascular fitness

May Start elliptical or Stair Master-No Hip Hiking

6-9 WeeksFull pain free ROM

Functional quad strengthEx. ECC Lat Step Downs 2-6” & Static Lunge ¼ - ½ Range

Isokinetic quad strengthening ONLY if full ROM, no swelling, adequate control, no meniscal or PFJ

pathologyAddress quad deficits

High/Low Velocity, CON/ECC, 0-95°Strengthening LE without pain

Ex. Full Wall SquatAdvance proprioception

Ex. BOSU Marches & Squats 60-90°Increase cardiovascular fitness

Ex. Swim- Pool Jogging & Flutter Kick ONLY

9-12 WeeksContinue with flexibility

Mobilizations PRN

Quad strength progressionEx. Static LungeDynamicWalking Lunge

Address hamstring deficitsHigh Speed, ECC 95-60°

Continue lower chain CON/ECC strengthening of quad and hams: 60-95° and Full ROM

Progress proprioceptionEx. Catch & Throw on Various Surfaces

Sport specific cardiovascular fitnessEx. Treadmill +/- Incline Quick Walk

12-16 WeeksContinue flexibility & strengthening

Sport Specific quad & ham strengtheningCON and ECC Ham & Quad- Full and Inner Range

Sport Specific proprioception trainingEx. Ladder Drills, 2 Legged Jumping

Sport Specific cardiovascular fitnessEx. Jogging: Straight on flat ground NO cutting or downhill

STOP: If swelling, loss of motion or patellofemoral pain

Initiate 2 Legged Hop Tests: Hop for Distance, 6m Timed Hop, Triple Hop, Crossover Hop

16-20 WeeksSport specific quad, ham and lower chain strengthening

Ex. Plyometric and Agility Training with 2 1 LE progressions*Watch Landing Mechanics*

Proprioception trainingEx. Maintaining balance for 5sec on Landing from Hops

Sport specific cardiovascular trainingEx. Running (Normal Painfree Stride) & Jogging c Turns

Hop Test: Single Hop, 6m timed hop, triple hop, crossover hop

20-24 WeeksAdequate Fitness, Strength, Power, Agility and

Neuromuscular ControlMinimize Compensations

Back to sport practice for upper skillsReturn to sport skills on own at practice

Minimal risk of re-InjuryGradual return over 6-9months- NO PAIN or SWELLING

All Hop Tests within 15% of uninvolved side

Rehab. Compliance Improves OutcomesHan F, et al. 3 2015

– Cohort Study, Level 3

•93 Recreational Athletes prescribed PT for 20 visits Post OP•Outcome Measures: Knee Injury and OA Outcomes Score (KOOS), Lysholm Scale and Short-Form Health Survey (SF-36)

– Pre and 1-yr Post OP

•Compliance: Fully >15, Moderate 6-15, Non <6 sessions

Greater compliance correlates with greater chance of return to sport and improved knee function

OKC vs CKC ExercisesUcar et al.2 2014•58 Pts into Group 1: CKC and Group 2: OKC •Outcome Measures: Pain VAS, Thigh Circumference, Knee FLEX ROM and Lysholm Scale

– Pre-Op, 3month and 6months

•Values of CKC group were statistically significantly high between groups in Lysholm and ROM scores

“CKC exercises are more effective than OKC at providing mobilization & enabling a quicker return to daily and sporting

activities”

Neuromuscular vs. Strength TrainingRisberg MA, et al4, 2007

– Randomized Clinical Trial

•NT Protocol vs. ST Protocol•Measurement taken at 3 & 6months Post-OP

– Primary: Cincinnati Knee Score– Secondary: VAS for pain and function, 36-Item Short Form Health

survey, Hop Tests, Isokinetic Muscle Strength, Proprioception, and Static and Dynamic Balance Tests

NT significantly better at 6month: Cincinnati Knee Score & VAS Function

Neuromuscular Training Program

Strengthen Training Protocol

Common CompensationsErnst GP, et al1, 2000•Scoring within normal on SL hop test but quad weakness?•Evaluated LE kinetics during

– SL Vertical Jump (VJ)– Lateral Step Ups (LSU)

•Examined hip, knee and ankle EXT moments– Motion analysis and Force platform system

•Matched during LSU, VJ take-off and landing•No difference in sum EXT moment

HIP and ANKLE EXT COMPENSATIONS

References1. Ernst GP, et al. Lower- Extremity Compensations Following Anterior Cruciate Ligament

Reconstruction. PHYS THER. 2000; 80: 251-260 2. Fowler Kennedy Sport Medicine Clinic.. Physiotherapy ACL Protocol. Revised March

2009.3. Han F, et al. Increased Compliance With Supervised Rehabilitation Improves

Functional Outcome and Return to Sport After Anterior Cruciate Ligament Reconstruction in Recreational Athletes. OJSM. 2015; 3(12). doi: 10.1177/2325967115620770

4. Risberg MA, Holm I, Myklebust G, Engebretson. Neuromuscular Training Versus Strength Training During First 6 Months After Anterior Crucuiate Ligament Reconstruction: A Randomized Clinical Trail. PHYS THER. 2007; 87: 737-750. doi: 10.2522/ptj.20060041

5. Ucar M, et al. Evaluation of Open and Closed Kinetic Chain Exercises in Rehabilitation Following Anterior Cruciate Ligament Reconstrunction. J.PHYS. THER. SCI. 2014; 26: 1875-1878. doi: 10.1589/jpts.26.1875