The ESIN method involves closed reduction and internal fixation with elastic nails.
It is difficult to treat shaft fractures of the middle and proximal third with antegrade nail insertion as the nail entry sites are close to the fracture and the configuration of the nails does not produce sufficient stability.
Using a retrograde nail construct will provide sufficient stability in these fractures.
2. Instruments and implants
Instrument set for ESIN
2.5–4.0 mm elastic nails
Awl or drill
End caps and insertion device
The end cutter is useful to avoid sharp ends and soft-tissue irritation.
The F-tool can be helpful to align the femur.
For optimal stability, the nail diameter should be between 33% and 40% of the narrowest part (isthmus) of the medullary canal.
A larger size of the nail may be required for increased stability.
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.
3. Patient preparation and approach
Place the patient in a supine position on a radiolucent fracture table with or without traction.
When positioning the patient check the rotational alignment of the uninjured femur.
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.
5. Nail insertion
In multifragmentary fractures the contouring should be gentle C-shaped over the whole length of the bone.
Insert the first nail through the lateral entry point into the intramedullary canal and advance it towards the fracture site with an oscillating maneuver.
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.
Insert the second nail into the medial entry point in an identical manner.
Pearl: Use a T-handle on the medial nail to act as a joystick reduction tool. This also avoids changing the inserter from one nail to the other.
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.
6. Proximal fragment advancement
Advance the first nail past the fracture zone and into the distal fragment with an oscillating maneuver.
Advance the second nail in the same way.
Use the nails as joysticks to reduce the main fragments.
If necessary, use an F-tool to align both fragments.
If this is unsuccessful use a bone hook or Steinmann pin through a small incision.
Open reduction (through a limited lateral approach) may be necessary if closed reduction cannot be achieved.
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.
A wedge fragment does not need to be reduced anatomically.
If it the fracture is axially unstable, end caps are recommended.
Assessment of rotational alignment
Confirm rotational alignment of the femur clinically and radiographically before fixing the second fragment. 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 as well)
Fluoroscopy of proximal femur (lesser trochanter profile)