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Authors of section


Arnold Besselaar, Daniel Green, Andrew Howard

Executive Editor

James Hunter

General Editor

Fergal Monsell

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ESIN (antegrade)

1. General considerations

The ESIN method involves closed reduction and internal fixation with elastic nails.

It is difficult to treat shaft fractures of the distal third with retrograde nail insertion as the nail entry sites are too close to the fracture and the configuration of the nails does not produce sufficient stability.

Using an antegrade nail construct will provide sufficient stability in these fractures.

Final construct

2. Instruments and implants

Instrument set for ESIN

  • 2.5–4.0 mm elastic nails
  • Awl or drill
  • Inserter
  • Hammer
  • End caps and insertion device
  • Impactor
  • Extraction plier
  • Nail cutter
Instrument set for ESIN

The end cutter is useful to avoid sharp ends and soft-tissue irritation.

End cutter

Nail diameter

For optimal stability, the nail diameter should be between 33% and 40% of the narrowest part (isthmus) of the medullary canal.

Both nails need to be of the same diameter.

Pearl: To estimate the optimal nail diameter place the selected nail on the leg parallel to the bone and check with an image intensifier (as shown in the illustration).
For later precontouring mark the level of the fracture site on the nail.
Nail diameter should be 33–40% of narrowest part of medullary canal.

3. Patient preparation and approach

Patient positioning

Place the patient in a supine position on a traction table or radiolucent fracture table.

The radiolucent fracture table has the advantage that the leg can be freely manipulated during the procedure. Muscle forces can be neutralized by flexing the knee with a support underneath.

When positioning the patient check the rotational alignment of the uninjured femur.

Supine patient position


Expose the bone at the entry points.

Approach to the entry points

4. Opening the canal

Position of entry points

The usual entry points are 0.5–1 cm distal to the greater trochanteric growth plate.

Entry points should be at least 2 cm apart in the axial plane and at least 1 cm apart in the lateral plane. If they are too close, the cortex may split during the insertion of the nails.

There is a lower risk of iatrogenic fracture if both entry points are made in the metaphyseal bone proximal to the lesser trochanter. Alternatives include entry points in the lateral aspect of the greater trochanter.

Opening the proximal entry point

Proximal entry point

Place the awl or drill directly onto the bone and perforate the near cortex, under direct vision, perpendicular to the bone.

Do not hammer the awl to avoid perforation of the far cortex.

When the medullary canal is entered, lower the awl or drill 45° to the shaft axis. Advance it with oscillating movements to produce an oblique canal.

Opening the proximal entry point

Second entry point

Enter the medullary canal at the distal entry point with an identical technique.

Opening the distal entry point

5. Nail insertion

Decide whether the crossing point of the nails is to be proximal or distal to the fracture site.

Crossing the nails at the level of the fracture must be avoided.

Precontour both nails in the distal third with the apex at the predetermined level.

The maximum nail bend should be at the level of the fracture about three times the diameter of the medullary canal.

Precontouring the nails

Insert the nail through the proximal entry point into the intramedullary canal and advance it towards the fracture site with an oscillating maneuver.

Insertion of the first nail through the proximal entry point
Pearl: Insert the nail with the tip perpendicular to the shaft axis until the far cortex is felt. Rotate the nail 180° and advance it using the curved side of the tip.
If the tip is stuck in the far cortex and cannot be advanced, remove the nail and bend the tip to give a slightly more pronounced curvature.
Pearl: A short working length (3–5 cm) between the entry point and the inserter improves control of the nail during insertion.
Pearl for nail insertion

Insert the second nail into the distal entry point and advance it towards the fracture zone.

Insertion of second nail

Once it has good contact with the opposite cortex, with the tip having advanced about two-thirds distally in the medullary canal, the contour of the nail is changed to an S-shape with the following maneuver:

  1. Rotate the nail 180°.
  2. Bend the proximal portion of the nail, which is outside the bone, in the opposite direction to the previous bend.
  3. Apply a constant bending force whilst inserting the nail.

This produces an S-shape, which will provide contact with the lateral cortex at the fracture site and with the medial cortex of the proximal third of the femoral shaft.

Contouring the second nail in an S-shape
Pitfall: Make sure that the second nail has not crossed the first more than once to avoid the corkscrew phenomenon.
If this happens reinsert a new nail.
Pitfall: corkscrew phenomenon

6. Distal fragment advancement

Advance the first nail past the fracture zone and into the distal fragment with an oscillating maneuver.

Advance the second nail in a similar manner.

