Basics of pin placement
To ensure effective traction, the metal pin must be inserted strictly perpendicular to the axis of the injured bone. Violating this angle will inevitably lead to device migration, soft tissue cut-through, and loss of treatment efficacy.
Key anatomical landmarks for pin insertion:
- Tibia: the pin is inserted from lateral to medial, 1 cm distal and 1.5 cm dorsal to the apex of the tibial tuberosity. Special consideration: in children, the pin is inserted exclusively through the metaphysis to avoid cutting through immature tissue and to prevent damaging the growth plate.
- Supramalleolar area: the entry point is located 1.5–2 cm proximal to the most prominent part of the medial malleolus.
- Calcaneus: the intersection of the diagonals of a square (constructed from the lateral malleolus) method is used, or the perpendicular segment is bisected with the foot set at a right angle.
- Olecranon: the patient's arm is flexed 90 degrees at the joint, and the entry point is located 2–3 cm distal to the tip of the olecranon.
To prevent infectious complications, the metal exit sites on the skin must be protected with alcohol gauze balls tightly secured with rubber stoppers.
Traction biomechanics and load calculation
Traction force directly depends on the patient's body weight and the fracture localization. It should be kept in mind that the actual force acting on the bone fragments is always lower than the suspended load weight due to natural friction in the pulley system.
Approximate calculations:
- Femur: approximately 1/7 of the patient's weight (on average from 6 to 12 kg).
- Leg: about 1/14 of body weight (from 4 to 7 kg).
- Humeral diaphysis: from 3 to 5 kg.
Important rule: it is strictly forbidden to suspend the entire calculated weight all at once, as abrupt stretching will provoke persistent muscle spasm. Start with 1/3 to 1/2 of the calculated mass. Then the weight is smoothly increased, adding 1 kg every 1–2 hours until the required traction force is achieved. To dampen sudden accidental jolts in the system, a damping spring must be installed between the traction bow and the load.
Stages of reduction and fragment retention
The process of aligning bone fragments on traction does not happen instantly—it lasts up to 7–10 days and requires regular clinical (limb length assessment, palpation) and radiological monitoring.
- Elimination of displacement along the length. This is the starting stage. Axial traction gradually fatigues the muscles resisting the stretch. Interestingly, restoring the normal length of the segment often spontaneously corrects the displacement of fragments across the width as well.
- Elimination of complex displacements. If displacement across the width or rotation persists, the physician resorts to additional measures: changing the spatial position of the bow, using plaster or bandage side pads, or applying special pins with a stopper plate for direct lateral traction.
- Fixation. As soon as the fragments are in the correct position, the load is gradually reduced to half of the initial one. This is a critically important action to prevent tissue overdistraction and the formation of interosseous diastasis (gapping).
Unlike a solid plaster cast, skeletal traction does not provide absolute rigid fixation. The resulting minor rocking movements in the fracture zone form microhematomas, which serve as a powerful natural stimulus for callus formation.
Indications for the method
Skeletal traction is used in traumatology in two main formats:
- As an independent treatment: for intra- and extra-articular fractures of the femur, tibia, humerus, scapula, calcaneus, and metatarsal bones. The method is also effective for joint unloading in fractures of the acetabular floor or in severe pelvic ring injuries with displacement.
- As an auxiliary stage: for smooth tissue stretching prior to surgical osteosynthesis, arthroplasty, or reduction of chronic dislocations. The method is indispensable for fracture immobilization in cases where casting is contraindicated (with extensive wounds, phlyctenas, severe edema, burns, or skin degloving).
General therapy during traction
Severe trauma inevitably triggers systemic catabolic processes, so mechanical reduction is always supplemented with comprehensive conservative therapy.
- Nutrition and metabolism: a high-calorie diet emphasizing protein is prescribed. Given the risk of stress hyperglycemia (especially in patients with diabetes mellitus), strict blood sugar control is required.
- Pharmacological support: strong analgesics and amino acid solutions are used. An important nuance is that calcium supplements are advisable only starting from the second stage of bone regeneration (on days 10–14).
- Physical therapy: hyperbaric oxygenation (HBO) is successfully used to eliminate systemic and tissue hypoxia. Magnetotherapy, UHF therapy, laser therapy, and electrical stimulation of the fracture zone are used to suppress inflammation and stimulate callus formation.
For a safe start of traction, remember: never hang the entire weight at once! Start with a third or half, adding a kilogram every 1–2 hours to "fatigue" the muscle reflex rather than provoke a spasm.
Class and exam questions
Why is it necessary to step away from the cortical layer of the bone when inserting a pin?
Inserting the pin too close to the edge of the cortical layer creates a high risk of it cutting through the bone tissue under the constant pull of the load.
What happens if the pin is insufficiently tensioned in the bow?
With insufficient tension, the pin will begin to bend under load. This will lead to soft tissue cut-through, skin damage, and a high risk of subsequent suppuration.
Why is the tibial pin inserted differently in children?
In pediatric patients, the pin is inserted through the metaphysis (rather than the tuberosity itself) to guarantee no damage to the growth plate and to prevent cutting through soft children's bone.
How is rotational displacement corrected during traction?
To eliminate displacements across the width and rotation, traumatologists manipulate the position of the bow with the fixed pin, use bandage pads, or insert additional pins with stopper plates.
What else to study on this topic
- Alternative techniques: insertion of Schanz screws into the femoral neck and Klapp traction of the phalanges.
- Patient positioning features: use of the Böhler splint and the TsNIITO abduction splint.
- Multiple skeletal traction: indications in polytrauma and pelvic fractures.
- Historical aspect: traction on multiple pins for pressure ulcer prevention in tetraplegia.
- Physiotherapeutic methods in traumatology: HBO, UHF, and balneotherapy.
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