Courtesy: Sandeep Patwardhan, Ashok Shyam, IORG and OrthoTV

 

TENS Nailing for Femoral Fractures in Children

Indications

• Age 5–12 years.
• Weight <45–50 kg.
• Transverse fractures.
• Short oblique fractures.
• Minimally comminuted fractures.
• Midshaft fractures are the ideal indication.

Relative Contraindications

• Highly comminuted fractures.
• Very proximal or distal fractures.
• Heavier children >50 kg.
• Long oblique or length-unstable fracture patterns.

Principle

• TENS provides elastic stable intramedullary fixation.
• Two pre-bent nails create a balanced spindle construct.
• The construct provides three-point fixation.
• Stability combined with controlled micromotion promotes callus formation.
• TENS works best in length-stable fractures.

Nail Selection

• Each nail diameter = 0.4 × the narrowest canal diameter.
• Two nails together should fill approximately 80% of the canal.
• Use equal-sized nails on both sides.

Preoperative Setup

• General anesthesia.
• Supine position on a radiolucent table.
• C-arm aligned with the surgeon.
• Required instruments include nails, awl, T-handle, bending tools, hammer, and inserter/extractor.

Surgical Technique

Reduction

• Achieve alignment using traction.

Nail Bending

• Bend both nails symmetrically.
• The apex of the bend should correspond to the fracture level.
• The nail should have a hockey-stick configuration.
• Height of the bend = approximately 3 × canal diameter.

Entry Point

• Use medial and lateral entry points.
• Entry points are approximately 2 cm proximal to the distal femoral physis.
• Position the entry slightly posteriorly to reduce the risk of joint irritation.
• Avoid injury to the physis.

Nail Insertion

• Insert the first nail and advance it toward the fracture.
• Insert the second nail in the same manner.
• Use gentle oscillating movements rather than forceful advancement.

Crossing the Fracture

• Reduce the fracture.
• Pass the easier nail first.
• Then pass the second nail.
• Rotation can assist passage.
• Slight withdrawal and redirection may be required.

Final Position

• The nails should diverge proximally.
• The lateral nail should reach toward the greater trochanter.
• The medial nail should reach toward the femoral neck region.
• Avoid physeal injury.

Seating and Cutting

• Cut the nails, leaving approximately 1 cm outside the cortex.
• Avoid leaving long, bent nail ends because they can cause irritation.
• Seat the nails flush with the cortex using a tamp.

Final Check

• Confirm alignment on AP and lateral views.
• Check rotational alignment carefully.
• Confirm stability.

Biomechanics

• The opposing elastic forces provide axial stability.
• They also provide rotational control.
• The construct is most effective in length-stable fractures.

Postoperative Protocol

• Plaster immobilization is usually not required.
• Knee mobilization can begin around day 2–3.
• Partial weight bearing can begin around day 3–4.
• Progress weight bearing over approximately 3–4 weeks.
• Good callus formation is expected by around 6 weeks.
• Union is expected at approximately 3 months.

Implant Removal

• Removal is generally around 6–9 months.
• Ideally, removal should occur before 18 months.
• If extraction is difficult, the nail can be bent approximately 90° using a hollow tube and then extracted.

Complications

• Malalignment, including varus, valgus, and rotational deformity.
• Nail irritation at the entry site.
• Knee stiffness.
• Infection.
• Refracture after nail removal.
• Limb length discrepancy.

Exam Pearls

• Best age: 5–12 years.
• Best fracture: Transverse midshaft fracture.
• Nail diameter: 40% of the canal diameter for each nail.
• Combined canal fill: Approximately 80%.
• Two nails: Equal size and symmetrically bent.
• Key principle: TENS works best for length-stable fractures.
• Always avoid physeal injury.