TENS Nail for Ulnar Fractures

What is TENS?

Indications

• Unstable or displaced diaphyseal ulnar fractures in children (typically ages 5-14)
• Both-bone forearm fractures (radius + ulna) - most common scenario
• Monteggia fractures - TENS nail to the ulna + closed reduction of the radial head
• Fractures that fail or are likely to fail closed reduction and casting (older children, proximal fractures)
• Re-fractures / refractures after previous manipulation
• Open forearm fractures (relative indication)

Nail Selection

• The isthmus diameter is measured on plain radiographs; reaming is rarely needed in children
• Both nails should ideally be the same diameter for balanced elastic forces
• Nails come pre-bent or are bent intraoperatively using a nail bender

Surgical Technique - Ulnar TENS Nail

Patient Positioning

• Supine with a radiolucent arm board
• Tourniquet applied at the level of the arm
• Fluoroscopy (image intensifier) mandatory throughout

Entry Point for the Ulna

1. A 1-cm longitudinal incision is made over the tip of the olecranon
2. The triceps insertion is split longitudinally
3. The starting point is created 5-8 mm from the dorsal cortex and 5 mm from the lateral cortex of the proximal ulna
4. This positioning allows insertion of a straight nail despite the natural lateral bow of the ulna, and avoids the articular surface of the greater sigmoid notch
5. A drill guide is strongly recommended to protect surrounding soft tissues
6. ⚠️ The ulnar nerve is at special risk during creation of the proximal ulna entry point

Alternatively, the ulna can also be nailed retrograde (distal to proximal), entering just proximal to the distal ulnar physis. The antegrade approach is preferred for most shaft fractures.

Nail Insertion Steps

1. Prepare the canal: If open reduction is performed, ream the canal through the fracture site both proximally and distally. Reaming of the distal segment is important as cancellous bone can impede nail advancement and cause fracture distraction
2. Bend the nail: Adjust nail geometry to match the lateral bow of the ulna using a nail bender
3. Advance the nail: Insert the nail with a T-handle driver or inserter. Keep a short working length (3-5 cm between entry point and inserter) for better control
4. Reduce the fracture: The nail tip can be used as a lever to assist in closed reduction as it approaches the fracture site
5. Cross the fracture site under fluoroscopic guidance and seat the nail distally
6. Cut the nail tail: Cut the nail close to the bone (or slightly proud). If using a lateral entry, ensure the nail end does not irritate the superficial radial nerve
7. End caps: Optional - can be inserted over nail ends to reduce irritation and migration

⚠️ Do not use a hammer if the nail is stuck (especially in young children with narrow canals) - withdraw 2 cm, rotate to free the tip, then re-advance.

Order of Fixation (Both-Bone Forearm)

• Fix the radius first (retrograde, distal entry near Lister tubercle) - this is usually advantageous
• If the radius is difficult to reduce, use a distal ulnar entry for both nails so they go in the same direction, enabling simultaneous manipulation
• If the radius reduces easily, choose the ulnar entry point furthest from the fracture to give maximum working length
• Fix the less comminuted fracture first to guide reduction of the other bone

Aftercare

• Cast immobilization is not strictly necessary but is often applied for 3-4 weeks for comfort, especially in younger children
• For Monteggia type, immobilize in the position of maximum stability of the radiocapitellar joint for 2-4 weeks
• Encourage use of the arm early
• First follow-up (clinical + radiological): 4-6 weeks post-op
• Mean union time: approximately 10 weeks

Nail Removal

• Delayed until fracture has remodeled completely
• Performed as a day case under general anaesthesia
• The proximal ulna nail end can often be easily palpated
• Distal nail tips may slip under tendons/nerves and can be difficult to locate

Outcomes

Complications

TENS vs. Plate Fixation (Adults)

• Plates restore cortical contact and rotational stability better
• IM nails (including elastic nails) cannot control rotation and axial length in comminuted patterns without locking
• Union rates with plates approach 97-100%

• Rockwood and Green's Fractures in Adults, 10th ed. 2025 - Intramedullary Nailing of Forearm Fractures
• AO Surgery Reference - ESIN for Forearm (Pediatric Trauma)
• Jain S et al. Acta Orthop Belg. 2023 - PMID 37935240
• Bhat et al. Trauma Monthly. 2022
• PMC5198410 - Prospective study of 50 cases