Kienbock’s Disease

Video

Definition

  • Avascular necrosis & subsequent disintegration of lunate
  • Described 1910 by Kienbock (Vienese radiologist)

Aetiology

  • Avascular necrosis of lunate
  • Probably result of trauma
  • Mechanical & vascular theories

Vascular Theory

  • Due to trauma disrupting vascularity
  • May be
    • Single incident with disruption of blood supply
    • Multiple compression fractures with loss of blood supply to fragments
  • Lunate vascularity (Gelberman dye studies)
    • 8% Single incomplete palmar feeder
      • Hence higher risk AVN
      • Severe hyperextension may disrupt it
    • 92% Dorsal & Palmar blood vessels
      • “X” “I” “Y” configuration
      • Well-vascularized
      • Need intra & extraosseous disruption
      • Low risk AVN

Mechanical Theory

  • Ulnar variance
    • Normal +3 to -6 mm (2 SD mean)
    • Ulnar minus variance
      • Subjects lunate to greater compression & shear forces
      • More common in Kienbock’s
      • Gelberman 1975
      • 75% with Kienbock’s cf. 25% in unaffected patients
      • Assess on standard XR
  • Realise that true Kienbock’s rarely seen as result of perilunate/ lunate dislocations (<1%)

Epidemiology

  • Occurs in young active adults
  • Age 20-40
  • Usually dominant hand
  • Rarely bilateral

Anatomy

Pathology

Classification

Lichtmann

  • Classified into 4 stages according to x-ray

Stage 1 normal

  • No radiographic changes
  • ? may be possible to see on MRI

Stage 2 sclerosis

  • Density changes
  • Sclerosis of proximal pole

Stage 3A fragmentation

  • May be evidence of compression fracture
  • Radiolucent or radiodense line

Stage 3B collapse

  • Collapse of lunate
  • Flattening

Stage 4 degeneration

  • Pancarpal arthritis
  • Operations aimed at promoting revascularisation for stages 1 & 2

History

  • Gradual onset of pain & stiffness in wrist
  • Usually no history of trauma (but seen in up to 50%)

Examination

  • Tenderness over lunate
  • Passive dorsiflexion MF pain
  • Diminished grip strength
  • In later stages ↓ ROM from Osteoarthritis

Investigations

Plain x-ray

  • Progressive changes of avascular necrosis
    • Mottling
    • Collapse
    • Degenerative arthritis
  • XR for Ulna Variance
    • AP film with wrist in neutral
    • Elbow flexed 90°
    • Shoulder abducted 90°

Bone scan

  • Increased uptake in early stages

MRI

  • Shows changes before bone scan becomes positive

Differential Diagnosis

Treatment

Nonoperative

  • No treatment is satisfactory way of managing Kienbock’s
    • Beckenbaugh 1980 70% no worse at 7 years
    • Kristensen 1986 77% minimal pain at 18 years
    • Saffar 1982 few changed work at 10-30 years

Splintage

  • ? Allows fractures to heal & revascularise
  • Rarely effective

Operative

Early – Stage 1, 2 & 3

  • Ulna Minus
    • Radial shortening
      • Rationale is to redistribute stresses
      • Decreased stress on lunate may allow it to revascularise
      • Try to achieve ulnar neutral wrist
      • ~ 2mm shortening
        • 2mm = 20% ↓ in radial load
      • Volar T Plate
      • Good-excellent results 80-90% success
      • Can consider combining with vascularized graft into lunate using metacarpal artery
    • Ulnar lengthening
      • Other form of joint levelling
      • Don’t do as high rates of nonunion
  • Neutral Ulna Variance
    • Radial closing wedge
    • Ulna opening wedge
    • Capitate-Hamate Fusion
    • Arthroscopic drilling (forage)

Late – Stage 4 (? 3 also)

  • Limited fusion
    • Scaphotrapeziotrapezoid (STT) fusion
    • Unloads lunate fossa & transfers load to scaphoid fossa
    • Unpredictable
  • Silicone replacement
    • Poor long-term results
    • No longer advocated
  • Proximal row carpectomy
    • ? Best procedure for late cases
  • Can consider Buck-Gramko denervation if pain is main symptom

Operative Salvage Procedures

  • Arthrodesis of wrist
    • Manual laborers
  • Proximal Row Carpectomy
    • Good if Low Demand
  • Lunate Excision
    • Controversial
    • Good results in 1 study (Kawai)

Management Approach

  • Literature not proven to show operative approach better than observation alone
  • Therefore observation is reasonable option for all stages of Kienbocks
  • Stage 1
    • Observe
  • Stage 2
    • Observe
    • Arthroscopic drilling (forage)
    • Radial osteotomy ± vascularised bone graft
  • Stage 3
    • Observe
    • Radial osteotomy ± VBG
    • If carpal collapse then scapholunate capsulorraphy
  • Stage 4
    • Observe
    • Radial osteotomy
    • Denervation
    • Total fusion

Complications

Prognosis

  • STT fusion or Radial Shortening doesn’t prevent collapse

References