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Tension Band Plate
Dr. Edward L. Nazareth, Mangalore
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• Eccentrically loaded
Tension side
Compression side
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• Eccentically loaded fractured bone, to minimize the forces on the fixation device
1. Absorb the tensile forces (bending moment )
2. Convert them into compression forces
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Tension Band Plate
A plate applied to the tension side of a bone so that tension forces on the plate side of the bone are converted to compression forces on the opposite cortex
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• As uniplanar forces are applied, the opposite cortex will naturally come into contact and compress
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Absolute stability: tension band principle
• Contact of the opposite cortex takes stress off the tension band device.
• The resultant unit
is quite rigid.
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In the excentrically loaded femur the tension side is always lateral
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A plate MUST be placed on convex (tension)
side to counteract distraction forces.
Plate on concaveside distracts fx
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• Requirements
Plate
Bone
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• The plate must be of material that resists tensile forces it can be prestressed
-- in tension leads to axial compression
-- eccentrically loaded converts tensile forces into compression
• The bonemust withstand compressionshould not be comminuted on either side
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This construct is very stable but requirescontact of the cortices opposite the plate.
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Often unable to reduce a fracture perfectly that the opposite cortex in such perfect contact - bytechnique or the presence of comminution
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A gap on the compression cortex….stability of construct depends on:-The thickness of the plate -The ability of screws to resist pull out
This allows for potential failure.
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Application of principle of ‘tension band plate’
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Tension-compression sides?
• Except patella and olecranon, most bones are not subjected to uniplanar stresses.
• Tension surfaces are often identified but are not pure-- some stresses out of the tension are passed onto the compression axis.
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Orientation of plates
BONE TENSION COMMON SURFACE AREAS OF PLATING
1.Humerus Posterior Posterior/ Lateral
2. Radius Radial (Lost Radial/ Volar
on motion)
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Orientation of plates
BONE TENSION COMMON SURFACE AREAS OF PLATING
3.Ulna None Volar/Dorsal
4. Femur Anterolateral Posterolateral
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Orientation of plates
BONE TENSION COMMON SURFACE AREAS OF PLATING
5.Tibia Anterior Lateral/Medial
6. Clavicle Anterior ? Superior (upto 90` elavation)
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Orientation of plates
BONE TENSION COMMON SURFACE AREAS OF PLATING
7.Olecranon Dorsal Tension Band Wiring
8. Patella Anterior Tension Band Wiring
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Traditional teaching is to apply plates perpendicular to the tension surface
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• The amount of metal in the plane of greatest stress determines the strength of the construct.
• Bending is through the width, not the thickness of the plate.
• With a slightly imperfect reduction and a not precisely controlled axis of motion, adequate strength is achieved while still allowing some flexibility
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It is clear, therefore, that the principles of precise tension band plating are not always required for fracture union and early motion.
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Thank You