  Anterior cruciate ligament (ACL) reconstruction necessitates months of
rehabilitation, during which a clinician evaluates whether a patient is ready
to return to sports or occupation. Due to their time- and cost-intensive
nature, these screenings to assess progress are unavailable to many. This paper
introduces an automated, markerless, camera-based method for estimating
rehabilitation criteria following ACL reconstruction. To evaluate the
performance of this novel technique, data were collected weekly from 12
subjects as they used a leg press over the course of a 12-week rehabilitation
period. The proposed camera-based method for estimating displacement and force
was compared to encoder and force plate measurements. The leg press
displacement and force values were estimated with 89.7% and 85.3% accuracy,
respectively. These values were then used to calculate lower-limb symmetry and
to track patient progress over time.
