Traction produces a reduction through the surrounding soft parts which align the fragments by their tension.
When the shaft of a long bone is fractured the elastic retraction of muscles surrounding the bone tends to produce over-riding of the fragments. This tendency is greater when the muscles are powerful and long bellied as in the thigh, when the fracture is imperfectly immobilised so that there is pain and therefore muscle spam and when the fracture is mechanically unstable because the fragments are not in apposition or because the fracture line is oblique.
Continuous traction generated by weights and pulleys in addition to causing reduction of a deformity will also produce a relative fixation of the fragments by the rigidity conferred by the surrounding soft tissue structures when under tension. It also enables maintenance of alignment while at the same time it is possible to devise apparatus which permit joint movement.
Traction may be applied through traction tapes attached to skin by adhesives or by direct pull by transfixing pins through or onto the skeleton.
Traction must always be apposed by counter traction or the pull exerted against a fixed object, otherwise it mealy pulls the patient down or off the bed.
Traction requires constant care and vigilance and is costly in terms of the length of hospital stay and all the hazards of prolonged bed rest - thromboembolism, decubiti, pneumonia and atelectasis must be considered when traction is used
Excessive traction which leads to distraction of the fracture is undesirable. Once the fracture is reduced a decreasing amount of weight is required to maintain a reduction once the muscle stretch reflex has been overcome and the fracture immobilised. For a femoral fracture no more than 10lbs should be used and for fractures of the tibia and upper limb less weight is required.
Traction is applied to the skeleton through its attached soft tissued and in the adult should be used only as a temporary measure.
Skin is designed to bear compression forces and not shear. If much more than 8lbs is applied for any length of time it results in superficial layers of skin pulled off. Other difficulties such as migration of the bandage may occur with lower weights.
First achieved by the use of tongs.
The application of traction applied by a pin transfixing bone was introduced by Fritz Steinmann. Now a threaded Denham pin is preferred to prevent early loosening of the device.
The threaded portion of the Denham pin is offset, closer to the end of the pin held in the drill chuck and should engage only the proximal cortex of the recipient long bone.
Traction by Gravity
Really only applies to fractures of the upper limb (hanging cast)
Traction on a limb demands either a fixed point from which the traction may be exerted (fixed traction) or an equal counter-traction in the opposite direction (balanced traction)
The length of the limb remains constant and there is continuous diminution of traction force as the tone in the muscles diminishes and no further stimuli results in activation of the muscle stretch reflex.
Pull is exerted against a fixed point for example tapes are tied to the cross piece of a Thomas splint and the leg pulled down until the root of the limb abuts against the ring of the splint.
Pins in plaster is a form of fixed traction
In weight traction it is the tension in the apparatus which remains constant and the length depends on the amount of tearing of the intermuscular septum and fibrous tissue of the limb
The pull is exerted against an opposing force provided by the weight of the body when the foot of the bed is raised.
May be used in conjunction with fixed traction where the weight takes up any slack in the tapes or cords while the splint maintains a reduction.
This combination facilitates less frequent checks and adjustment of the apparatus
First introduced by Pugh by applying traction tapes to the limb and fastening them to the raised foot of the bed which was then inclined head down.
He utilised this traction in the treatment of conditions such as Perthes where only one limb was fastened to the end of the bed enabling the pelvis on the opposite side to slide down the bed more thus creating traction and abduction.
The extent to which the patient slides down the bed is limited by the friction of the body against the mattress.
The traction was subsequently modified by Hendry using a mattress on a sliding frame which resulted in the same amount of traction with an inclination of 10o as that with that on a normal mattress at 30 - 40o inclination.
This is also really a form of balance traction where the amount of weight is determined by the inclination of the bed.
Specific Types of Traction
Thomas Splint Traction
Hugh Owen Thomas introduced his splint which he called "The Knee Appliance" in 1875.
The method of Hugh Owen Thomas uses fixed traction with the counter traction being applied against the perineum by the ring of the splint. This is in contrast to other methods using weight traction which is countered by the weight of the body.
Backward angulation of the distal fragment can never be corrected by traction in the axis of the femur which only results in elongation with persistence of the deformity.