Knee flexor strength and symmetry vary by device, body posit
The objective of this study was to determine whether positioning (seated vs supine), consideration of peak or joint-angle-specific torque or device impact the magnitude of knee flexor strength differences between limbs.

Participants (n=31) who were at 14±4.4 years follow-up for unilateral ACL reconstruction with semitendinosus/gracilis grafts completed the ACL Quality of Life outcome and an assessment including isokinetic concentric knee extensor and flexor strength in seated and supine with peak torque and torque at 60° and 75° knee flexion measured, followed by an eccentric Nordic Hamstring Curl.

--Isokinetic concentric knee flexor torque was reduced in supine relative to seated, on the reconstructed limb against the unaffected, and at higher degrees of knee flexion relative to peak torque.

--Limb symmetry varied by methodology with reduced symmetry in supine T75 against all measures, supine T60 against seated peak torque, and the NordBord was lower than seated peak torque that was not statistically significant.

--Knee extensor peak and Nordic curl eccentric torque were predictors of ACL-QoL score, although a combined model did not improve over Nordic torque alone.

Finally, because impairments are highest in the supine position with torque assessed at 75° knee flexion, limb symmetry cannot be assumed in clinical practice across different evaluation methods for knee flexor strength. During the Nordic hamstring curl, isokinetic knee extensor and eccentric knee flexor torque were predictors of ACL-QoL rating and should be examined alongside patient-reported outcomes for patients undergoing ACL repair with hamstring grafts.