Kienbock’s Disease

Epidemiology

  • Male > Female (2:1)
  • 20-40 year olds
  • Dominant hand

Aetiology

  • Unknown but likely multifactorial
  • Mix of anatomical and mechanical factors leading to a susceptible lunate:

  1. Ulna –ve variance = increased shear forces across lunate

    • Seen in 75% of Kienbock’s cases
    • Normal wrist loading: 80% radius, 20% ulna
    • With -ve ulna variance: 95% radius, 5% ulna

  2. 20% of lunates have a single nutrient artery

  3. Traumatic past event that alters blood supply

  4. Repetitive microtrauma

Natural History

  • Ischaemia → Necrosis → Sclerosis → Structural failure (Collapse) → Wrist instability → Secondary arthritis

Investigation

X-Ray

  • Only positive in later stages
  • Assessing ulna variance
    • Done on a PA view with neutral rotation
    • Shoulder & Elbow at 90 degrees
    • Ulna fossa to radius – normal = 1mm (range 2-4mm)
  • Evaluating extent of degenerative disease
  • Good for quantifying degree of carpal height/collapse
    • Carpal height ratio <0.5 is abnormal

MRI

  • Most sensitive and specific – shows features of AVN isolated to lunate
    • Low signal on T1 and T2 diffusely throughout lunate
    • Initially mixed signal may be present

Bone Scan

  • Replaced by MRI

CT

  • No additional info compared to plain XR

Classification - Lichtmann

Stage 1

  • No XR features
  • MRI shows altered signal

Stage 2

  • Sclerotic Lunate but normal shape

Stage 3

  • Lunate collapse and fragmentation (decreased carpal height ratio)
    • 3A: No instability – scaphoid not in fixed rotation
    • 3B: Instability – scaphoid rotated and fixed

Stage 4

  • Pancarpal arthritis

Source: Lieberman J (2009), AAOS Comprehensive Review, American Academy of Orthopaedic Surgeons

Presentation

  • May be asymptomatic incidental finding or triggered by new trauma
  • Young adult
  • Non-specific pain, decreased ROM, grip strength

Management Principles

  • Goals depend on stage of disease and symptoms

Stage 1

  • Splint, NSAIDs, activity modification, and monitor
  • May or may not work

Stage 2 to Stage 3A

  • Aim: Prevent carpal collapse and instability
  • Core decompression of radius
    • Stimulates increased blood flow to lunate
    • Does not alter loading or prevent collapse

If patient has negative ulna variance

  • Joint Levelling Procedures
    • Radial shortening, ulna lengthening
  • Radial Shortening Osteotomy
    • 4mm shortening decreases radio-lunate load 40%
    • Aim for neutral or 1mm +ve variance

If patient has neutral or positive ulna variance

  • Consider radial core decompression if Stage 2
  • Capitate Shortening or Capito-Hamate Fusion
    • Better for Stage 3A
    • Unloads lunate
  • STT Fusion or 4 Corner Fusion are also options

Vascularised Bone Grafting of Lunate

  • Used successfully in Grade 2-3A
  • Best results in Grade 2 – pre-collapse
    • Controversial in Grade 3A
  • 4-5 intercompartmental supraretinacular artery is preferred

Stage 3B

  • Prevent onset of pancarpal arthritis
  • Limited fusion

STT Fusion

  • Corrects DISI and allows loading through scaphoid
  • Offloads lunate and limits development of arthritis

4 Corner Fusion

  • Offloads carpus but includes diseased lunate in fusion

PRC and Wrist Fusion

  • Also reasonable options

Stage 4

  • Salvage Procedures

PRC (Proximal Row Carpectomy)

  • Better for older, lower-demand patients
  • Not possible if capitate arthritic or collapsed
    • Arthritis will persist after PRC

Total Wrist Fusion

  • Better for young, heavy wrist users
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