Lag-screw fixation with a neutralization plate for Partial articular fracture of the distal end segment

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Introduction

Oblique fractures (unicondylar) can be fixed with lag screw(s). If this is not providing sufficient stability, the lag screw(s) must be protected by a plate.

Caveat: These fractures are rare but difficult to treat. There is an increased risk of joint stiffness resulting from these fractures.

For fractures of the phalangeal head, a minicondylar or anatomical plate should be used, because of the angular stability that it provides, although any conventional plate can also be used for protection. The latter has the advantage of being less bulky. This reduces the risk of compromising the gliding of the extensor tendons.

Anatomical plates have the advantage of inserting two or three screws at variable angles into the articular block.

$Lag-screw fixation with a neutralization plate of a partial articular fracture of the proximal phalangeal head$

Anatomical reduction mandatory

Articular fractures must be reduced anatomically. Otherwise, the articular cartilage may be damaged, leading to painful degenerative joint disease and digital deformity.

This illustration shows how even slight unicondylar depression may lead to angulation of the finger.

$Displacement forces in a partial articular fracture of the proximal phalangeal head$

Plate selection

For neutralization or neutralization plating, several plate types may be used:

Conventional straight locking compression plate (LCP); dorsal or lateral
T-plate (adaption plate); dorsal
Strut plate; dorsal
Phalangeal head plate; lateral

The plates may come with or without variable-angle (VA) locking head screws. If an anatomical plate is not available, a conventional minicondylar plate may be used.

The plate selection depends on the fracture pattern and should allow at least two screws in the proximal and distal main fragments.

In this procedure, extrinsic compression and fixation with VA locking-head screws through a phalangeal head plate is shown.

$Selection of plates for fixation of a proximal phalangeal fracture$

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, a midaxial approach to the proximal phalanx is typically used.

Reduction by ligamentotaxis

Often, the fracture can be reduced by applying traction via finger traps.

Index and ring finger in finger traps for ligamentotaxis

Indirect reduction

Reduction starts with traction to restore length.

Exert lateral pressure with your thumb and index finger or with dedicated percutaneous reduction forceps to reduce the fracture.

Confirm reduction with an image intensifier.

$Indirect reduction of a partial articular fracture of the proximal phalangeal head$

Open reduction

If closed reduction is not successful or in a nonacute case, proceed with an open reduction.

Fracture visualization

Use a dental pick to gently explore the fracture site to assess its geometry. The pick can also be used carefully to reduce small fragments. Take great care to avoid comminution of any fragment.

It is important to maintain the vascularity of tiny fragments attached to the collateral ligament, to avoid osteonecrosis.

$Visualization of a partial articular fracture of the proximal phalangeal head with a dental pick$

Direct reduction of large fragments

Small pointed reduction forceps can be used for larger fragments gently to rock the fracture from side to side. Be careful not to apply excessive force, which can lead to fragmentation.

Confirm reduction using image intensification.

Note: Anatomical reduction is important to prevent chronic instability or posttraumatic degenerative joint disease.

$Holding the reduction of a partial articular fracture of the proximal phalangeal head with forceps$

Preliminary K-wire fixation

Insert a preliminary K-wire to stabilize the fracture.

Be careful to place it so it will not conflict with later screw and plate placement.

To avoid conflict of the plate with the insertion of the collateral ligament, the K-wire may be placed in the isometric insertion of the collateral ligament. The notch of the plate may then be aligned to it.

Avoid inserting a K-wire into small fragments, as they are in danger of fragmentation.

$Preliminary K-wire fixation of a partial articular fracture of the proximal phalangeal head and plate positioning$

Lag-screw insertion outside a neutralization plate

If the fracture configuration and plate allow, a lag screw may be inserted outside of the neutralization plate.

The lag screw should be inserted centered on and as perpendicularly to the fracture plane as possible and from the dorsal surface. The direction of the obliquity of the fracture plane dictates the exact position of the lag screw.

Cortical lag-screw insertion

$Lag screw outside of a neutralization for fixation of a partial articular fracture of the proximal phalangeal head$

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

Pitfall: countersinking

Countersinking in the diaphysis should be performed with care as it risks iatrogenic fractures.

Do not countersink the screws in the metaphysis, as its cortex is very thin. If countersinking is attempted, all purchase and compression may be lost due to screw breakthrough.

Countersinking can be performed in the diaphysis not the metaphysis

Screw length pitfalls

Ensure that a screw of the correct length is used.

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

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

Neutralization plate

Apply the neutralization plate depending on the fracture plane and the lag-screw position, either dorsally or laterally.

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

Plate trimming

Adapt the plate length to fit the length of the proximal phalanx. Avoid sharp edges, which may be injurious to the tendons. There should be at least 3 plate holes proximal to the fracture available for fixation in the diaphysis. At least two screws need to be inserted into the diaphysis.

Trimming the plate to fit the length of the proximal phalanx.

Plate positioning

Place the plate slightly dorsal to the midaxial line of the bone, allowing at least two screws in the distal fragment.

The plate notch should be aligned to the K-wire in the isometric insertion of the collateral ligaments.

Keep the plate in place with the atraumatic forceps.

$Lag-screw fixation with a neutralization plate of a partial articular fracture of the proximal phalangeal head – plate application$

Screw insertion

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

Screw insertion in neutral mode

$Lag-screw fixation with a neutralization plate of a partial articular fracture of the proximal phalangeal head – Insertion of first screw$

Fracture compression

The fracture may be compressed with lag screw(s) through the plate if cortical screws are used.

Cortical lag-screw insertion

When using an anatomical plate and VA locking-head screws, apply extrinsic compression with reduction forceps and hold it by inserting the locking-head screw(s) in the articular block.

Locking head screw insertion

Note: Avoid screw protrusion through the far cortex, as ligament injury may result from friction during movement.

$Lag-screw fixation with a neutralization plate of a partial articular fracture of the proximal phalangeal head – insertion of a lag screw through the plate$

Finalizing plate fixation

Insert further screws through the other plate holes.

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).

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

$Lag-screw fixation with a neutralization plate of a partial articular fracture of the proximal phalangeal head – order of screw insertion$

Confirm fracture reduction and stability and implant position with an image intensifier.

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
MCP joint in 90° flexion
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.

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.