Lag-screw fixation with a neutralization plate

In short oblique fractures, only one lag screw can be inserted. This is insufficient to produce enough stability, and the lag screw must be protected by a plate. A neutralization plate may also be indicated if screw fixation alone is not providing sufficient stability, eg, in poor quality bone.

As the screw should be inserted perpendicularly to the fracture plane, in most cases, it has to be inserted independently of the plate.

For neutralization plating extraarticular and articular fractures, a T-, Y- or L-shaped adaption plate may be used, as it allows for two screws in the short fragments.

The plate selection (1.5–2.0 mm) depends on the size of the bone, the fracture pattern and should allow at least two screws in the proximal and distal main fragments.

The plate is available as a conventional compression plate or with variable-angle (VA) locking-head screws.

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

For this procedure, the following approaches may be used:

• Dorsal approach to the metacarpals

In the 2nd metacarpal, a radial approach may be used. In the 5th metacarpal, an ulnar approach may be used.

Reduce the fracture with longitudinal traction on the finger and pressure from a periosteal elevator or a dental pick.

Secure the reduction with pointed reduction forceps and confirm reduction with an image intensifier. Ensure the reduction forceps do not conflict with the planned screw position.

It is essential to confirm that the apex of each fracture fragment has been properly reduced.

Alternatively, special reduction forceps designed for percutaneous fixation may be used.

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. Flexing the MCP joints while preventing overlap of the fingers will reduce rotational displacement.

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.

Insert the lag screw in the center of the fracture and perpendicular to the fracture plane. Carefully tighten the screw.

• Cortical lag-screw insertion

The fracture is now compressed. The reduction forceps may now be removed.

Confirm reduction and correct screw position with an image intensifier.

The exact size of the diameter of the screws used will be determined by the fragment size and the fracture configuration.

The various gliding and thread hole drill sizes for different screws are illustrated here.

Cut the plate to the correct length to allow two screws to be inserted into the diaphyseal fragment.

Contour the plate perfectly to the bone surface. Since the plate will not exert axial compression, overbending is not necessary.

Place the plate dorsally to the bone and as close as possible to the articular surface.

Keep the plate in place with the atraumatic forceps.

Start with insertion of a cortical screw in the oblong whole. This will allow for further adjustment of the plate.

Insert VA locking-head screws through the other plate holes.

• Locking head screw insertion
• Screw insertion in neutral mode

Confirm correct rotational alignment of the finger again.

Insert at least two screws in the articular block first. Take care not to violate the joint surface.

Finalize the plate fixation with introduction of the remaining screw(s).

Confirm reduction and implant position with an image intensifier.

Cover the plate with periosteum to avoid adhesion between the tendon and the implant leading to limited finger movement.

Confirm correct rotational alignment by clinical examination.

Confirm anatomical reduction and correct placement of implants in AP, lateral, and oblique views.

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
• Metacarpophalangeal (MCP) joint in 90° flexion
• Proximal interphalangeal (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.

The implants may need to be removed in cases of soft-tissue irritation.

In case of joint stiffness or tendon adhesion restricting finger movement, arthrolysis or tenolysis may become necessary. In these circumstances, the implants can be removed at the same time.