Biomechanic Of Spine

Heri Sutanto

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Biomechanics of the Spine & Hip• Movements of Spine• Flexion, Rotation, Extension, Abd, Add.

• Hip Movements• Elevation, Anterior & Posterior Tilt, Flexion, Extension,

Abd, Add, Hyperext, Hyperflex

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Spinal Deviations

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Forces Acting On The Spine

• Forces Acting On The Spine Include:– Body Weight– Tension In The Spinal Ligaments– Tension In The Surrounding Muscles– Intraabdominal Pressure

• The Major Form Of Loading On The Spine Is:– Axial

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Upright Position

• Spinal Compression– Resulting From:

– Body Weight + Weight Held by Arms and Hands

• When Standing Upright– Total Body Center of Gravity

Is Anterior to the Spinal Column.

– Spine Is Placed Under Constant Forward Bending Moment.

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Loads on the Spine

Because the spine is curved, body weight, acting vertically, has components of both compression (Fc) and shear (Fs) at most motion segments.

Fc

Fs

wt

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Loads on the Spine

During lifting, both compression and anterior shear act on the spine. Tension in the spinal ligaments and muscles contributes to compression.

Muscle tension

Shear reaction force

Compression reaction force

Joint center

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Sample Problem 1

How much tension must be developed by the erector spinae with a moment arm of 6cm from L5-S1 joint center to maintain the body in the position shows on your right?

Given that

Head : 58 N Arms : 81 N

Trunk : 328 N Box : 111 N

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Loads on the Spine

Lumbar hyperextension can create a bending load (moment) in the posterior direction.

compression tension

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Loads on the Spine

hyperextension

Lumbar hyperextension produces compressive loads at the facet joints.

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Loads on the Spine

Spinal rotation generates shear stress in the intervertebral discs.

Superior view Lateral view

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Human Posture When Lifting

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Common Injuries

Low back painSoft tissue InjuriesAcute fracturesStress Fracture – spondylolysis (fracture

in vertebral neural arch)Disc herniation

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• Fungsi facet joint?

• Knp hyperex bs terjadi?