I. Determine the site (a) lumbar spinal canal lesions 1. lumbar forward flexion and back extension functional activities. The forward flexion activity of the lumbar region is firstly completed 50% by hip flexion, and only secondly is 50% really completed by the lumbar spine itself. About 75% of the lumbar forward flexion activity depends mainly on the function between L.5-S.1 (the remaining 25% function is completed by L2-5). When the L.5-S.1 disc is herniated or the lumbosacral or sacrospinous muscles are damaged it will significantly limit the forward flexion activity. In contrast, when the lumbar posterior extension activity is done mainly by the lumbar 2-5 segment. The above conditions make the L.5-S.1 segment less affected, and thus the limitation of lumbar posterior extension activity with neurological symptoms should be considered as lesions of L.3-4/L.4-5 segments. Similarly, the motor segment affecting the sitting work should be the L.5-S.1 site. 2, pressure pain in the paraspinal or median area of the lumbar spine can suggest segmental damage in the spinal canal. Interspinous pressure pain with paraspinous interlaminar pressure pain and lower extremity radicular pain indicates a central lateral disc herniation; if only interspinous pressure pain or paraspinous interlaminar pressure pain and lower extremity radicular pain are present, a central or lateral disc herniation should be considered. Of course, the site of pressure pain is of great value in differentiating damage to different segments of the spine, especially spinal tapping pain is meaningful for the detection of intraspinal occupying lesions and can be used as a screening method before CT scan/MRI examination. 3.Neural localization signs. It has a high diagnostic value, but the clinical manifestation is late. (1) Sensory loss or disappearance. The distribution of sensory nerves in the lumbar back is mainly innervated by the posterior branch of the spinal nerve; the distribution of sensory fibers in the spinal canal is innervated by the sinus nerve emanating from its posterior branch, and the limbs are innervated by the sensory branches emanating from the plexus composed of the anterior branch of the spinal nerve. Therefore, sensory deficits in the corresponding cortical areas innervated by the affected nerve roots can be used as a reference for the diagnosis and localization of lumbar spinal canal lesions. However, the prerequisite is that the two lesions within and outside the spinal canal are first distinguished. This is because compression of the sciatic nerve trunk and its branches by spasm or degenerative contracture of the soft tissues of the lumbopelvic lesion can also produce hyperalgesia or loss of sensation in the innervated dermatomes in the same way as compression of the lumbar nerve root itself. The sciatica and hyperalgesia or hyperalgesia of the lateral calf seen clinically are signs common to both intradural and extradural damage. (1) Lateral thigh dermatomal area. Nerve branch from the lumbar plexus (L.2, 3). (ii) Anterior medial calf cortex. From the lumbar plexus (L.4) nerve branch. (iii) Posterior lateral thigh, lateral calf cortex, lateral ankle, dorsal foot and medial three toe cortex. From the sacral plexus (L.5-S.1) nerve branch. ④Posterior thigh, posterior calf, plantar or lateral edge of the foot and the lateral two toe skin areas. Nerve branches from the sacral plexus (L.5-S.1, 2). (2) Muscle weakness. The muscle weakness at different sites reflects the involved nerve segments. For example, weakened quadriceps muscle reflects segmental involvement of L.2, 3, and 4 (knee extension ↓); weakened anterior tibialis muscle reflects segmental involvement of L.4 (dorsiflexion ↓); weakened extensor hallucis longus muscle reflects segmental involvement of L.5 (bunion ↓); weakened plantarflexor and flexor hallucis longus muscle reflects segmental involvement of S.1 (plantarflexion ↓); however, it should be noted that muscle weakness or atrophy is also a common sign of lesions within and outside the spinal canal. Clinically, a single-footed trunk support movement (kinematic stance) may indicate S.1 segment involvement or not. (3) Reflex disorders. The tendon reflexes of the lower extremities have a more accurate localization. In intraspinal lesions, the involved nerve segment can be identified. Decreased or absent knee tendon reflexes reflect lesions of L.3 and 4 segments. Decreased or absent Achilles tendon reflexes reflect lesions in the S.1 segment. If pathological reflexes such as Babinski’s sign appear, the intradural lesion should be considered as a vertebral fasciculus sign in the cervicothoracic spine, which is mostly caused by spinal cord damage lesions. 