Muhammed Nazeer MS,FRCS

• To learn how absolute stability can be obtained using plates

• To differentiate between plate name and function

• To learn how different types of plate function can produce absolute stability

• To show how to reduce the biological price of rigid fixation using plates

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• Refers to shape or design

• Catalogue name

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• “Surfaces of the fracture do not displace under functional load”

• Can only be achieved by interfragmentary compression

Absolute stability

• A plate by itself rarely provides absolute stability

• The key tool of absolute stability is the lag screw

Compression must sufficiently neutralize all forces[bending, tension, shear and rotation]

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The surgeon not the designer of the plate determines how a plate will function and how it will be applied

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• Neutralization[Protection] plate

• Compression plate

• Tension band plate

• Buttress plate

• Bridge plate—relative stability

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• Reduces torsional and axial forces on interfragmentary compression screw(s)

• Always used with lag screws

• Requires anatomical reduction

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• Requires a transverse or short oblique fracture pattern

• Requires a simple fracture pattern

• Requires perfect plate contouring

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Compression plate:eccentric DC (dynamic compression) hole

Removable device:compression device

Interfragmentary compression by plate

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Axial compression with removable compression device

Metaphysis: plate contoured butslightly less (shorter) than bone,bone is pulled towards plate

Diaphysis: in order to compressOpposite cortex plate must be prebent

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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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• Only works if you have a true tension side

• Only works if opposite cortex is intact

• Converts tension forces to compression forces on opposite cortex

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Absolute stability: tension band principle

In the eccentrically loaded femur the tension side is always lateral.

A plate MUST be placed on convex (tension) side to counteract distraction forces.

However there must also be a medial bony buttress, if missing, the plate will break due to fatigue.

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Plate on concave side distracts fracture

Absolute stability: tension band principle

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•Resist axial load by applying force at 90 degree to the axis of potential deformity

•Metaphyseal tibial plateau split fractures

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• Used when the fracture will only displace in one direction

• Only useful in metaphyseal fractures

• Applied so as to resist one deforming force

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Plate may be a reduction tool

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Direct (primary) bone healing without visible, external callus

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Absolute stabilityonly after rigid fixation withinterfragmentary compression

Internal remodelling replaces dead structures

Fracture gradually disappears

Minimal periosteal callus

Direct (primary) fracture healing

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Hazards of absolute stability

Too aggressive exposure, periosteal strippingLack of respect for vascularity of all tissuesPoor soft-tissue careToo much metalToo stiff constructSlow healing

Catastrophies

Careful technique interfragmentary compression absolute stability

Errors in technique and principles complications• Delayed healing• Implant failures • Nonunions• Wound complications and infections

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• Cortical blood supply damage—potential problem

• Devascularization and transient osteoporosis beneath plate

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• Change the design of the plate

• Change the surgical technique

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• Plates rely on friction between the plate and bone to achieve stability

• The bone under the plate will always suffer a degree of vascular damage

• The smaller the footprint of the plate the less the damage will be

• Gradual evolution of plate design• Minimize detrimental effects on bone

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DCP

LC-DCP

PC-Fix

LCP

Preservation of the soft-tissue envelope profoundly affects bone healing

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• Always preserve soft tissues

• Use the least amount of metal

• Percutaneous approaches

• MIPO (minimally invasive plate osteosynthesis)

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Biological fixation & absolute stability?

• Balance between surgical fracture stabilization and the insult to the biology caused by the technique

• A demanding surgical technique requiring much experience and the correct indications

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Absolute stability of conventional plating

Biologic damage of surgical dissection and open reduction

Respect for soft-tissue envelope surrounding fractures is essential

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Caution! Open carefully, intraarticular fracture inside

No returns or second chances

Handlewithcare

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Fractures requiring anatomical reduction and early functional aftercare

• articular fractures

• forearm fractures: closed/open

Fractures not suited for relative stability

• simple (type A) metaphyseal fracture

•Function of the plate is not the design but the surgeons technique

Utmost care for the vascularity of soft tissues, periosteum, and bone!

Take home message