1. Collin D. Bowersock, Paul DeVita, Richard W. Willy, John D. Willson
RUNNING MODIFICATION’S EFFECT ON KNEE JOINT LOADING CHARACTERISTICS AMONG INDIVIDUALS WITH ACL RECONSTRUCTION
Collin D. Bowersock, Paul DeVita, Richard W. Willy, John D. Willson

2. Anterior Cruciate Ligament Reconstruction
Csintalan et al., 2008

3. ACLR and risk for Knee Osteoarthritis
ACL injury greatly increases the likelihood of knee OA later in life regardless of reconstructive surgery (Culvenor et al., 2014)
Culvenor et al. 2013
Roos 2005

4. Variables Associated With OA Progression
Peak Contact Force
Miyazaki et al., 2002
Sharma, 1998
Kumar et al., 2014
Joint Impulse
Bennell et al., 2011
Maly et al., 2013
Loading Rate
Ewers et al., 2001
Mundermann et al., 2005

5. Patellofemoral joint force (BW)
Shorter Step Length
In the healthy population, a decrease in step length reduces patellofemoral and medial tibiofemoral joint force
Medial tibiofemoral joint force (BW)
Patellofemoral joint force (BW)
Time (ms)
Time (ms)
Willson, 2014
Bowersock et al., in review

6. Running Biomechanics After ACL Injury
Decreased joint moment and joint excursion are seen post ACL injury (DeVita et al., 1992; Noehren et al., 2013; Lewek et al., 2001)

7. Purpose
Test for changes in medial compartment tibiofemoral joint and patellofemoral joint kinetics while individuals with a history of ACLR run with shortened step lengths.
Hypothesis
A 5% and 10% reduction in step length will reduce medial compartment tibiofemoral and patellofemoral peak joint contact force, force*time impulse per step, impulse per kilometer, and average loading rate

8. 16 Individuals (ongoing study)
Age (years)
Time from surgery (months)
Sex
Activity level (Tegner)
KOOS (S/R) 22 50
7 F, 9 M
6.7 87
BPTB Hamstring 8 Allograph 8
Collection
Marker data was collected at 200 Hz (Qualysis™)
Force data was collected at 1000 Hz using an instrumented treadmill (Bertec™)
Data was processed using real time acquisition software (Motion Monitor)

9. Running Protocol Preferred speed and cadence Randomized
5% reduction in step length
10% reduction in step length

10. Data Reduction
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Medial TFJ and PFJ contact forces was estimated using a biomechanical model (DeVita & Hortobagyi, 2001)
Inputs derived using inverse dynamics and measured joint kinematics
Medial compartment force (Schipplein & Andriacchi, 1991)
Variables of interest:
PFJ, TFJ, and medial TFJ peak force, impulse per step, impulse per km and average vertical loading rate.
Repeated measures ANOVA (alpha =.05)
25% knee joint width
Ext Kadd Mom

11. Peak Contact Force Average Loading Rate medial tibiofemoral joint
patellofemoral joint

12. Impulse Per Step Impulse Per Km medial tibiofemoral joint
patellofemoral joint

13. Discussion
A shortened step length significantly reduced peak force, impulse per step, and impulse per km for the PFJ and mTFJ
Demonstrates that joints kinetics can be further decreased
Diminishing benefits beyond 5%
These reductions may promote increased tolerance for running after ACL reconstruction
Decreased chondrocyte lesions, depth of lesions (Horisberger et al., 2013)
Benefits of active lifestyle
Moderate exercise post ACL injury has shown to exhibit chodroprotective effects compared to intense and sedentary activity (Galois et al., 2004)
Demonstrates the effectiveness of a shortened step lengths ability to decrease joint kinetics
Future studies may investigate the modifications ability to preserve knee joint cartilage over time

14. Acknowledgments Human Motion Analysis Lab Michael Baggaley, MS
Chelsea Hollingsworth, SPT
Jennifer Warren, SPT
Amir Sanii, SPT
Justin Meekins, SPT

16. Exercise and Joint Health
After ACL injury, benefits become dose dependent
Mankin’s Score of cartilage health
Structure
Cellularity
Staining
Thickness of chondrocyte layer
Bone remodeling
This score ranged from 0 to 15 according to structure, cellularity, toluidine blue staining, thickness of hypertrophic chondrocyte layer, bone remodelling and osteolysis
Galois et al., 2004

17. Exercise Modalities Surgery
Preinjury participation in yes/no [%yes] /20 (80)
Basketball, Soccer, Football
Running, Swimming, Cycling
Soccer, Basketball, Football
Grindem et al., 2014

18. 2.5
Healthy
1.5
ACLR
Knee extension moment (Nm / kg*m)
0.5
-0.5
-1.5 50
100
% Stance