Tension Band Principles (TBW)

Tension band principles are used to fix the fractures where there are tensile sites and compressible sites by the use of these principles.

Column: When loaded in its central axis displays compression stress in horizontal cross-section evenly

But in eccentric column loading, the Stress pattern changes

There are 2 elements(due to bending):

1. Compression elements
2. Tension elements

i.e. more eccentric loading more bending components

The tensile forces provided by eccentric loading can be converted into compressive loading.

This is used in fracture fixation by application of tension band.

If tension band is applied prior to eccentric loading that would otherwise stretch the opposite spring thus cause uniform compression of both springs.

Eg. Wires, cables, non absorbable sutures, plates can be used as tension band principles

This help to obtain excellent fractures stability and immediate functional movement of the contiguous joints.

The use of wires for fixation of tension surface of the fracture bone converts the distracting tensile force into converting force, such wire is called tension band wiring

1. Wires must be applied in the tension surface of bone
2. Wires must be pre stressed (tightened): Compression on fracture site and slight gap on opposite side
3. Wires must be strong to withstand tension load
4. Strong opposite bone cortex should be present to withstand dynamic compression load

“Wire absorb the tensile force and bone withstand the compression load”

 “So, when dynamic forces are applied with contraction of antagonist deforming muscles during normal activity–>tension band resists the activity that tends towards distraction of opposite side of fracture bones–>but produces uniform compression at fracture sites.”

The anterior cortex closed and the posterior cortex opens up, but when knee flexes it closes the posterior gap by quadriceps force and patella tendon force distracting while TBW provided compression in it.

Used of TBW

1. Transverse / Communited fractures
2. Fractures/ Osteotomy of GT
3. Medial / Lateral malleolus fractures
4. Fractures of GT
5. Fracture of distal end of clavicles
6. Fracture olecranon process of ulna

See also: Extensor Fixator Principles