Advancing the nails past the fracture site into the distal fragment

If it is difficult to advance either nail while it is positioned against the cortex, rotate the tip towards the center of the bone and advance it across the fracture zone.

Reorientation of nail tip to advance the nail across the fracture

If this is unsuccessful use a bone hook or Steinmann pin through a small incision.

Reduction with Steinmann pin

Open reduction (through a limited lateral approach) may be necessary if closed reduction cannot be achieved.

Open reduction through a limited lateral approach

Advancing the nails through a floating segment

Advance the first nail past the fracture site through the floating segment and into the distal fragment with gentle hammer blows.

This avoids rotation and splitting of the middle segment.

Advance the second nail in an identical manner.

Pitfall: Iatrogenic fractures of a floating segment reduce axial stability and end caps are recommended if this occurs.
Advancing the nails through a floating segment

Final reduction

Once the nail has crossed the fracture, rotate the nail tip to return to the initial position to achieve satisfactory reduction.

If necessary other reduction tools may also be used.

Rotation of nail tip back to initial position

Wedge fragments

A wedge fragment does not need to be reduced anatomically.

If the fracture is axially unstable, end caps are recommended.

Wedge fragments

Assessment of rotational alignment

Confirm rotational alignment of the femur clinically and radiographically. This can be done by:

  • Fluoroscopy of the fracture site (matching shaft diameters)
  • Comparing internal and external rotation to the contralateral side (consider preparing and draping the uninjured side)
  • Fluoroscopy of proximal femur (lesser trochanter profile)

For more detail see the additional material on assessment of rotation.

7. Final seating

Advance the nails and impact them medially and laterally into their respective condylar regions.

Align the nail tips so that they diverge.

Final seating of nails with their tips in the condylar regions

If more stability is necessary and/or the fracture is very distal, the physis can be perforated with the nails.

A single pass of a smooth nail across a growth plate is unlikely to produce a growth arrest.

Perforation of physis to gain more stability

8. Cutting the nails

Cut the nails with the dedicated nail cutter.

Cutting the nails with the dedicated nail cutter

If this is not available, withdraw the nails far enough to apply the nail cutter.

Reinsert the nails so at least 1 cm of the nail remains outside the bone.

Retracting the nails for cutting with common cutter

The ESIN impactor can be used to ensure that an appropriate length of the nail remains outside the bone to allow application of an end cap.

Use of ESIN impactor

End caps

End caps can be used to increase axial stability.

They will also protect soft tissues.

Pearl: Bend the nail to just elevate it from the bone to facilitate end-cap insertion.

Insert the end cap over the cut end of the nail and screw it into the metaphysis.

Insertion of end caps

Confirm that the end cap is covering the nail and fixed to the bone with image intensification.

Final nail position with end caps

9. Final assessment

Check the range of internal and external rotation of the leg and compare with the contralateral limb.

Obtain final AP and lateral fluoroscopic views.

Checking the range of internal and external leg rotation

10. Aftercare

Immediate postoperative care

The patient should get out of bed and begin ambulation with crutches on the first postoperative day.

In most cases the postoperative protocol will be protected weight bearing for the first 4 weeks.

Ambulation with crutches on first postoperative day


Routine pain medication is prescribed for 3–5 days postoperatively.

Neurovascular examination

The patient should be examined frequently, to exclude distal neurovascular compromise.

Compartment syndrome, although rare, should be considered in the presence of severe swelling, increasing pain, and changes to neurovascular signs.

Discharge care

Discharge from hospital follows local practice and is usually possible after 1–3 days.


The patient should ambulate with crutches and begin knee range-of-motion exercises.


Clinical and radiological follow-up is usually undertaken every 2–8 weeks until radiographic healing and restoration of function.

Clinical assessment of leg length and alignment is recommended at one-year.

Clinical assessment of leg length uses a tape measure from the ASIS to the medial malleolus.

Clinical assessment of leg length with tape measure form ASIS to medial malleolus

If there is any concern about leg-length discrepancy or malalignment, long-leg x-rays are recommended.

Leg length is measured from the femoral head to the ankle joint.

Leg length measured in a long-leg x-ray from femoral head to ankle joint

Implant removal

If the patient develops symptoms related to the implant, it can be removed once the fracture is completely healed, usually 6–12 months following injury.

11. Clinical case

AP and lateral view of a multifragmentary spiral fracture

AP and lateral view x-ray of fracture

AP and oblique views of hip (top) and lateral and AP view of knee (bottom) three-month post injury

X-rays three-month post injury

Long-leg x-ray for radiological assessment of leg length one-year post injury

Long-leg x-ray one-year post injury