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.
Key words
ACL rehabilitation protocol - knee biomechanics - clinical measures - rehabilitation
protocols - return to play
