8

Tension Band Plate

Dr. Edward L. Nazareth, Mangalore

• Eccentrically loaded

Tension side

Compression side

• 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

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

• As uniplanar forces are applied, the opposite cortex will naturally come into contact and compress

Absolute stability: tension band principle

• Contact of the opposite cortex takes stress off the tension band device.

• The resultant unit

is quite rigid.

In the excentrically loaded femur the tension side is always lateral

A plate MUST be placed on convex (tension)

side to counteract distraction forces.

Plate on concaveside distracts fx

• Requirements

Plate

Bone

• 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

This construct is very stable but requirescontact of the cortices opposite the plate.

Often unable to reduce a fracture perfectly that the opposite cortex in such perfect contact - bytechnique or the presence of comminution

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.

Application of principle of ‘tension band plate’

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.

Orientation of plates

BONE TENSION COMMON SURFACE AREAS OF PLATING

1.Humerus Posterior Posterior/ Lateral

2. Radius Radial (Lost Radial/ Volar

on motion)

Orientation of plates

BONE TENSION COMMON SURFACE AREAS OF PLATING

3.Ulna None Volar/Dorsal

4. Femur Anterolateral Posterolateral

Orientation of plates

BONE TENSION COMMON SURFACE AREAS OF PLATING

5.Tibia Anterior Lateral/Medial

6. Clavicle Anterior ? Superior (upto 90` elavation)

Orientation of plates

BONE TENSION COMMON SURFACE AREAS OF PLATING

7.Olecranon Dorsal Tension Band Wiring

8. Patella Anterior Tension Band Wiring

Traditional teaching is to apply plates perpendicular to the tension surface

• 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

It is clear, therefore, that the principles of precise tension band plating are not always required for fracture union and early motion.

Thank You