TENS nailing

Basic principles

In principle uses 3 point fixation.

Pre bend 3* diameter of isthmus (where using two nails). Debatable some surgeons don't pre bend allow nails to follow contour of bone.

Ensure the apex of the bend is at the level of fracture site.

Balance is important, use entry points at same level, use nails of similar diameter and bend. (Unless really advanced TENS nailing and using smaller nail to balance forces of muscle pull).

Use nail 40% of diameter if using 2 nails eg. Femur or Tibia; 60% if only using one nail eg. Radius and Ulna.

Forearm

Retrograde nailing of radius and ante or retrograde nailing of ulna

Single nail hence 60% diameter canal.

Pre bending not normally necessary, ulna is straight, if bending radius consider bow of radius.

Do most difficult nail first often radial nail.

Radial nail

Entry point lateral or dorsal avoiding physis, use bone awl not drill.

Lateral beware superficial radial nerve (Personal choice is lateral)

Dorsal, through Listers tubercle, ensure when cutting wire that it is placed well outside the tendon compartment to prevent any tendon injury by continuous friction over the nail ends.

Be prepared to do small open reduction at fracture site, can be difficult to reduce and pass wire.

Distal shaft fractures require a radial nail insertion site as far distally as possible, but at least 5 mm from the epiphyseal plate, in order to reach the opposite inner cortex before crossing the fracture, which is essential for a stable fixation. Otherwise the distal fragment is fixed at the entrance point of the nail only and tends to tilt. A descending radial nailing is not advisable because of the risk of
injuring the deep radial nerve.

Ulnar nail

Entry point distal medial metaphysis or proximal lateral plane (antegrade more common)

As for radius advance to fracture pass closed if possible if not do mini open reduction.

Turn tips of both nails towards each other to spread the interosseous membrane.

Cut and bury ends of the nails.

Generally children with ESIN do not need a cast, encourage immediate movement.

Remove nails depending on healing around 3 months, some groups wait 8 months.

Radial neck

Use 1.2-2.5 mm TENS nail, use same entry as for distal radius, advance retrograde to radial neck.
Direct the point to face the inferior aspect of the fracture, where the tilt is the greatest.

Advance nail with gentle taps on hammered, elevating and transfixing the radial head, repositioning it under the lateral condyle.

Once the tilt has been corrected, correct the lateral shift by rotation the TENS nail around 180º so the point faces inward.

If needed aid reduction with digital pressure or percutaneous wire to push radial head into place.

Immobilize in cast 2 weeks, followed by ROM, wire out after 8 weeks.

Tibia

Usual treatment is non operative. TENS nailing if failure of non operative Rx, segmental fracture, polytrauma, grade I and II open (consider ex fix for grade III).

Use 2 pre bent nails inserted proximally in metaphysis, avoid physis.

Beware if fibula intact drifts into varus if fibula fractured drifts into valgus.

If fibula intact asymetrically bend nails to obtain greater elastic recoil of the lateral nail. Alternatively consider two parallel lateral nails, bent in the same direction and introduced into the lateral side of the distal metaphysis.

For both bone fractures increase the bend on the medial nail to resist the strong muscular forces on the lateral side.

Usually rotational stable.

The tibia is triangular in nature with the sides diagonal and the base posterior, as such as the nails are inserted they exert a posterior force leading to recurvatum of the tibia, correct this by rotating the nail tips in a posterior direction.

Consider below knee cast for a few weeks.

Depends on child, fracture configuration leave NWB 6 weeks, remove nails 10-12 weeks.

Femur

Position supine on radiolucent table and do freehand (prefered option) or on fracture table, if started out freehand and need more traction consider using femoral distractor.

Fractures of middle and proximal thirds

Retrograde insertion of 2 C-shaped nails, pre bend 3* diameter of bone for max bend to be at level of fracture site.

Entry point in supracondylar area medial and lateral, 2 cm proximal to the distal femoral physis

Make entry point with an awl, insert nails medial and lateral of similar diameter (40% diameter of canal) and similar curvature to create balanced construct.

Insert both nails up to fracture site, reduce fracture then pass nail across fracture site.

It is better to tap the nails gently with a hammer than rotate them round and round, AVOID winding nails around each other and creating a corkscrew..

Advance to level just above lesser trochanter, just prior to achieving final position cut them off so you can drive them in a little.

Leaving just enough to grab later when removing but not too much to irritate the soft tissue (about 1 cm proud). Don't bend the ends it irritates the soft tissue.

Check rotation prior to finally seating nails.

Distal third

Use antegrade techniquel,

Entry point - lateral surface of femur just below lesser trochanter, using seperate starting points, the second being slightly distal and anterior to the first.

To achieve divergent nails bend 1 nail in a C shape and the second in an S shape.

Postoperatively

For simple femoral fractures - start immediate mobilization, sitting in a chair with the knee flexed down will help control rotation.

Mobilize NWB 2-3 weeks, after this increasing weight bearing as comfort allows.

Unstable fractures, very comminuted fractures might need a more cautious approach, however early knee flexion with the thigh supported will help control rotation.

Adolescents use 4mm nails, no absolute weight limit around 50-60 Kg, possible to do heavier but may need period of protection/ bed rest with split bed knee flexion to avoid nail bending.

Remove metalwork once fracture consolidated around 6 months.

References

Fracture treatment in childhood; Injury; Volume 36, Issue 1, Supplement 1; February 2005

Personal comments

Synthes TENS nail technique manual