Lag-screw and plate fixation for Wedge or multifragmentary fracture of the diaphysis

Home
Skeleton
Diagnosis
Indications
Treatment

Principles

A wedge fragment may be fixed to both end segments with lag screws if the fractures are sufficiently oblique and the wedge fragment large enough. A dorsal neutralization plate is then applied to protect the lag screws.

This technique is useful to gain more stability if only nonlocking plates are available.

If the fracture morphology allows only one lag screw, fracture stabilization is completed with a dorsal bridge plate.

Smaller lag screws (1.0 or 1.3 cortical) should be used to avoid vascular compromise and further fragmentation. In doubt, bridge plating should be considered.

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft$

Plate selection

Select a plate (1.5–2.0 mm) according to the size of the bone, fracture geometry, and surgeon’s preference.

The plate length should allow for at least two screws in each main fragment.

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

When the fracture extends into the metaphysis, a T-, Y- or L-shaped adaption plate or an anatomical plate may be used, as it allows for two screws in the short fragments.

$Plate selection for fixation of metacarpal fractures$

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

Patient positioned 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.

Gaining length

Length can be gained by traction applied manually, by a finger trap, or with pointed reduction forceps.

$Multifragmentary fracture of the metacarpal shaft – Reduction by traction$

Reducing rotation and angulation

Manipulate the fragments with pointed reduction forceps to reduce rotation and restore correct angulation.

Pitfall: excessive pressure may cause fracture comminution.

$Multifragmentary fracture of the metacarpal shaft – Holding the reduction with forceps$

Direct reduction

Secure the reduction of the more oblique fracture part with pointed reduction forceps and confirm 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.

$Multifragmentary fracture of the metacarpal shaft – Holding the reduction with forceps$

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

$Multifragmentary fracture of the metacarpal shaft – Holding the reduction with forceps designed for percutaneous fixation$

Insertion of the first lag screw

Fix the wedge fragment to one of the main fragments, preferably with the longer oblique fracture line, with a lag screw in the center of the fracture area and perpendicular to the fracture plane. In a long oblique or spiral fracture, a second screw may be used.

Cortical lag-screw insertion

Confirm reduction and correct screw position with an image intensifier.

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft – Insertion of first lag screw$

Screw size selection

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.

Screw sizes of the diameters and thread hole drill sizes

Screw length pitfalls

Ensure that a screw of the correct length is used.

Too short screws do not have enough threads to engage the far cortex properly. This problem increases when self-tapping screws are used due to the geometry of their tips.
Too long screws endanger the soft tissues, especially tendons and neurovascular structures. With self-tapping screws, the sharp cutting flutes are especially dangerous, and great care has to be taken that the flutes do not protrude beyond the cortical surface.

$Correct screw length for fracture fixation means screws should not be too long or too short.$

Pitfall: screw too close to the fracture

Do not insert the screw too close to the fragment apex. A minimal distance from the fracture line, equal to the head diameter, must be observed.

$Lag screw fixation with neutralization plate of an oblique metacarpal fracture – screw distance to the fracture line$

Pitfall: beware of fissure lines

Often there are short fissure lines that are not apparent on the x-rays. Check for these under direct vision and ensure the screw is not inserted through these fissure lines.

$Lag screw fixation with neutralization plate of an oblique metacarpal fracture – fissure lines$

If the fracture pattern allows, a second lag screw may be inserted through the wedge fragment into the other main fragment. Ensure that there is enough distance between the two screw heads.

Cortical lag-screw insertion

This construct needs addition of a protection/neutralization plate to improve stability of the fixation.

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft – insertion of lag screws$

Identifying malrotation

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.

Fingertips of flexed fingers should point to the scaphoid. Malrotation manifests by overlap of a flexed finger over its neighbors.

Using the tenodesis effect when under anesthesia

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.

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.

Surgeon exerting pressure against the muscle bellies of the proximal forearm to cause passive flexion of the fingers

Apply the neutralization plate dorsally.

Insert at least two screws proximally and distally to the fracture in neutral mode.

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

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft – order of screw insertion$

If the other fracture part is not allowing for a further lag-screw fixation or according to surgeon’s preference, the fixation may be finalized with a compression plate.

Place the plate dorsally onto the metacarpal.

If the plate is perfectly contoured to follow the geometry of the concavity of the metacarpal bone, tightening the screws will result in a gap in the opposite cortex.

The solution to this is slightly to overbend the plate so that when the plate exerts axial compression, the compression occurs evenly over the whole fracture surface.

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft – compression plating$

Pitfall: If the plate is not properly aligned on the dorsal surface of the metacarpal, the screws may not penetrate the medullary canal and may not have sufficient purchase. Secondary fractures may result.

Screw insertion during plate application to a metacarpal bone

Apply the compression plate according to standard techniques.

After inserting the second screw, check the rotational alignment again.

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft - Compression plating$

Insert the remaining screws in neutral mode.

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

$Lag-screw and plate fixation of a multifragmentary fracture of the metacarpal shaft - Compression plating$

Clinically confirm correct rotational alignment again.

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

Postoperative phases

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.

Postoperative treatment

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

Dorsal splint to treat a dislocation of the proximal interphalangeal joint

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.

The metacarpophalangeal joint in flexion maintains the collateral ligament at maximal length and the proximal interphalangeal in extension 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.

Buddy strapping avoiding direct skin contact with adjacent fingers as conservative treatment

Functional exercises

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

Follow-up

See the patient after 5 and 10 days of surgery.

Implant removal

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.