KIENBOCK'S DISEASE

Question 1

Risk factors for Kienbock’s disease

Answer 1

3 main groups
1. Vascular factors
- highest risk with I-pattern of intraosseous blood supply
- seen in 30% Kienbock's patients
2. Structural/ Biomechanical factors 
- negative ulna variance
- decreased radial inclination
- lunate geometry/ shape
These factors increase radiolunate loading
3. General factors
- steroids
- EtOH
- repetitive trauma

Question 2

Blood supply to lunate

Answer 2

Extraosseous and intraosseous
Extraosseous = dorsal and volar vessels
- volar more reliable/ predictable
- dorsal absent in 10%
Intraosseous = 3 main patterns
- X pattern
- Y pattern = 2 vessels anastomose into 1
- I pattern = single vessel, no anastomosis
I pattern has highest AVN risk = 30% Kienbock’s patients

Question 3

2 main investigations for diagnosis of Kienbock’s

Answer 3

1. Plain radiographs
2. MRI = look for uniform changes
   - MRI is useful for diagnosis in early disease when xrays are normal
   - MRI is useful for management in late disease to assess articular cartilage of capitate and lunate fossa

Question 4

Differentials with non-uniform changes in lunate on MRI

Answer 4

1. Trauma
   - fracture
   - ulnocarpal abutment
2. Tumour
   - enchondroma
   - osteoid osteoma

Question 5

3 main factors that affect loading through lunate

Answer 5

1. Coverage of lunate by radius = main factor
2. Ulna variance = negative ulna variance increases loading through radiolunate articulation
3. Scaphoid position = scaphoid flexion increases loading through radiolunate articulation

Question 6

Measurement of carpal height ratio

Answer 6

Measured on PA view
Carpal height = distance between distal articular surface of radius and distal articular surface of capitate
Carpal height ratio = ratio of carpal height to 3rd MC length
Normal = 0.54

Question 7

3 conditions that decrease carpal height ratio

Answer 7

1. Kienbock’s disease
2. Carpal instability
3. Carpal arthritis = SLAC/ SNAC

Question 8

Classification of Kienbock’s disease

Answer 8

Lichtman classification = radiographic classification with 4 stages
Stage I = normal xray
- pain due to synovitis
- MRI abnormal with uniform low signal in lunate
Stage II = lunate sclerosis but shape preserved
Stage III = lunate fragmentation and collapse
IIIA = carpal height preserved
IIIB = proximal migration of capitate, scaphoid flexion
Stage IV = pancarpal arthritis
Stages I, II and IIIA are pre-collapse
Stages IIIB and IV are collapse

Question 9

5 main radiographic features on PA view

Answer 9

1. Lunate appearance = normal, sclerosis, fragmentation, collapse, arthritis
2. Ulna variance
3. Radial inclination
4. Carpal height ratio = Capitate proximal migration
5. Scaphoid flexion = signet/ cortical ring sign

Question 10

Surgical goals in Kienbock’s disease

Answer 10

1. Restoration of favourable biomechanical environment

2. Revascularisation = indirect vs. direct

Question 11

5 main surgical options in Kienbock’s disease

Answer 11

1. Joint levelling procedures
   - radial shortening osteotomy
   - ulna lengthening osteotomy
   - radial wedge osteotomy = to increase inclination
2. Revascularisation procedures
   - vascular bone graft = bone block with its pedicle
   - ICBG and insertion of vascular pedicle into lunate
   4 pedicle options:
   - 1-2 ICSRA
   - PQ artery
   - 1st, 2nd or 3rd dorsal IMA
   - 4-5 ECA
   - Often combined with temporary ex-fix or SC pinning to unload lunate
3. Limited/ partial wrist fusions = to maintain height
   - CH fusion
   - SC fusion
   - STT fusion
4. PRC
5. Complete wrist fusion

Question 12

Management of pre-collapse (Stage I-IIIA) Kienbock’s

Answer 12

Non-operative (NSAIDs, splinting) has low success = natural history is progression
Operative = depends on ulna variance
1. Joint levelling if negative ulna variance/ decreased radial inclination
2. Capitate shortening osteotomy and capitohamate fusion if neutral/ positive UV = to unload CL articulation
+/- Revascularisation and temporary ex-fix

Question 13

Almquist procedure

Answer 13

Capitate shortening osteotomy and capitohamate fusion

• unloads radiolunate articulation by 60%
• increases radioscaphoid loading by 25%

Question 14

Management of collapsed (Stage IIIB-IV) Kienbock’s

Answer 14

1. Lunate excision and limited/ partial wrist fusions
   - Capitate lengthening osteotomy or PL tendon graft = to fill lunate void
   - Scaphocapitate fusion = unloads RL articulation by 10%
   - STT fusion = unloads RL articulation by 5%
2. PRC = requires capitate and lunate fossa to be intact
3. Complete wrist fusion