Bones of the lower extremity

Foot and ankle fractures

Management tactics for distal lower extremity injuries depend on the specific bone and the patient's age.

• Calcaneus: Injury most commonly occurs from a fall from a height onto extended legs. The main radiological criterion is the talo-calcaneal angle. If it exceeds 140–160°, the arch of the foot flattens, which is a direct indication for reduction. In case of displacement, a long cast is applied up to the middle third of the thigh (knee and hip joints flexed at 90°), and after 12–16 days, the foot is moved into a mid-physiological position and a boot-shaped cast with an arch support is formed.
• Talus: Fractures in children are extremely rare and usually without displacement. An important diagnostic nuance: up to age 16, the posterior process of the talus is visualized on radiographs as a separate bone.
• Metatarsals: Lead in the frequency of injuries in children. Injury mechanisms are divided into direct (fall of a heavy object), indirect (striking the toe), and specific (foot getting caught in the spokes of a rotating bicycle wheel).
• Tibia and malleoli: After edema subsides, a circular cast is applied for 2–3 weeks. Injury to the distal metaepiphysis in children is dangerous due to premature closure of the growth plate. This causes stunted growth of the medial edge of the bone and the formation of a varus deformity, which is why such patients are monitored by an orthopedist for at least 2–3 years.

Immobilization principles and early functional loading

The rate of consolidation directly depends on the fracture plane and its location. Transverse fractures allow loading earlier than spiral ones, and the lower third of the tibia heals slower than the upper and middle thirds. The average immobilization period is 12–14 weeks, but with extensive soft tissue damage and comminuted fractures, it is extended to 16 weeks or more.

For the treatment of diaphyseal fractures of the middle and lower thirds of the leg, the early functional loading method is used — shortened plaster casts:

1. Cast "with foot": anteriorly it reaches the lower pole of the patella, posteriorly it descends so that the popliteal fossa remains free. A heel or stirrup for support is molded into the distal part.
2. Cast "without foot" (boot type): reaches the upper pole of the patella, the popliteal fossa is free, a stirrup is installed at the bottom.

These casts preserve movement in the knee joint and allow for graded weight-bearing. Transitioning to them is possible after 1.5–2 weeks in transverse fractures without displacement. Before getting the patient up on crutches, "venous gymnastics" must be performed — periodically lowering the leg into a vertical position followed by returning it to the bed.

Skeletal traction: calculations and biomechanics

The basis of reduction via skeletal traction is the elimination of length displacement through axial traction. A gradual increase in weight fatigues the muscles resisting the stretch, often automatically eliminating displacement in width as well.

• Mass calculation: For the femur, approximately 1/7 of body weight is taken (on average 6–12 kg), for the lower leg — 1/14 (4–7 kg). It is important to remember that the actual force acting on the bone is always less than the weight of the load due to friction losses in pulleys and suspensions.
• Suspension rules: It is strictly forbidden to hang the entire calculated load at once, as sudden stretching causes persistent reflex muscle contraction. Start with 1/3–1/2 of the calculated mass, adding 1 kg every 1–2 hours.
• Positioning: The patient is placed on a bed with a firm board. To balance the pull of antagonist muscles, a Beller splint is used. Traction must be strictly along the axis of the segment, otherwise part of the force is lost according to the parallelogram rule. To absorb accidental jolts, a damping spring is installed, and to prevent slipping, the foot of the bed is elevated.
• Alternative techniques: In acetabular fractures and central hip dislocation, traction is performed via the greater trochanter (using a cancellous screw or Schantz pin). For toe phalanges, Klapp traction is used — a wire is passed through the phalanx and traction is applied using rubber pullers to a metal arch on the plaster.

Class and exam questions

What else to study on this topic

• Biomechanics of traction force losses in skeletal traction (parallelogram rule).
• Technique of Schantz pin insertion in central hip dislocation.
• Features of consolidation of spiral and comminuted fractures with displacement.
• Methodology of performing "venous gymnastics" before patient verticalization.
• Dispensary monitoring of children with tibial metaepiphysis injuries.

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.