The femoral nerve is one of the largest neural structures in the leg. Its branches supply sensation to the upper thigh and control the quadriceps muscle, which is responsible for straightening the knee. Femoral nerve impingement can produce various symptoms. Numbness, tingling and shooting pain into the leg (and sometimes into the groin area) is common.
Erik Dalton Blog
In the early 20th century, sacroiliac joint syndrome (SIJ) was the most common medical diagnosis for low back pain, which resulted in that period being labeled the “Era of the SI Joint.” Any pain emanating from the low back, buttock or adjacent leg usually was branded and treated as SIJ.