Executive Editor: Chris Colton

Authors: Fiesky Nuñez, Renato Fricker, Matej Kastelec, Terry Axelrod

Middle phalanx - PIP joint - dorsal avulsion fracture

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Glossary

1 Principles top

All of these are characterized by detachment of the central slip of the extensor apparatus. They are considered as acute ... enlarge

Lesion classification

There is a number of lesions produced by a hyperflexion mechanism.
All of these are characterized by detachment of the central slip of the extensor apparatus. They are considered as acute boutonnière injuries.

Lesions without dislocation

  1. Hyperflexion with detachment of the central slip (no fracture)
  2. Simple avulsion fracture of the central slip with a small nonarticular fragment
  3. Simple avulsion fracture of the central slip with a larger articular fragment

Sometimes, lesions such as these are considered minor injuries by traumatologists, and often they are confused with simple ... enlarge

Sometimes, lesions such as these are considered minor injuries by traumatologists, and often they are confused with simple ligament sprains. However, if not treated early and correctly, boutonnière deformity, which is difficult to treat at a later stage, is a common consequence.


If palmar dislocation of the PIP joint is present, a rupture of the collateral ligament and detachment of the central slip ... enlarge

Lesions with palmar dislocation
If palmar dislocation of the PIP joint is present, a rupture of the collateral ligament and detachment of the central slip are involved. In injuries of this kind, a swan-neck deformity is present, and the finger can not be flexed.

Lesions with dislocations

  1. Detachment of the central slip without a fracture
  2. Avulsion fracture of the central slip with a small nonarticular fragment
  3. Avulsion fracture of the central slip with a larger articular fragment

Early diagnosis of injuries without dislocation is important. This is not always easy due to the swelling and often ... enlarge

Undislocated lesions: Early diagnosis by Stark maneuver

Early diagnosis of injuries without dislocation is important. This is not always easy due to the swelling and often inconclusive x-rays.

Keep the PIP joint hyperextended. Passively flex the DIP joint.
If passive movement of the DIP joint is limited, this is a strong indication for the presence of a central slip detachment.
Compare with the uninjured hand.


In order to recognize detachment of the central slip, ask the patient to extend the PIP joint with the MP joint in ... enlarge

Recognizing detachment of the central slip

In order to recognize detachment of the central slip, ask the patient to extend the PIP joint with the MP joint in hyperextension.
If the PIP joint can be fully extended in this position, the central slip is still attached, and nonoperative treatment may be indicated.

Pitfall: MP joint not hyperextended
If the MP joint is not hyperextended, extension of the PIP joint may still be possible, even with a detached central slip. In this case, the intrinsic muscles will extend the joint.


These injuries are commonly caused by sporting accidents, often in ball games such as cricket, volleyball, basketball, etc. enlarge

Mechanism of the injury

These injuries are commonly caused by sporting accidents, often in ball games such as cricket, volleyball, basketball, etc.
Typically, hyperflexion of the finger causes an avulsion lesion of the central slip.
Often, in addition to hyperflexion, impact on the finger tips causes longitudinal compression forces on the middle phalanx towards the proximal phalanx, leading to an additional impaction fracture.

View animation


When the central slip is detached, the lateral bands are palmarly displaced and pull the DIP joint into hyperextension. enlarge

Deforming forces

Boutonnière deformity
When the central slip is detached, the lateral bands are palmarly displaced and pull the DIP joint into hyperextension.
The flexor digitorum superficialis (FDS) pulls proximally on the middle phalanx, forcing the PIP joint into flexion.

Swan-neck type deformity
If the middle phalanx is palmarly dislocated at the PIP joint by the energy of the trauma, the flexor digitorum profundus (FDP) pulls the DIP joint into flexion.

2 Indications top

The majority of these lesions can be treated by closed reduction and splinting for 6 weeks, leaving the DIP joint free ... enlarge

Nonoperative treatment

The majority of these lesions can be treated by closed reduction and splinting for 6 weeks, leaving the DIP joint free for active mobilization. Encourage the patient actively to flex and extend the DIP joint, which allows healing of the lateral band in the right position.


An avulsion fracture of the central slip can usually be reduced by full extension. enlarge

Large fragment avulsion fracture

An avulsion fracture of the central slip can usually be reduced by full extension. Confirm using image intensification.


If the fracture does not reduce, usually this is an indication of soft-tissue interposition. In such cases, surgical ... enlarge

If the fracture does not reduce, usually this is an indication of soft-tissue interposition. In such cases, surgical treatment is indicated.
Possible treatments include lag screw fixation, or percutaneous K-wire fixation. Tension-band wiring is another option.

3 Reduction top

Flex the PIP joint. In order to gain a better view of the fracture and the joint, use a syringe to clear out blood clot with ... enlarge

Clean the fracture site

Flex the PIP joint. In order to gain a better view of the fracture and the joint, use a syringe to clear out blood clot with a jet of Ringer lactate.
Often the presence of comminution is not apparent from the x-rays, and can only be determined under direct vision.
Use a dental pick carefully to free interposed tissues, and to remove blood clot and other debris.


