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Diagnosis
Indications
Treatment

Lag-screw fixation

Only avulsion fractures with large fragments can be treated with lag screws.

Drilling the gliding hole through the avulsed fragment in an inside-out technique is recommended. It has the advantage of allowing perfect positioning of the drill hole (perpendicular to the fracture plane and through the center of the fragment).

This fracture type may be associated with metacarpophalangeal (MCP) joint dislocation. In this case, the dislocation must be manipulated, and any interposed soft-tissue structures removed.

Note: Axial traction may permit soft tissue to be interposed. This obstructs relocation and should therefore be avoided.

$Screw fixation of an avulsion fracture of proximal phalanx metacarpophalangeal joint – hand$

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 dorsal approach to the metacarpophalangeal joint is typically used.

Extensor digitorum tendon longitudinal incision and dorsoulnar extensor hood incision

Closed reduction

Dislocation usually occurs as an extension deformity.

This can be reduced by increasing the deformity with some dorsally applied pressure on the proximal phalanges to reduce the joint. This keeps the volar structures in tension and reduced the risk of soft-tissue interposition.

Maneuvers for reduction of a MCP dislocation

Pitfall: Avoid any longitudinal traction as this may cause soft-tissue interposition.

Pitfall of closed reduction of a metacarpophalangeal joint dislocation by traction

Indirect reduction

Reduction is achieved by pulling the finger laterally, opposite to the forces that created the fracture, and into MCP joint flexion, as necessary, to approximate the fragment. The avulsed fragment is pushed into place by the surgeon’s thumb.

$Indirect reduction of an avulsion fracture by surgeon pulling the finger into metacarpophalangeal joint flexion while surgeon’s thumb pushes the avulsed fragment into place$

Open reduction

In displaced fractures, open reduction is often necessary after preparing a gliding hole (see later).

Use small, pointed reduction forceps gently to reduce the fracture from palmar to dorsal and proximal to distal. Application of excessive force can result in fragmentation.

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

$Application of pointed reduction forceps to reduce and hold an avulsion fracture of proximal phalanx - hand$

Stability evaluation

Confirm reduction with an image intensifier and check the joint stability by flexion and extension. This should show congruent movement compared with the adjacent joints.

Planning for screw insertion

The maximal permitted diameter of the screw head is 1/3 of the diameter of the avulsed fragment.

The screw length needs to be adequate for the screw to penetrate and purchase in the opposite cortex.

Maximal screw head diameter is one-third of the diameter of the avulsed fragment

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 insertion

Be sure to insert the screw as a lag screw, with a gliding hole in the near (cis) cortex and a threaded hole in the far (trans) cortex.

Cortical lag-screw insertion

$Determining the diameter of the gliding hole for lag screw insertion in an avulsion fracture of proximal phalanx metacarpophalangeal joint – hand$

Alternative: inside-out technique

Laterally deviate the phalanx in the opposite direction to gain maximal visualization of the joint (open book).

Evaluate the fracture geometry and determine the ideal position of the gliding hole (perpendicular to the fracture plane and through the center of the fragment).

$Visual evaluation of the fracture geometry with laterally deviated phalanx, to determine the gliding hole position for an avulsion fracture of proximal phalanx metacarpophalangeal joint – hand$

Keeping the finger laterally deviated, drill an inside-out gliding hole through the center of the avulsed fragment.

Note: Preserving vascularization: The risk of this procedure is the additional dissection and potential resulting devascularization, which can jeopardize fracture healing.

Drilling an inside-out gliding hole through the center of the avulsed fragment

Reduce the avulsed fragment anatomically, and hold it with pointed reduction forceps, as previously discussed.

$Application of pointed reduction forceps to reduce and hold an avulsion fracture of the proximal phalanx metacarpophalangeal joint – hand$

Insert a 1.3 (1.0) mm drill sleeve into the gliding hole.

Now use a 1.0 (0.8) mm drill bit to drill a threaded hole into the opposite fragment, penetrating the far (trans) cortex.

With the drill sleeve inserted into glide hole, the threaded hole is drilled into the opposite fragment, penetrating the far cortex

Confirm reduction and fixation with an image intensifier.

$An AP x-ray confirms reduction of the avulsion fracture of the proximal phalanx metacarpophalangeal joint – hand$

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

The hand is supported with a dorsal splint for 4 weeks. 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.

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 this period, protect the digit with buddy strapping to the adjacent 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.