If there is only a small degree of force through the fracture it might be fixed by using fixation wires or pins, and they are also employed to add to the effect of inserting an external fixator or a plate. The most common fractures for which fixation with pins or wires are used are those of the wrist, upper humerus, hand and fingers. Fractures of the ankle, elbow and kneecap are also assisted by k-wiring to add to the tension band technique often used here. Pins can be inserted through the skin without performing an open operation by using an x-ray guidance system.
Larger than wires and able to be threaded, Steinmann pins are typically employed to apply traction skeletally for one of the long bones, mostly in the leg. They are driven through the bone and attached to a weight via a stirrup-like device which applies the traction to maintain bony alignment until sufficient callus has formed for the traction to be removed. Traction is used much less often now as this technique has been overtaken by more advanced methods of internal fixation which allows us to avoid the negative consequences of long term bed rest needed for traction.
Fixation Screws
A basic tool in the armoury of managing orthopaedic and trauma injuries and conditions is the use of bone screws to effect fixation or to aid other techniques of fixation. Pre-drilling can be performed before insertion or a self tapping implant used. The amount of physical stress which can pull a screw out of the bone is affected by a series of matters of which the most influential is the density of the bone into which it is implanted. The surface area of contact between the bone and the screw threads determines a degree of the fixation achieved. Screw insertion is performed in a clockwise direction either along a drilled path or self tapped and produces force once the hard bone cortex is contacted by the head of the screw.
Bone adapts to the tension and the force applied by the screws decreases gradually with time, however the time for this to occur to loosen the compression is typically longer than the time needed for fracture healing. Cortical and cancellous screws are the two types available, with cortical screws used for the denser bone of the long bones and cancellous screws for the less dense bone of bone ends. Cortical screws have less and cancellous screws more surface area for purchase on the bone. Cancellous screws are used in the softer bone and cortical screws in harder bone.
Cancellous bone does not usually need tapping or pre-drilling, as it is less dense, more porous and can easily be screwed into. It may be advantageous to directly screw into this type of bone as this may make the bone more compressed over the insertion track and allow the screw to hold more strongly. An implant mechanism such as a plate can be held in place by positional screws and compress the metal plate against the bone. A pilot hole is typically drilled to start with and then the hole tapped with a screw thread unless self tapping screws are to be used.
A degree of compression can be produced by inserting lag screws across the line of a fracture to increase alignment and stability of a long bone fracture and to produce and maintain reduction of a fracture across a joint. To provide the greatest degree of stability requires the screw to be placed at right angles to the line of the break. It is unlikely that lag screws will give sufficient stability alone so they are often supplemented with added stability from an external fixator or a plate.
Cannulated screws are often used to fix hip fractures and can be inserted percutaneously without needing a full open operative technique, inserting the screw along the track already identified by a guide wire and performed under x-ray control for positional control. To limit the potential damage to the soft tissues and the size of the operation, cannulated screws are employed in operations with limited open surgery. Modern screws are self tapping and self drilling as they are inserted and are much more costly than normal screws which are not cannulated. - 14130
Larger than wires and able to be threaded, Steinmann pins are typically employed to apply traction skeletally for one of the long bones, mostly in the leg. They are driven through the bone and attached to a weight via a stirrup-like device which applies the traction to maintain bony alignment until sufficient callus has formed for the traction to be removed. Traction is used much less often now as this technique has been overtaken by more advanced methods of internal fixation which allows us to avoid the negative consequences of long term bed rest needed for traction.
Fixation Screws
A basic tool in the armoury of managing orthopaedic and trauma injuries and conditions is the use of bone screws to effect fixation or to aid other techniques of fixation. Pre-drilling can be performed before insertion or a self tapping implant used. The amount of physical stress which can pull a screw out of the bone is affected by a series of matters of which the most influential is the density of the bone into which it is implanted. The surface area of contact between the bone and the screw threads determines a degree of the fixation achieved. Screw insertion is performed in a clockwise direction either along a drilled path or self tapped and produces force once the hard bone cortex is contacted by the head of the screw.
Bone adapts to the tension and the force applied by the screws decreases gradually with time, however the time for this to occur to loosen the compression is typically longer than the time needed for fracture healing. Cortical and cancellous screws are the two types available, with cortical screws used for the denser bone of the long bones and cancellous screws for the less dense bone of bone ends. Cortical screws have less and cancellous screws more surface area for purchase on the bone. Cancellous screws are used in the softer bone and cortical screws in harder bone.
Cancellous bone does not usually need tapping or pre-drilling, as it is less dense, more porous and can easily be screwed into. It may be advantageous to directly screw into this type of bone as this may make the bone more compressed over the insertion track and allow the screw to hold more strongly. An implant mechanism such as a plate can be held in place by positional screws and compress the metal plate against the bone. A pilot hole is typically drilled to start with and then the hole tapped with a screw thread unless self tapping screws are to be used.
A degree of compression can be produced by inserting lag screws across the line of a fracture to increase alignment and stability of a long bone fracture and to produce and maintain reduction of a fracture across a joint. To provide the greatest degree of stability requires the screw to be placed at right angles to the line of the break. It is unlikely that lag screws will give sufficient stability alone so they are often supplemented with added stability from an external fixator or a plate.
Cannulated screws are often used to fix hip fractures and can be inserted percutaneously without needing a full open operative technique, inserting the screw along the track already identified by a guide wire and performed under x-ray control for positional control. To limit the potential damage to the soft tissues and the size of the operation, cannulated screws are employed in operations with limited open surgery. Modern screws are self tapping and self drilling as they are inserted and are much more costly than normal screws which are not cannulated. - 14130
About the Author:
Jonathan Blood Smyth is the Superintendent of Physiotherapists at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for physiotherapists in Leicestervisit his website.
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