Put manual pressure on the palmar side of the middle phalanx. Complete the reduction with help of a dental pick. enlarge

Reduce the fracture

Extend the PIP joint and apply traction. Put manual pressure on the palmar side of the middle phalanx.
Complete the reduction with help of a dental pick.

4 Wire fixation top

Use a drill guide and a 1.5 mm drill bit to make a transverse hole in the metaphysis of the middle phalanx. enlarge

Prepare transverse hole

Use a drill guide and a 1.5 mm drill bit to make a transverse hole in the metaphysis of the middle phalanx.


The location of the drill hole should be the same distance from the fracture line as the avulsed fragment’s length ... enlarge

The location of the drill hole should be the same distance from the fracture line as the avulsed fragment’s length (usually approximately 1 cm). This will help the wires to cross above the fracture line, resulting in optimal force distribution.


As the middle phalanx has a comparatively flat dorsal surface, it is sometimes difficult to drill a transverse hole. enlarge

Alternative: Insert screw

As the middle phalanx has a comparatively flat dorsal surface, it is sometimes difficult to drill a transverse hole.
As an alternative for anchoring the cerclage wire, a screw can be inserted approximately 1 cm from the fracture line. Follow standard screw inserting technique, including drilling and measuring. The screw must engage the far cortex. The screw head must protrude just enough for the wire to find anchorage.


Pass 0.6 mm stainless steel wire through the hole. Alternatively, a 4.0 nonabsorbable multifilament suture can be used, ... enlarge

Pass wire through the hole

Pass 0.6 mm stainless steel wire through the hole. Alternatively, a 4.0 nonabsorbable multifilament suture can be used, double-mounted on a straight needle.


Do not place the wire on top of the central slip, as this may cause necrosis by pressure. enlarge

Pass wire through central slip

Pass the wire through the central slip, as close as possible to its insertion into the bone. A 21 hypodermic needle can be used to pass the wire through the tendon as close as possible to the bony fragment.
Do not place the wire on top of the central slip, as this may cause necrosis by pressure.


Depending on the fracture geometry, the avulsed fragment may tilt when the wire is tightened. If this is the case, and the ... enlarge

Pitfall: tilting

Depending on the fracture geometry, the avulsed fragment may tilt when the wire is tightened.
If this is the case, and the fracture size allows it, one or two 0.6 mm K-wires can be inserted to secure the reduction.


If the avulsed fragment is large enough, two 0.6 mm K-wires can be inserted to secure it to the main fragment of the middle ... enlarge

Alternative: use K-wires in avulsed fragment

If the avulsed fragment is large enough, two 0.6 mm K-wires can be inserted to secure it to the main fragment of the middle phalanx. These K-wires can then be used to anchor the tension band wire on the avulsed fragment.
Check palmar protrusion of the K-wires under image intensification. Then retract the K-wires by about 2 mm, bend them through 180 degrees, cut them and impact them into the bone. The K-wires must engage the far cortex, but must not protrude into the flexor tendon tunnel, in order to avoid irritating the tendons.

The K-wires will prevent tilting of the fragment on tightening of the wire.


Do not overtighten the wire, as the central slip may be cut, or the bone penetrated, loosening the fixation. enlarge

Tighten the wire

Now make a figure of eight and twist the wire. Check reduction using image intensification. Tighten the wire.

Pitfall: overtightening
Do not overtighten the wire, as the central slip may be cut, or the bone penetrated, loosening the fixation.


This drawing shows the alternative completed fixation with a screw anchor. enlarge

Alternative: screw technique

This drawing shows the alternative completed fixation with a screw anchor.


Cut the wire and bend it along the phalanx in order to avoid soft-tissue irritation. enlarge

Avoid soft-tissue irritation

Cut the wire and bend it along the phalanx in order to avoid soft-tissue irritation.
When tightening the wire, ensure that both ends are twisted around each other rather than twisting one end around the other straight end.
This is achieved by pulling the wire twist to tighten it and then twisting further to take up the slack produced.

5 Alternative fixation: suture anchors top

In very small fragments suture anchors may be a good alternative, as the technique is easy and faster. enlarge

Indication

In very small fragments suture anchors may be a good alternative, as the technique is easy and faster.
Depending on the size of the fragment, two anchors can be used.


Use an anchor that has approximately the same breadth as the avulsed fragment. enlarge

Fixation

Use an anchor that has approximately the same breadth as the avulsed fragment.
Use 4.0 multifilament nonabsorbable sutures. Wrap the sutures around the avulsed fragment. Tighten the sutures.


If the size of the fragment allows, two suture anchors can be used. enlarge

Alternative: fixation with 2 suture anchors

If the size of the fragment allows, two suture anchors can be used.
Choose anchors corresponding to the breadth of the fracture. If the anchors are too small, reduction will be compromised by the sutures interposing.

6 K-wire for stabilization top

If there is any doubt about the stability of the fixation, insert a K-wire obliquely crossing the PIP joint. enlarge

Check stability of the fixation.

If there is any doubt about the stability of the fixation, insert a K-wire obliquely crossing the PIP joint.
The K-wire can be removed after 2-3 weeks.

v1.0 2008-11-08