Distal Phalanx Injuries

Fractures of the Distal Phalanx

Fractures of the distal phalanx are common (usually crush injuries)
Kaplan classification: longitudinal, transverse, comminuted
These are not innocuous – patients may be symptomatic for months!

– In general, these injuries DO NOT require operative intervention.
– Immobilization in hairpin/lateral splint x 3 to 4 weeks is good for comfort.
– Immobilization is for PAIN only; these do not require immobilization for stability and maintenance of reduction.

Nail Bed Injuries

Evacuate the subungual hematoma with a hot paper clip
Meticulous repair of the nail bed is the best means of minimizing late nail deformity after open crush injury where the nail plate has been avulsed off and the nail bed laceration is exposed.
In closed nail bed injuries, with an intact nail plate, just drain the subungual hematoma.

Mallet Finger of Tendon Origin

These can occur by 1. Stretching of the tendon. 2. Tendon rupture. 3. Avulsion fracture (when small, should be managed as a pure tendon injury).
The results of treatment of mallet fingers are not universally good, by any methods.
Treatment should depend on time elapsed after injury, previous treatment, degree of extension loss, degree of functional disability, and age.

Acute injury (less than 4 weeks): Immobilization in Stack splint x 6-10 weeks – splint only the DIP in as much hyperextension as possible. Ultimately, some lag is inevitable.
Chronic injury: many of these will benefit from Stack splint. Numerous surgeries have been proposed. Many will have no problems at all. The patients most likely to be symptomatic are those who develop a swan-neck deformity, with a supple hyperextension posture of the PIP joint that accentuates the DIP extensor lag. These may benefit from a Fowler central slip release.

Mallet Finger of Bony Origin (Mallet Fracture)

Operative treatment offers no advantage over splinting of the DIP for 6-8 weeks
Virtually all mallet fractures should be treated with Stack splinting of the DIP joint
Perhaps the only indication for fixing these is for the mallet fracture with SIGNIFICANT volar subluxation, though you wonder if these would do just as well if you reduced them and splinted them. Significant remodelling of the joint surface can be expected in nonoperative management.

FDP Avulsion (Jersey Finger)

Caused by forceful hyperextension of the DIP joint with the FDP in maximal contraction.
The diagnosis is made by demonstrating full DIP flexion – it is often missed because this detail in the physical examination is neglected.
In most cases, the tendon ruptures from bone; it can avulse a little flex of bone too.
Classified according to where the tendon ruptures to (Leddy/Packer):
I. retraction into the palm, severing all blood supply. Fix within 7-10 days, or you’ll never get it back.
II. retraction to the chiasma of the FDS, sometimes with a flex of bone. Fix early, but these can be fixed up to 3 months later.
III. retraction to the A4 pulley with a large chunk of bone.

As a general rule, get on and fix these as soon as possible (within a week).
Reattachment is best done with pull-out technique.
If seen late, they may have PIP stiffness secondary to a rolled up stump at that level; physio to regain full, painless PIP motion. If no resolution, excise the FDP stump. For late injuries, consider DIP fusion, free tendon graft, excision of FDP stump, or benign neglect.

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