1. Pathological phases:
－－－3 phases according to different pathological stages of nuclear marrow：

i. Before protrusion phase: because of degeneration or injury, nuclear marrow may become fragments or scar-like connective tissue. The deformed annulus fibrosus (AF) becomes thin and soft or shows fissures due to repeated injuries. During this phase, patients feel lower back pain and discomfort.
ii. During Protrusion phase: when pressure in the intervertebral disk (IVD) increases, nuclear marrow ruptures from the weakened point or fissure of the AF. The rupture compresses or stimulates nerve roots and therefore generates radiate pain of lower limps. When cauda equina is compressed, it causes urination and excretion difficulties.
iii. Postrupture phase: for long-term rupture, secondary pathological changes usually take place between nuclear narrow and its surrounding connective tissues, such as calcification of ruptured nuclear marrow, hyperosteogeny of vertebral body rim , injury and degeneration of nerve roots, secondary thickness of ligmentum flavum, hyperosteogeny of articulations zygapophysiales, and secondary narrowness of spinal canal.

2. Pathological Types:
－－－3 types due to different shapes of rupture：

i. knot nuclear marrow : rupture bulges like a knot, smooth surface.
ii.fragment nuclear marrow : rupture looks irregular, broccoli-like , often with surrounding connective tissues.
iii. free nuclear marrow : complete rupture of AF, nuclear marrow fragments pass the ligmentum longitudinale posterius and enter the spinal canal.

３. Five types due to different directions and positions of nuclear marrow rupture:

Anterior rupture, posterior rupture, lateral rupture, peripheral rupture, and rupture into spinal canal. Among them, posterior rupture is the most common one and includes two subtypes: oblique rupture and central rupture.
i. Oblique rupture: ruptured nuclear marrow is located sideways behind the vertebral foramen, exerts pressure on nerve roots and causes radiate pain of lower limbs. According to different relationship between the rupture point and the nerve root, there are 3 subtypes: root-shoulder, root-armpit, and root-front.
ii.　Central rupture: nuclear marrow ruptures back to the center of the vertebral foramen and exerts pressure on nerve roots or cauda equida through its dura mater, then cause damage to them. According to nuclear marrow's positions, there are lateral-central type and central type.

Common locations for PID（ Lumbar Disc Herniation ）:

Over 90% of PID occurs at the last two IVDs. Universally, L4-L5 and L5-S1 are the most frequent sides. It's first because these two disks bear much of the body weight and bending which leads to more degeneration and ruptures. Secondly, L5 and S1 nerves cross over the two IVD below them therefore compress the verves and cause typical symptoms that can be noticed easily.

By studying clinical cases considering the height of the iliac crest line and degeneration of lower IVDs, it's proved that there is a relationship between these two factors. With high iliac crest line, degeneration of L4-L5 is severer, while degeneration of L5-S1 is severed with low iliac crest line.

Besides, most statistics have shown that PID occurs more often on the left side mainly because most people are right-handed when exercising and working. As a result, their right side back muscles have more tension that results in their right side IVDs hold more pressure. The pressure is conducted to the left and may cause rupture of the AF, so the nuclear marrow is squeezed to the left and slips out.

Clinical symptoms of PID （ Lumbar Disc Herniation ） :

⑴ Age: PID is common in people of age 25-50, over 75% of all cases. Even though this is the period of early to middle adulthood, degeneration of the IVD stars already.
⑵ Gender: PID is common in male, because the male ratio of doing social works of is higher than female. The load on the waist vertebrate is also heavier than female's for longer time so that it makes male have more opportunities to have PID.
⑶ Occupation: PID is common, and always happens. It exists in many kind of occupations, but still common in those jobs that need more energy to work. Moreover, for those who always sit to work also have higher ratio to get PID.
⑷ Environment: For those who always live or work in humid and cold places are easier to get LDP. Based on the data, those who work under the mine well for a long time have higher chance to get PID.
⑸ Others: Does PID relate to heredity? Currently, there is no final result yet, butdefinitely those who have hypogenetic nuclear marrow, such as backbone curve, natural backbone crack, etc. will have more chance to get PID. In addition, pregnant females increase their weight rapidly due to the special physical reason so that their muscle and ligaments loose. This is also a dangerous time to get PID.

What are positive pathological signs of lumbar disc herniation?

