Lag-screw fixation with a neutralization plate for Oblique extraarticular fracture of the proximal end segment

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Introduction

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.

For fractures of the condylar metaphysis, a minicondylar or anatomical plate (for the head or base) 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.

$Lag-screw fixation with a neutralization plate of an oblique extraarticular fracture of the proximal phalangeal base$

Fracture plane

Obliquity of the fracture is possible either in the plane visible in the AP view or the lateral view. Always confirm the fracture configuration with views in both planes.

In this procedure, an oblique fracture visible in the lateral view is shown with lag-screw fixation protected with a lateral plate.

$An oblique extraarticular fracture of the proximal phalangeal base$

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
Condylar plate; lateral or dorsal
Phalangeal base plate; lateral or dorsal

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, plate fixation with a condylar plate is shown with the condylar part applied to the phalangeal base.

Selection of plates for application if the proximal phalanx

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 approach is normally used for application of a lateral plate:

Midaxial (lateral) approach to the proximal phalanx

Application of a dorsal plate may require a dorsal approach:

Dorsal approach to the proximal phalanx (after Pratt)

Indirect reduction

Reduction can be achieved manually by traction and flexion.

Confirm reduction clinically and with an image intensifier. If there is shortening of the finger, then there is often malrotation of the fracture.

If the fracture appears stable after reduction, nonoperative treatment can be considered. Confirming reduction with an image intensifier is then essential.

$Closed reduction of an oblique extraarticular fracture of the proximal phalangeal base$

Hold the reduction with reduction forceps designed for a percutaneous technique. Impingement of soft tissues should be avoided.

$Holding the reduction of an oblique extraarticular fracture of the proximal phalangeal base with forceps for percutaneous screw insertion$

Direct reduction

Direct reduction is necessary when the fracture cannot be reduced by traction and flexion or is unstable because of surrounding soft-tissue lesions.

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

Use pointed reduction forceps for direct reduction.

$Holding the reduction of an oblique extraarticular fracture of the proximal phalangeal base with forceps$

Preliminary fixation

Insert a K-wire for provisional fixation.

$Holding the reduction of an oblique extraarticular fracture of the proximal phalangeal base with forceps and a preliminary K-wire$

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.

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

Confirm fracture fixation and stability with an image intensifier.

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

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

$Lag-screw fixation of an oblique extraarticular fracture of the proximal phalangeal base$

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.

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

Pitfall: screw too close to the fracture

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

$Screw placement not close to the fracture apex and with minimal distance to the fracture line equal to the diameter of the screw head$

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 screws are not inserted through these fissure lines.

Screws inserted to avoid passing through short fissures

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 distal 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 proximal fragment.

$Lag-screw fixation with a neutralization plate of an oblique extraarticular fracture of the proximal phalangeal base – application of the plate$

Keep the plate in place with the atraumatic forceps.

$Lag-screw fixation with a neutralization plate of an oblique extraarticular fracture of the proximal phalangeal base – application of the plate$

Screw insertion

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.

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).

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

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

$Lag-screw fixation with a neutralization plate of an oblique extraarticular fracture of the proximal phalangeal base – Order of screw insertion in the plate$

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.