--the femoral nerve wouldn't be considered a peripheral nerve; it does arise from the L2/L3/L4 roots in the lumbar plexus, so it's not spinal, but one step removed.

Entrapment syndromes of the femoral nerve are actually fairly common among diabetics and people with autoimmune vasculitic/connective tissue disorders--there are a lot of anatomical points at which pressure can be applied and disrupt function:

http://emedicine.medscape.com/article/1234809-overview

Considering the several branches the femoral nerve splits into, symptoms down the thigh are often difficult to isolate to a particular part of the nerve, and a lot of NCV/EMG testing may be needed.