What Causes Weakness In The Legs Upon Climbing Stairs?

My post decompression and laminectomy surgery results show I still have flattening of the ventral thecal sac at the L4/5 level along with moderate bilateral neuroforaminal stenosis and mild bilateral recess stenosis. My right leg show weakness climbing stairs, up/down uneven surfaces, walking. I have a limp caused bio-mechanically, not from pain. I also have sharp pains and aches into both thighs, quadriceps. General practitioner, neurologist and neurosurgeon all shrug as to the cause of the limp. Could this be some kind of impingement on the femoral nerve?