Disc Prolapse

DISC PROLAPSE

PRESENTED BY

VYOM GYANPURIM.P.T. (Ortho)

INTERVERTEBRAL DISC

STRUCTURE A central nucleus pulposus

Surrounded by peripheral annulus fibrosus

Two layers of cartilage which cover top and bottom aspect of each disc called a vertebral end plate

Its separate the disc from the adjacent vertebral body

NUCLEUS PULPOSUS

It is semi fluid mass of mucoid material seems like a tooth paste

It consist of few cartilage cells and irregular arranged collagen fibers

The fluid nature of nucleus pulposus allowed it to be deformed under pressure

The nucleus attempt to deformed and will there by transmit the applied pressure in all direction

ANNULUS FIBROSUS The annulus fibrosus consist

of collagen fibers.

The collagen fibers are arranged in between 10 to 20 sheets called lamellae.

These are arranged in concentric rings that surround the nucleus pulposus.

They are thick in anterior and lateral portion of the annulus but posteriorly they are finer and more tightly packed.

The collagen fibers lie parellel to each other.

VERTEBRAL END PLATES Each vertebral end plate

is a layer of cartiladge about 0.6-1 mm thick.

Covers the area on the vertebral area encircled by the ring apophysis.

Nucleus pulposus is entirely covered but annulus fibrosus is only 66% covered by the end plates.

PROLAPSE

The term prolapsed disc means the protrusion or extrusion of the nucleus pulposus through a rent in the annulus fibrosus.

It has a four stages

Bulging

Protrusion

Extrusion

sequestration

CAUSES Heavy manual labour

Repetitive lifting and twisting

Postural stress

Monotonous work

Lack of personal control on work

Poor physical fitness

Poor and inadequate strength of the trunk

Smoking

Aging process

Mechanical breakdown & loss of nutritional pathways

MECHANISM It only occurs if the disc has deteriorated as

a result of repeated microtraumas and if the annulus fibres have started to degenerate

Disc prolapse usually follows lifting of weight with the trunk flexed forward.

Disc prolapse occurs in three stages

First stage

Trunk flexion flattens the disc anteriorly and open out the intervertebral space posteriorly

Second stage

As soon as the weight is lifted the increased axial compression force crushes the whole disc and violently drives the nuclear substance posteriorly until it reaches the deep surface of PLL.

Third stage

With the trunk nearly straight , the path taken by the herniating mass is the closed by the pressure of vertebral plateaus and the hernia remains trapped under the posterior longitudinal ligament.

Prolapse occurs in two manners also

Sudden disc prolapse

Gradual disc prolapse

PATHOLOGY

Nucleus degeneration Degenerative changes occur disc before

displacement of the nuclear material.

These changes are :-

o Softening of the nucleus and its fragmentation

o Weakening and the disintegration of the posterior part of the annulus

Nucleus displacementThe nucleus is under positive

pressure at all times

When the annulus becomes weak, either because a small area of entire thickness has disintegrated spontaneously or because of injury, The nucleus tends to bulge out.

Stage of fibrosisThis is the stage of repair.

This begins alongside of degeneration. the residual nucleus pulposus become fibrosed.

The extruded nucleus pulposus becomes flattened,fibrosed and finally undergoes calcification.

Annular tearsThree types of annulus tears

Concentric(circumferential) tears

Tears between adjacent lamellae

Rim lesions

Focal circumferential avulsion of peripheral annulus

Radial fissure

Allows nucleus material to escape

STAGESBulging

At this early stage, the disc is stretched and doesn’t completely return to its normal shape when pressure is relieved. It retains a slight bulge at one side of the disc.

Some of the inner disc fibres could be torn and the soft jelly (nucleus pulposus) is spiling outwards into the disc fibres but not out of the disc

ProtrusionAt this stage, the bulge is very prominent and the soft jelly centre has spilled out to the inner edge of the outer fibres, barely held in by the remaining disc fibres.

Extrusion

In the case of a herniated spinal disc, the soft jelly has completely spilled out of the disc and now protruding out of the disc fibres.

Sequestration

Here some of the jelly material is breaking off away from the disc into the surrounding area

REFERENCES CLINICAL ANATOMY OF LUMBAR SPINE – BOGDUK

KINESIOLOGY OF THE JOINTS – KAPANDJI

CLINICAL ORTHOPAEDIC REHAB – BROTZMAN

ESSENTIAL ORTHOPAEDICS - MAHESWARI

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