I wholeheartedly agree that in the majority of cases the SLR as an exercise is pointless (e.g. in the case of ACL post-op) and the regaining of quadriceps function can be achieved much more efficiently with closed kinetic chain/functional positional/cycling/pool exercises etc etc; however this does not mean that it doesn't have a place in the rehab of some patients and conditions.

Sometimes physio's strive to be too original and innovative with exercise prescription and the simplest exercises can often get the fastest results (yes that includes walking, cycling etc). I think that if a person cannot actively complete a SLR (as an assessment) there is a major flaw in the quads mechanism and hence lower limb kinetic chain (even though its not a functional assessment)- if we consider specificity of training then perhaps the SLR as an exercise may be a means of regaining this quickly and effectively - perhaps faster than certain closed chain exercises despite being more functional.

In my experience I only use the SLR where there is an obvious post-op motor recruitment dysfunction (not weakness due to atrophy) and the patient is strict NWB and has restricted ROM (e.g. complicated patella dislocation). But again, as soon as the patient can complete the SLR to the same degree as the contralateral leg then it is discarded immediately as I don't think it offers any functional strengthening.

However getting back to the original post - using SLR as an exercise post ACL although not being harmful (the graft if incredibly strong initially) may not be the most effective way of restoring quads recruitment and promoting progression in ROM - WB or closed chain exercises such as cycling/walking/fitball extensions etc are much more indicated. In saying this, if after 2 weeks (make that 1 week) of this approach the patient still cannot perform an active SLR to the degree of the contralateral leg then maybe its worth doing - just don't tell other physio's as you may be excommunicated