Knee Kinetics in Baseball Hitting and Return to Play after ACL Reconstruction

Abstract

The purpose of this study was to describe the knee kinetics of baseball hitting, develop a tool to predict knee kinetics from easily obtainable measures, and to compare knee kinetics to other exercises along the rehabilitation continuum to determine a timeline for when hitting may resume after ACL reconstruction. Nineteen high school baseball athletes (16.3±0.8 yrs, 180.6±5.7 cm, 78.4±10.8 kg) participated. Participants took ten swings off a tee. Kinetic data were recorded using an electromagnetic tracking system. Data from swings with the top three exit velocities were averaged for analysis. Linear regressions were used to determine if predictors of height, mass, age and exit velocity could predict the following torques: bilateral knee net, extension, internal and external rotation, valgus and varus torque; and anterior force. Backwards regression models revealed independent variables could significantly predict front knee net, internal and external rotation, extension, and varus torque, and anterior force; and back knee net and valgus torque. Based on the kinetics of baseball hitting compared to those of rehabilitation exercises, if the involved knee is the front, we suggest tee hitting may be initiated at 13 weeks after ACL reconstruction. If the involved knee is the back, we suggest tee hitting may initiated at 17 weeks after ACL reconstruction.

Proposed Musculoskeletal Examination of Youth and Adolescent Baseball Players

“…Advancements in return to hitting protocols have been suggested by Giordano et al (35) following ACL reconstruction in 19 high school baseball athletes. Bilateral knee kinetic values were analyzed using knee extension torque, knee internal and external rotation torque, knee varus and valgus torque, and knee anterior force (35). Comparing kinetics of the baseball swing with those of rehabilitation exercises, it is suggested that tee hitting may be initiated at 13 wk postoperatively following ACL reconstruction on the front knee and 17 wk postoperatively on the back knee (35).…”

“…Advancements in return to hitting protocols have been suggested by Giordano et al (35) following ACL reconstruction in 19 high school baseball athletes. Bilateral knee kinetic values were analyzed using knee extension torque, knee internal and external rotation torque, knee varus and valgus torque, and knee anterior force (35).…”

“…A number of studies have looked at factors related to injury in the youth baseball population over the past year ranging in topics from; early sport specialization (ESS) (12)(13)(14)(15)(16), pitch counts (17)(18)(19)(20)(21)(22)(23), prethrowing protocols (24,25), imaging findings (26), to body region-specific inquiries (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43) in search for opportunities to reduce the risk of injury in this population. We will review a wide range of articles and their relevance to injury risk in this population.…”