What is lumbar spinal canal lateral saphenous stenosis? In some clinical cases, there is a preoperative diagnosis of lumbar disc herniation, but intraoperatively there is no protruding disc or only a small protrusion, and the main lesion is lateral stenosis of the spinal canal compressing the nerve roots, which we call lateral saphenous stenosis to distinguish it from main spinal stenosis. Lateral saphenous fossa refers to the narrowing of the spinal canal extending laterally, mainly in the trilobar spinal canal and most typically in the lower two lumbar vertebrae. The lateral saphenous fossa is generally considered to be narrow if the anterior and posterior diameters are less than 3 mm, normal if they are more than 5 mm, and relatively narrow if they are in between. So, why is the lateral saphenous fossa narrowed? Congenital factors can cause lateral saphenous stenosis. The deep lateral saphenous fossa and small anterior-posterior diameter of the trilobar spinal canal are developmentally predisposed to stenosis. Another important factor contributing to stenosis is degeneration. Degeneration of the intervertebral disc with calcification of the fibrous annulus, hyperplasia of the posterior superior edge of the vertebral body, and protrusion into the lateral saphenous fossa from the anterior to the posterior; supra-articular synapse of the inferior vertebrae after disc stenosis; hyperplasia of the isthmus, hypertrophy and calcification of the ligamentum flavum, and protrusion into the lateral saphenous fossa from the posterior; and anterior or posterior slippage of the degenerated vertebral body can contribute to lateral saphenous fossa stenosis. What are the manifestations of lumbar lateral saphenous stenosis and how is it treated? The disease occurs mostly in middle age and above, more men than women, which may be due to the heavy load of men, more cloverleaf-shaped lower lumbar spinal canal, and small preserved gap around the nerve root, which is prone to compression symptoms. Patients generally have a long history of low back pain and low back and leg pain, leg pain is often heavier than those with disc herniation, and exertion or trauma can induce pain or make symptoms significantly worse. Neurogenic intermittent claudication is progressive, and the claudication distance decreases from hundreds of steps to tens of steps, and is relieved after squatting or sitting down to rest. Lower extremity pain radiates along the lumbar or sacral innervation zone. Lateral saphenous stenosis is a mechanical compression of the nerve root by adjacent structures and is not amenable to conservative treatment. Traction is only suitable for those with less severe compression. For diagnosed cases, surgical treatment should be chosen to completely relieve the nerve root compression, and the surgical technique should be improved to avoid unnecessary expansion of decompression, which may affect the stability of the spinal segments.