Lag-screw fixation for Partial articular fracture of the distal end segment

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Introduction

Short oblique fractures (unicondylar) can be fixed with a lag screw.

For long oblique fractures, fixation with two or three lag screws is recommended.

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

$Lag-screw fixation with two screws of an oblique distal condylar fracture of the proximal phalanx – hand.$

Caveat: changing fracture plane

Hastings and Weiss described a helical/spiral fracture type in which the fracture plane changes between the condylar and metaphyseal zones.

In such a fracture configuration, it is important to observe that all the lag screws are inserted as perpendicularly to the local fracture plane as possible.

Confirm correct fracture planes under direct vision and in different radiographic views.

$Lag-screw fixation with two screws of a helical or spiral oblique distal condylar fracture of the proximal phalanx – hand.$

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.

$Unicondylar depression may lead to angulation of the finger in articular phalangeal fractures – hand.$

Percutaneous vs open reduction and fixation

Percutaneous reduction and fixation may be performed with acute fractures.

The advantages are:

Lowered risk of necrosis
Shorter operation time
Less soft-tissue damage
Faster mobilization

This treatment option needs some skills and experience and special reduction forceps to avoid impingement of swollen soft tissue (atraumatic technique).

If a percutaneous reduction is not achievable, the treatment can be changed to open surgery.

Open reduction and fixation may be used in acute and delayed cases.

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.

Midaxial incision of the proximal interphalangeal joint.

Reduction by ligamentotaxis

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

$Reduction of a partial articular proximal phalanx fracture by ligamentotaxis$

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.

$Indirect reduction of an oblique distal condylar fracture of the distal phalanx – hand.$

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.

$Fracture visualization with a dental pick of an oblique distal condylar fracture of the distal phalanx – hand.$

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.

$Direct reduction of an oblique distal condylar fracture of the proximal phalanx – hand.$

Preliminary K-wire fixation

Long oblique fractures can be preliminarily fixed by inserting a K-wire. Be careful to place it so it will not conflict with later screw placement.

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

$Preliminary K-wire fixation of an oblique distal condylar fracture of the proximal phalanx – hand.$

Screw positioning in a small fragment

If only one screw can be inserted into a small fragment, it will have to be placed within the joint cavity but through the nonarticular face of the condyle, distal to the collateral ligament.

The lateral aspect of the phalangeal head, which is safe for screw placement, can be approached by flexing the proximal interphalangeal (PIP) joint.

A headless cannulated screw is recommended to avoid ligament irritation due to a protruding screw head and eventual joint stiffness.

$Screw positioning in a small fragment of an oblique distal condylar fracture of the proximal phalanx – hand$

Determining screw size

The screw length needs to be adequate for the screw just to penetrate the opposite cortex.

Keep in mind that at the apex of the fragment, the minimal distance between the screw head and the fracture line must be at least equal to the diameter of the screw head. If necessary, a screw of a smaller diameter will have to be chosen.

$Maximal screw head diameter is one-third of the diameter in a small fragment of an oblique distal condylar fracture of the proximal phalanx – hand$

Preparation for drilling

The optimal way to approach the outer surface of the phalangeal head is by flexing the PIP joint and retracting the collateral ligament in a volar direction.

Retraction of the collateral ligament of the proximal interphalangeal joint to access the drill site.

Lag-screw insertion

Insert the headless screw and gently tighten it to compress the fracture.

Headless screw insertion

$Fixation with a headless screw of a fragment of an oblique distal condylar fracture of the proximal phalanx – hand$

Screw positioning in large fragments

In large fragments, all screws can be placed safely proximal to the collateral ligament.

Cortical lag-screw insertion

$Fixation with two cortical screws for a large fragment of an oblique distal condylar fracture of the proximal phalanx – hand$

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.

$Correct versus incorrect screw placement – large fragment of an oblique distal condylar fracture of the proximal phalanx – hand$

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

Screw insertion

Insert the distal screw first.

Alternate tightening of the two lag screws helps avoid tilting the fragment and applies even compression forces over the whole fracture surface.

Confirm anatomical reduction and correct screw placement with an image intensifier.

Check stability of the fixation by passive flexion and extension of the PIP joint and by applying gentle lateral and rotational motion. This will help to determine stability to establish strategies for rehabilitation.

$Lag-screw fixation with two screws of an oblique distal condylar fracture of the proximal phalanx – hand.$

Confirm anatomical reduction of the articular surface and correct screw placement with an image intensifier.

$AP x-ray shows final fixation of a unicondylar partial articular fracture of the 2nd proximal phalangeal head - hand$

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

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.