Lateral knee numbness may be caused by knee joint degeneration, sciatica, lumbar disc herniation, lateral femoral dermatitis and other diseases. 1. Knee joint degeneration: middle-aged and old-aged patients may experience numbness on the outside of the knee due to knee joint degeneration and calcium loss. 2. Sciatica: trauma, nerve compression and other causes lead to sciatica, which causes the nerve innervating the lateral thigh to be compressed, resulting in numbness due to sensory impairment. 3. Lumbar disc herniation: The herniated disc and other tissues compress the nerve root, resulting in sensory disturbances on the outside of the knee of the lower limb. 4. Lateral femoral dermal neuritis: dermal neuritis is caused by autoimmune and other factors, resulting in abnormal nerve conduction and symptoms. When the numbness on the outside of the knee, it is recommended to go to the hospital in time, under the guidance of the doctor to further identify the cause of the disease, and standardized treatment under the guidance of the doctor.