Mallet finger- symptoms, diagnosis & Treatment

Mallet finger
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Mallet finger

  • Mallet finger is a loss of full, active extension of the distal interphalangeal (DIP) joint, resulting in unopposed flexor digitorum longus action to pull the distal phalanx into flexion.
  • Loss of extension can be due to avulsion of the tendon with or without a fragment of bone, or rupture or laceration of the tendon inserting on the distal phalanx.
  • Traumatic (except for rheumatoid arthritis)
  • Patient often presents late, weeks after the injury.
  • Radiographs are necessary to determine if an intra-articular fracture is present.

History

Most commonly closed/blunt injury

Can be open

Symptoms

➣ Mild swelling

➣ Little to no pain

➣ Extension loss at distal interphalangeal joint (DIPJ)

➣ Lag usually immediate; can be delayed

Mechanism

➣ Forced finger flexion against active extension

➣ Usually blunt impact injury to finger tip

➣ Terminal tendon avulsed

➣ Fractured from insertion

➣ Crushing injury: shoe cleat stepping on finger tip

➣ May occur “spontaneously”

  • Little or no significant trauma
  • May develop on delayed basis

➣ Ring/small finger most commonly affected

Common in soft ball, basketball, football, volleyball

Physical Exam

Swelling at DIPJ dorsally

Tenderness to palpation, dorsal DIPJ

Usually mild; may have no pain at all

Loss of active extension at DIPJ

Passive extension intact

Late findings

➣ Flexion contracture at DIPJ

➣ Hyperextension deformity at proximal interphalangeal joint (PIPJ; swan-neckdeformity)

Studies

Radiographs

➣ AP, lateral, oblique of hand/finger

➣ Usually normal appearance

➣ 25% have dorsal fracture avulsion

➣ Note percentage of articular surface involvement

➣ Note any volar joint subluxation

Differential Diagnosis

DIPJ dislocation

➣ Instability, tenderness at joint

➣ Radiographs show articular in congruity

Phalangeal fracture

➣ Tender at fracture

➣ Radiographs show fracture on lateral

DIPJ contracture

➣ Passive extension not possible

➣ Usually secondary findings at joint, arthropathy

Treatment

Mallet finger classification

Type I

  • Closed/blunt injury of terminal tendon
  • With/without small avulsion fracture

Type II

  • Open injury/laceration of terminal tendon

Type III

  • Deep abrasion with loss of soft tissue and tendon

Type IV

  • A: trans epiphyseal fracture, child
  • B: hyper flexion injury,20–50% dorsal articular fracture
  • C: hyper extension injury, >50% fracture,volar subluxation

Acute

➣ Establish type of injury

➣ Immediately treat based on injury type

Type I

➣ Place and maintain DIPJ in full extension

➣ Avoid blocking PIPJ flexion

➣ Avoid hyperextension

➣ Disregard small fracture fragments (<20%  articular surface), even if displaced

➣ Orthoplast volar gutter DIPJ splint (author’s preference)

  • Fabricated by occupational therapist
  • Custom- molded, perfect fit
  • Held with Velcro straps

Stack splint

  •  Various sizes available “off the shelf”
  • May not fit many well, too loose /too tight

Alumafoam splint

  •  Place volar, avoid dorsal
  • Held with tape/coban wrap
  • Skin does not tolerate well
  • Foam padding wears out quickly
  • Detailed instructions necessary

➣ Splint is worn at all times including showers/ baths.

➣ Remove splint 2–3 times per day to clean/ dry finger.

➣ Remove only while supporting DIPJ in full extension.

➣ Place finger flat on table, then remove splint.

➣ Never allow finger to be without supportin extension.

➣ Wear splint full-time 8 weeks.

➣ If at 8 weeks extension lag <15◦, wean splint.

Day: 2 hours on/ 2 hours off, night :all night

➣ Reassess after 2 weeks of weaning.

➣ If extension lag persist, wear 2 mor weeks.

➣ Reassess again.

➣ Therapy for flexion ROM usually not needed

  • If at 3 months there is loss of flexion, begin passive ROM.

Operative option: trans articular K-wire

  • Reserved for those who cannot wear splint
  • Dentist, surgeon, patient’s choice
  • Local digital block
  • 0.035 or 0.045 K-wire
  • Place oblique/ ongitudinal across DIPJ
  • Fewer complications if oblique
  • Remove pin after 8weeks and treat as above

Type II

➣ Open and repair with suture 5-0/6-0 mono filament

➣ Post operatively treat as typeI

Type III

➣ Soft tissue flap/reconstruction

➣ Tendon graft, if necessary

➣ Post operatively treat as type I

Type IV

➣ ORIF large articular fragments (>20 % articular surface)

➣ K-wires, min fragment screws

➣ Post operatively treat as type I

Late

➣ Treat like acute injury upto 6 months in some cases.

➣ Deformity has little or no functional impact; primarily cosmetic.

➣ If deformity mild/no functional problem, donothing

➣ Note any secondary hyperextension of PIPJ

  • Usually predisposed with volar plate laxity

➣ If deformity severe/secondary hyperextension of PIPJ

  • Spiral oblique retinacular ligament reconstruction
  • DIPJ fusion

➣ Silver ring blocking splint if surgery not wanted

Prognosis

Early splint treatment

➣ 80% good/ excellent result

➣ Good results decrease with lag in initial splint treatment

Return to play

  • Immediately with splint
  • 8–10 weeks without splint

Complications

  • Residual DIPJ extensor lag/ droop
  • May lose some DIPJ flexion

Trans articular wire

Similar result, greater morbidity

➣ Return to play immediately

Complications

  • Infection
  • Pain at previous pin site

Late repair/ reconstruction

➣ Fair/ poor result

➣ Return to play 6–8 weeks

➣ Complications

  • Residual deformity
  • DIPJ/ PIPJ stiffness

FusionDIPJ

➣ Goodresult

➣ Return to play immediately with splint

Complications

  • Loss of DIPJ motion
  • Diminished grip strength
  • Non union

Caveats and Pearls

Detailed instruction regarding splint use necessary

Splint cannot be removed without support

If pinning of joint preferred, place wire obliquely

➣ Less pin tract pain later

➣ If pin breaks, easily retrievable

Allow adequate time to heal; do not rush for ROM – 8 weeks minimum


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