⑴ Limited movement of spine column: Normal lumbar movement scope should be 90-degree flexion and 20-degree extension, 20~30 - degree lateral flexion and 30–degree rotation for both sides. With disc protrusion, the front part of intervertebral disc will protrude when spine flexes . Posterior intervertebral disc space becomes wider, marrow nuclear of Intervertebral disc moves backward which increases the herniation tension. Then, the marrow nuclear moves upward and pulls the nerve root to cause pain. When waist is extended, the herniation becomes bigger and ligamenta flava tiara extrudes forward so that nerve root is squeezed from front and back sides to cause pain. So the pain limits the movement of spine.
⑵ Tenderness point : When tintervertebral disc protrudes, its paravertebral area has obvious tenderness point and the pain emits towards lower limbs along sciatic nerve distribution area that is also called emission press pain.
⑶ Tendon reflex changing : When intervertebral disc protrudes, knee reflex and achilles tendon reflex weaken, disappear or becomes hyperactive. If L-3 and L-4 intervertebral disc protrude, knee reflex weakens or disappears, eversion and inversion functions of foot becomes weak. If L-4 and L-5 intervertebral disc protrude, knee reflex and achilles tendon reflex exit while posterior tibialis tendon reflex changes, toe extension becomes disable. If L-5 and S-1 intervertebral disc protrude, achilles tendon reflex weaken, disappear or becomes hyperactive, foot eversion strength becomes weak.
⑷ Straight- leg raising test : Having emission pain in lumbar and lateral side of lower leg is positive.
⑸ Lasegue's sign : Lumbar emission pain or muscle spasticity is positive sign.
⑹ Health limb raising test: When health limb is raised straightly and passively, pain in sciatic nerve distribution area of affected limb is positive sign.
⑺ Thigh nerve tension test : When hip joint is positioned in over-extension, pulling emission pain in anterior thigh along thigh nerve distribution area is positive sign.
⑻ Supine and throw abdomen test:When throwing abdomen with or without holding one's breath, or cough, lumbar and lower limb emission pains are positive signs.
⑼ Queckenstedt's test : The examiner presses jugular vein with thumb and first finger for about 1-3 minutes to increase intracanal pressure , pains in lumber and lower limbs are positive signs.
⑽ Flexed neck test :When the neck flexes gradually to let chin touch chest, pains in lumber and lower limbs are positive signs.

Examinations by oneself for lumbar disc herniation
Until now, except for CT and MRI, there is no more simple examination or diagnosis method for lumbar disc herniation. However, mastering following characteristics of illness history can make you know this disease fairly well and provide reliable clue to your doctor when you see him：1 History of waist sprain. 2. The disease occurred suddenly, lumbar pain accompanied by lower limb emission pain. 3. Good-or-bad, slight-or-serious, occurs repetitiously. 4. Commonly, first is lumbar pain and then leg pain. 5.The symptoms aggravate when doing actions that can increase abdominal pressure.

Differentiation diagnosis of lumbar disc herniation
1 Pelvic outlet syndrome:Pelvic outlet syndrome refers to the syndrome that occurs when sciatic nerve goes through pelvic outlet and gets stimulated or pressed. Its clinical manifestation is sciatic nerve trunk stimulation symptom which is an emission pain along sciatic nerve from hip and accompanied by moving, feeling and reflex disorder in other distribution areas. Its onset is quick or slow. Often, the patient has the history of trauma, tired, catching a cold or being affected with damp. Intermittent onset is possible for a long disease course. Commonly, the disease appears in single side. At beginning, dull or sometimes sharp pain, ache heavy feeling could occur in hip. And then, the pain emits toward posterior side of thigh and posterior and lateral side of crus but rarely reaches heel or the bottom of foot. Often, the pain has no clear root limit. Walking can aggravate the pain or cause intermittent limp.
2 Superior clunial nerves entrapment syndrome: Stimulation and entrapment of s uperior clunial nerves going through deep fascia pore can cause a series symptoms. The clinical manifestations are lumbar and sciatic pain that can diffuse to thigh and the back of knee, but crus is rarely involved. There are obvious t enderness points under the border of outer and upper iliac crest of posterior superior iliac spine. Sometimes funicular nodes or small lipoma can be touched. Sciatic muscle spasm is possible. Local medicated blockade can eliminate pain at once.
3 Syndrome of transverse process of third lumbar vertebra:The third lumbar vertebra lies in the middle part of lumbar vertebra with the longest transverse process and big backward extension degree. Several lumbar, back and abdomen muscles and fascia attach on it to form a function hinge and stress center of lumbar vertebra. So, it is easy for the third lumbar vertebra to receive the muscles' and fascia's pulling and get trauma. The posterior part of the tip of transverse process of the third lumbar vertebra is very close to the posterior branch of the second lumbar nerve root. When the lumbar flexes forward or bend to the opposite side, the third lumber vertebra is easy to be pulled and abraded to cause pain and numb etc. in its distribution area. Also, the anterior branch is easy to be involved to cause emission pain. The pain can spread to coax and anterior side of thigh and a few can emit to perineum. The onset of transverse process syndrome of third lumbar vertebra can be slow or quick. The history of trauma is possible.
4 Gluteus insufficiency:Acute gluteus insufficiency can cause muscle spasm and its t enderness point lies in lateral side of posterior superior iliac spine . Local medicated blockade can eliminate pain at once.
5 Interspinous ligament insufficiency: It is one of the common reasons for lumbago which exhibits aches and fatigue in lower lumbar on stooping down, difficult unbending and local pain.
6. Sacroiliac joint insufficiency: Its clinical manifestations are continual local pain, being fear to load, becoming bad when moving and being difficult to turning over.

PID surgery some limitation in:
⑴ Those who have PID for the first time, and they have not yet got any conservative treatment.
⑵ Those who have PID and no obvious nerve damaged symptoms.
⑶ Those who have PID, waist muscle fiber inflammation and rheumatism.
⑷ Older people who have PID and severe hypertrophy rachitis.