Trauma / Orthopaedic Surgery

External Fixation and Internal Fixation Devices

Various Devices for Fixation

• Bone Plates and Bone Screws

- Hip lag screws

- Dynamic compression plates

- Pelvic reconstruction plates

• Tension Band Wiring
• Intramedullary Fixation
• External Fixation
• Special Devices including

- dynamic hip screws

- dynamic condylar screws

- cannulated screws

• Bone PLATES Bone and SCREWS

• HIP LAG SCREWS

These are often used in conjunction with compression plating and form the basis for AO technique. They allow compression of the fracture surface by overdrilling the proximal cortex.

• DYNAMIC COMPRESSION PLATES

These are used on the tension side of transverse or short oblique fractures. They provide stability and act as a load sharing device.

The sequence of screw placement in the contoured plate holes, is as follows:

- a neutral load drill guide, to attach plate

- an offset drill guide, to compress the fracture

- an offset guide, to further compress the fracture after screw 2 is loosened.

- at least 3 screws placed with the neutral guide

- plus an inter fragmentary screw in a different plane.

Six or more cortices are needed on each side of a forearm fracture and at least 8 cortices are needed for fixation of lower extremity and humerus fractures. Plates are usually left in place [but can be removed if there is a need] for up to 2 years.

• RECONSTRUCTION PLATES

These are used mainly for pelvic and distal humerus fractures. They are more pliable and allow positioning for use as a neutralisation plate.

• INTRAMEDULLARY FIXATION

This is a commonly used and successful method of fixation for lower extremity diaphyseal fractures:

Advantages include:

- earlier ability to weight bearing

- it can be placed in a closed position

- proper axial alignment

Disadvantages include:

- the canal diameter can limit the size of the nail

- there is less rotational control [but this can be improved with interlocking nails].

- it is sometimes technically difficult

- there is disruption of the endosteal blood supply

Orthopaedists should wait at least one year before removal.

• EXTERNAL FIXATION

This is used mainly in the management of Grade III open fractures which have a high risk of infection. The Orthopaedist maintain access to the wound while stabilising the fracture. It is used specifically in helping stabilise anterior disruptions of the pelvis, in spacing of areas wit segmental bone loss and in comminuted distal radius fractures.

• SPECIAL DEVICES

There is an ever-increasing amount. The most commonly used include:

• A SLIDING HIP SCREW

This is a load sharing device which allows screw insertion to be placed at variable angles.

• CANNULATED SCREWS

These are used in the fixation of a variety of fractures most especially femoral neck fractures. It is advisable to have a placement of K-wires prior to the insertion of the larger screws to lessen the risk of iatrogenic neurovascular injury.

• A SLIDING CONDYLAR SCREW

These can be used proximally for unstable subtrochanteric fractures but are most effective for distal femur fractures - with less than 9cm proximal to the joint.

• TENSION BAND WIRING

This technique allows fixation on the tension side, relying on motion to allow union on the compression side. Parallel K-wires need to be placed close to the outer cortex to take advantage of this design with additional wire placed under the K-wires before being tightened.

Tension Band Wiring is used most often for the fixation of patella, ankle and olecranon fractures.

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