4. prone knee and hip flexion and extension test. l.4-5 disc herniation stimulates compression of L.5 nerve root, this test can be positive. However, if the L.5-S.1 disc herniation stimulates and compresses the S.1 nerve root, this test will not lead to radiating pain in the lower limbs, so it can distinguish the nerve damage in the L.4-5 segment from that in the L.5-S1 segment. (2) Soft tissue damage outside the lumbar spinal canal 1. pressure points and involvement pain (1) pressure points in the lumbar hip. Upper gluteal cutaneous nerve pressure points; pressure points at the inferior exit of the sciatic nerve pear-shaped muscle; pressure points at the superior exit of the superior gluteal nerve pear-shaped muscle; pressure points at the inferior exit of the inferior gluteal nerve pear-shaped muscle; pressure points at the slapping fossa of the tibial nerve; pressure points at the fat pad under the pin; pressure points below the inner ankle (posterior tibial tendon and tendon sheath); pressure points below the outer ankle (peroneal long and short tendons and tendon sheath). (2) Involvement pain. Soft tissue damage in the area innervated by the sinus nerve or the posterior branch of the spinal nerve may produce a discharge pain in the lower extremity similar to that of spinal nerve root involvement. Usually the path of release pain is vague and not necessarily distant, but in rare cases it can reach the end of the limb. 2. Functional examination. It can confirm the pressure pain point and help localize the pain. (1) Straight leg elevation test: sciatic nerve tension; (2) Flexion knee and hip split test: adductor muscle group; (3) Hip abduction test: gluteus medius; (4) Iliotibial bundle tension test; (5) Hip internal rotation test: pear muscle; (6) Sacroiliac joint test: “4” test, Gonzalez test, Avery test; (7) Bin lower Fat pad squeeze sign; (8) McDonald’s test: meniscus; (9) drawer test: knee cruciate ligament; (10) femoral nerve tension test. Second, the nature of the distinction. The nature of the lesion can be clarified based on clinical features, imaging and laboratory diagnosis. (1) Tumors: neurofibroma, nerve sheath tumor, nerve root cyst, dermatomal cyst, ventricular meningioma, metastatic carcinoma (liver, kidney, prostate, ovary), spinal cord glioblastoma, neuroblastoma, arteriovenous tumor, etc. (2) Malformation (sacralization, lumbarization, spina bifida) (3) Spinal cord cavernous disease, multiple sclerosis. 2.Common disorders. (1) Lumbar disc herniation (central type, lateral paracentral type, lateral type, extreme lateral type, anterior type). (2) Thoracolumbar spinal stenosis (congenital, developmental, degenerative, traumatic, medical, mixed). (3) Lumbar spinal slippage (leading to secondary spinal stenosis) (4) Soft tissue damage (hypertrophy of the ligamentum flavum, calcification of the posterior longitudinal ligament, degenerative contracture of fatty connective tissue, etc.) (B) Extra-vertebral canal lesions. (1) Tumor or atopic lesion (1) spinal tumor, tuberculosis, eosinophilic granuloma. (2) sequelae of spinal injury: crush fracture, splinter fracture, fracture dislocation. (2) Rheumatoid arthropathy. Rheumatoid arthritis, ankylosing spondylitis, osteoarthritis, Liet’s syndrome, systemic lupus erythematosus, gouty arthritis, dermatomyositis and reactive arthritis, sacroiliac joint disorders, ischemic necrosis of the femoral head, etc. 3.Organ disorders and systemic disorders. Hepatobiliary and digestive system, genitourinary disorders, gynecological disorders, endocrine disorders (hypothyroidism, diabetes mellitus, aldosteronism). 4. Vascular disorders. Thrombo-occlusive vasculitis, thrombotic deep phlebitis, common iliac artery or external iliac artery thrombosis. 5, soft tissue damage (including myofascial pain syndrome, fibromyalgia syndrome). Roughly divided into lumbar muscle group, gluteal muscle group, internal femoral retractor group, ventral muscle group, slapping cord muscle group, medial and lateral heads of gastrocnemius, submental fat pad, peroneal long and short muscles, posterior tibial muscle group, tarsal sinus soft tissue and metatarsal tendon membrane and other parts of the injury aseptic inflammatory reaction. 6, infectious. Herpes zoster, lymphangitis.