Mallet finger- symptoms, diagnosis & Treatment

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