Executive Editor: Chris Colton

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

Distal phalanx Palmar avulsion

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Glossary

1 Principles top

The distal phalanx is divided into three anatomical parts: most proximally, the metaphysis, followed by the diaphysis ... enlarge

Anatomy

The distal phalanx is divided into three anatomical parts: most proximally, the metaphysis, followed by the diaphysis (“waist”), and finally the ungual tuberosity (“tuft”).

The base of the distal phalanx has a prominent crest on the dorsal aspect with the insertion of the terminal extensor tendon. The tendon is adherent to the joint capsule.
On the palmar surface is the insertion of the flexor digitorum profundus tendon. This is adherent to the volar plate and to the periosteum.
The flexor tendon occupies the whole width of the base of the distal phalanx. It is made up of 2 different fibers. The superficial fibers attach to the lateral aspects of the phalanx. The deep fibers run centrally and attach more distal in the palmar aspect of the phalanx.
The volar plate is very flexible, allowing hyperextension of the DIP joint to allow pulp-to-pulp pinching, which is unique to humans. This flexibility is also facilitated by the absence of check reins, which might be attached to the middle phalanx.


The vincular arteries, essential for vascularization of the flexor tendon, are at risk in palmar avulsion injuries. enlarge

The vincular arteries, essential for vascularization of the flexor tendon, are at risk in palmar avulsion injuries. If the flexor tendon retracts, they are disrupted. This negatively affects the healing process.


Tendon rupture at its insertion at the distal phalanx, without a bony fragment. enlarge

Classification

A useful classification for this type of injury comes from Leddy and Packer.

Type I
Tendon rupture at its insertion at the distal phalanx, without a bony fragment. The tendon is retracted, often into the palm, where it can be palpated. The patient feels some tenderness or pain where the tendon is located.
The vincular arteries are ruptured, impairing the vascularity of the flexor tendon.

Success of treatment of this injury relies heavily on

  • accuracy of diagnosis
  • rapid surgical intervention

 

The flexor digitorum profundus (FDP) tendon must be repositioned and reinserted. This is not possible after 10 days following the injury because of:

  • tendon swelling
  • collagen regeneration
  • Muscle contracture

Reinsertion after this period will lead to a significant flexion contracture of the finger (myostatic contracture).


Tiny fracture fragment. This is usually not easy to see in an x-ray, but may be palpated. enlarge

Type II
Tiny fracture fragment. This is usually not easy to see in an x-ray, but may be palpated.

The tendon is retracted to the PIP joint and is prevented from retracting further by the bony fragment catching in the bifurcation of the superficialis tendon (as shown in the drawing). The long vincular artery remains intact.


FDP avulsion fracture with a large fragment. enlarge

Type III
FDP avulsion fracture with a large fragment.
This fragment remains minimally displaced because of the volar plate attachment, the collateral ligament, and the IV annular pulley.


Palmar avulsion injury

An avulsion injury destroys the synergistic balance of the pull exerted by flexor and extensor tendons. The continuity of the flexor tendon is lost. This results in inability to flex the DIP joint.
Avulsion fractures of the flexor digitorum profundus tendon are uncommon, but particularly disabling. The ring finger is the digit most commonly affected.


These injuries are commonly caused by sporting accidents. enlarge

Mechanism of the injury

These injuries are commonly caused by sporting accidents.
Typically, hyperextension and a strong pull on the flexor tendon causes this fracture, as happens when the finger gets caught while tackling a sporting adversary.


Indication for operative treatment with a K-wire

The main indication for surgery of small palmar avulsion fractures of the proximal distal phalanx is displacement of the fragment.

