There is a wide range of low back pain, and low back pain may be concentrated in the center of the spine in conditions such as supraspinous ligament strain and interspinous ligament strain. If it is lumbar muscle pain on both sides of the spine, it may be lumbar muscle strain, or acute lumbar sprain. If it is the whole back, it may be rheumatic low back pain, or lumbar dorsal fasciitis, etc. Patients with low back pain may develop radiating pain in the lower extremities (e.g., lumbar disc herniation). It is characterized by lumbar pain and radiates down the back of the thigh to the leg, sometimes accompanied by limb numbness and limb atrophy. Kidney pain, on the other hand, is narrower in scope and is fixed at the angle between the sides of the spine and the lowermost angle of the posterior border of the thorax, called the renal area. In kidney pain, there will be percussion pain in this area, and the pain of kidney pain may radiate to the anterior side of the thigh root, sometimes accompanied by hematuria or pain in urination or fever, etc.