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

Anterior Cruciate Ligament Reconstruction Csintalan et al., 2008

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

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 0 50 100 150 200

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

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)

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

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 4 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)

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

Data Reduction You can edit this and paste as new picture (for resizing) 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

Peak Contact Force Average Loading Rate medial tibiofemoral joint patellofemoral joint

Impulse Per Step Impulse Per Km medial tibiofemoral joint patellofemoral joint

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

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

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

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

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