Two possibilities exist:

  • minor displacement
  • displaced to the PIP joint

 

2 Diagnosis top

Be careful to avoid overlap of other fingers in the x-rays. enlarge

Fixation options

Diagnosis is based on

  1. the clinical history of the trauma and mechanism of the injury
  2. the clinical examination of the patient
    1. palmar ecchimosis, swelling and pain in the area of detachment
    2. inability to flex the DIP joint. Make sure that flexion of the DIP joint is examined
  3. the x-rays

AP, lateral and oblique x-rays are necessary for diagnosis. Be careful to avoid overlap of other fingers in the x-rays.
Low-dosage radiographs, as used to visualize soft tissues, can be very useful to identify small flakes.


Always be sure to check for normal DIP joint flexion. enlarge

Examination

When the MP and PIP joints flex normally, sometimes the examiner might miss the fact that the DIP joint does not. Always be sure to check for normal DIP joint flexion.
Function of the flexor digitorum superficialis (FDS) can be checked by holding the non-injured fingers extended. The PIP joint should now flex normally, while the DIP joint is locked.


If flexion is not possible, the continuity of the FDP may be interrupted. enlarge

Function of the FDP is examined by holding the PIP joint of the injured finger in extension. The DIP joint should now be able to flex. If flexion is not possible, the continuity of the FDP may be interrupted.

3 Reduction top

Hyperextend the distal phalanx to gain maximal visualization of the joint (open book). enlarge

Visualize the joint

Hyperextend the distal phalanx to gain maximal visualization of the joint (open book).
Use a syringe to clear out blood clot with a jet of Ringer lactate.
Assess fracture geometry and look for comminution or impaction.
Often, comminution is not apparent from the x-rays, and can only be determined under direct vision.


If the tendon has retracted to the PIP joint, the zigzag incision has to be extended to the PIP joint. enlarge

Reposition the tendon

If the tendon has retracted to the PIP joint, the zigzag incision has to be extended to the PIP joint.
Use a small flexible catheter or similar tool to retract the tendon.
Use a 4 (o) suture to hold the end of the FDP in the Mansson fashion and pass these through a suture loop. The tendon will be repositioned by exerting pull with the suture.


Alternatively, the FDP can be sutured to the tube. By pulling it, the tendon will be repositioned. enlarge

Alternatively, the FDP can be sutured to the tube. By pulling it, the tendon will be repositioned.

4 Suture fixation top

If there is comminution present, the comminuted bony fragments have to be excised. enlarge

Comminution

If there is comminution present, the comminuted bony fragments have to be excised. This is also true if a flake is so small that it does not contribute to any form of reattachment..


Resect any comminuted fragments, or small flake. enlarge

Resect fragments

Resect any comminuted fragments, or small flake.


It is mandatory to use a drill guide to protect the soft tissues. enlarge

Drilling

Drill a 1.5 mm hole aimed obliquely from proximal to distal and palmar to dorsal, exiting through the nail, but avoiding the lunula (germinal matrix).
It is mandatory to use a drill guide to protect the soft tissues.


Both needles exit dorsally through the nail. enlarge

Insert sutures

Use 4.0 multifilament nonabsorbable sutures with double-mounted straight needles.
Interweave a suture through the detached distal end of the tendon and insert the two ends of the suture into the drill hole. Both needles exit dorsally through the nail.


Now gently approximate the tendon to the fracture surface by pulling the sutures in a dorsal direction. enlarge

Reduce tendon

Now gently approximate the tendon to the fracture surface by pulling the sutures in a dorsal direction.
Confirm the position under direct vision.


Tighten the suture over the nail, anchoring it around a piece of cotton, which also serves to protect the nail from excessive... enlarge

Tighten sutures

Tighten the suture over the nail, anchoring it around a piece of cotton, which also serves to protect the nail from excessive pressure.

5 Alternative fixation top

This option has the advantage of sparing the nail bed and nail from injury, and is a less time-consuming procedure. enlarge

Comminution

Alternatively to the described method, a suture anchor can be used.
This (more expensive) option has the advantage of sparing the nail bed and nail from injury, and is a less time-consuming procedure.

v2.0 2016-06.30