Intramedullary screw fixation

Transverse shaft fractures may be fixed with an intramedullary headless screw (2.4 or 3.0 mm), either ante- or retrogradely. The antegrade insertion is more challenging and needs some experience.

This screw acts like an intramedullary nail.

In this procedure, the retrograde insertion is shown. For the antegrade insertion, see:

• Antegrade intramedullary screw fixation

For further reading on intramedullary screw fixation of proximal phalangeal fractures, see also the dedicated section in:

• References on management of proximal phalangeal injuries

To allow the screw head to be fully buried in the subchondral bone, the fracture line should be at least 6 mm away from the joint surface.

The diameter at the isthmus of the intramedullary canal should be at least 3 mm wide in AP and lateral views.

To allow for fracture compression, the length of the screw should be long enough so that the threads at the tip only engage in the far fragment.

To achieve optimal stabilization, the screw should be long enough and with a diameter filling the intramedullary canal.

Place the patient supine with the arm on a radiolucent hand table.

Manually correct any malrotation with the proximal interphalangeal (PIP) joint fully flexed.

Confirm correct rotational alignment.

If closed reduction is not successful or in a nonacute case, proceed with an open reduction and consider another fixation technique.

When indirect reduction is not possible, this is usually due to interposition of parts of the extensor apparatus.

The entry point for retrograde insertion is positioned dorsally to the center of the articular surface.

Insert the guide wire percutaneously through the central tendon parallel to the dorsal cortical lines of the phalanx under image intensification.

At this stage, it is advisable to check the alignment and rotational correction by moving the finger through a range of motion.

Rotational alignment can only be judged with flexed metacarpophalangeal (MCP) joints. The fingertips should all point to the scaphoid.

Malrotation may manifest by an overlap of the flexed finger over its neighbor. Subtle rotational malalignments can often be judged by a tilt of the leading edge of the fingernail when the fingers are viewed end-on.

If the patient is conscious and the regional anesthesia still allows active movement, the patient can be asked to extend and flex the finger.

Any malrotation is corrected by direct manipulation and later fixed.

Under general anesthesia, the tenodesis effect is used, with the surgeon fully flexing the wrist to produce extension of the fingers and fully extending the wrist to cause flexion of the fingers.

Alternatively, the surgeon can exert pressure against the muscle bellies of the proximal forearm to cause passive flexion of the fingers.

Confirm fracture fixation and stability with an image intensifier.

Perform a small transverse incision around the guide wire insertion and a longitudinal split of the central band of the extensor tendon. This will expose the head of the proximal phalanx and protect the soft tissues during screw insertion.

Select a screw with the appropriate diameter and length using the depth gauge provided. The thread of the tip should engage the isthmus distal to the fracture line.

Insert the screw over the guide wire until the head is subchondral.

Confirm reduction and correct screw placement with an image intensifier.

The aftercare can be divided into four phases of healing:

• Inflammatory phase (week 1–3)
• Early repair phase (week 4–6)
• Late repair and early tissue remodeling phase (week 7–12)
• Remodeling and reintegration phase (week 13 onwards)

Full details on each phase can be found here.

If there is swelling, the hand is supported with a dorsal splint for a week. This would allow for finger movement and help with pain and edema control. The arm should be actively elevated to help reduce the swelling.

The hand should be splinted in an intrinsic plus (Edinburgh) position:

• Neutral wrist position or up to 15° extension
• MCP joint in 90° flexion
• PIP joint in extension

The reason for splinting the MCP joint in flexion is to maintain its collateral ligament at maximal length, avoiding scar contraction.

PIP joint extension in this position also maintains the length of the volar plate.

After subsided swelling, protect the digit with buddy strapping to a neighboring finger to neutralize lateral forces on the finger.

To prevent joint stiffness, the patient should be instructed to begin active motion (flexion and extension) immediately after surgery.

See the patient after 5 and 10 days of surgery.

Intramedullary screws should not be removed as this may result in cartilage damage.