Kienbock's Disease

Definition 

 

Avascular necrosis & subsequent disintegration of lunate

 

Aetiology

 

50-75% history of trauma

 

Occasionally seen in sickle cell / steroid use

 

Pathogenesis

 

Vascular Theory

 

Trauma disrupting vascularity

- single incident with disruption of blood supply

- multiple compression fracture with loss of blood supply to fragments

 

Linschield 

- high incidence of coronal fractures seen on CT

- not apparent on AP film

- disrupts intra-osseous anastomoses

 

Lunate Vascularity (Gelberman)

 

Group 1

- 10% 

- single incomplete palmar blood vessel

- higher risk AVN

- severe hyperextension may disrupt it

 

Group 2

- 90% 

- dorsal & palmar blood vessel

- well vascularized 

- need intra & extraosseous disruption

- low risk AVN

 

AVN not seen in lunate dislocation

- flap of volar capsule usually remains attached

 

Mechanical Theory

 

Normal ulna plus

- +2 to -6 mm

- +2 SD mean

 

Ulna minus variance

- subjects lunate to greater compression & shear forces

- increased radioulnar forces

- seen in 75% Kienbock's

- only 25% normal population

 

Ulna Minus

 

Lichtmann Classification

 

Stage 1 

- no radiological change 

- diagnosed on bone scan / MRI

 

Stage 2 

- sclerosis

 

Kienbocks Disease Stage 2

 

Stage 3 

- collapse / fragmentation

 

A: Normal carpal height

B: Loss of carpal height / scaphoid flexed / capitate migrates proximally

 

Stage 4 

- degeneration

- pan carpal arthritis (radiocarpal / midcarpal)

 

Epidemiology

 

Occurs in young active adults 

- age 20-40 

- usually dominant hand 

- rarely bilateral

- men > women

 

History

 

Gradual onset of stiffness & pain 

50% history of trauma

 

Examination

 

Decreased ROM

Poor grip strength

Tender over lunate

Passive dorsiflexion middle finger gives pain

 

X-ray

 

Kienbock's

- progressive changes of AVN

- mottling / collapse / OA

- look for scaphoid flexion / capitate descent

 

Ulna Variance

 

Supination and pronation alter values

- need zero rotation view

 

90 / 90 view

- PA film with wrist in neutral

- elbow 90° / shoulder Abducted 90°

 

Line from lunate fossa and ulna head

- mean ulna variance is 1 mm (range 2 - 4)

 

Ulna Negative

 

Bone Scan / MRI

 

Demonstrate AVN

 

CT

 

Often show coronal fracture with palmar fragment extruded

- ? Cause of decreased palmar flexion

 

NHx

 

Usually one of progressive collapse

- cccasionally can arrest and even reverse

- these patients may not be seen

- the usual patient presents late 

- makes interpreting treatment options difficult

 

Non-operative Management

 

Splint 

 

Rarely effective

- Stage 1

- trial of immobilisation for 3/12 to aid revascularisation

 

1.  Stage II / IIIA Negative Ulna Variance

 

Radial Shortening ~ 2mm 

 

Theory

 

With negative variance often have thick healthy TFCC 

- can tolerate loading well

 

Radius normally takes 80% of load

- with ulnar minus is increased to 96%

 

Redistribute stresses 

- 2mm: 20% decrease radiolunate load

- 4mm: 40% decrease in radiolunate load

- less stress on lunate / revascularisation 

- relative lengthening of tendons may decrease compressive forces

 

Aim

- aimed for neutral or +1 mm ulnar variance

- if >1mm positive then risked ulnar abutment

 

Technique

- volar approach

- resection of desired amount

- can use cutting guides which give 2 parallel oblique osteotomies of set distance

- ensure not violating DRUJ

- application volar plate

- can be done dorsally but plate can become problem

 

Results

 

Quenzer J Hand Surg 1997

- 68 patients

- diminished pain 90%

- increased grip strength 75%

- increased ROM 50%

- 1/3 had signs lunate revascularisation

 

2.  Stage II / IIIA with Neutral or Positive Ulna Variance

 

Capitate Shortening + Capitohamate fusion

 

Aim

- unload the lunate

 

Result

 

Almquist Hand Lin 1993

- 83% revascularisation and healing

 

Vascularised Bone graft 

 

Indications

- best success in stage II / precollapse

- can combine with capitate shortening

 

Options

- 2nd dorsal intermetacarpal A & V

- distal radius pronator quadratus pedicle

- dorsal distal radius on pedicle

 

3.  Stage IIIB

 

Limited fusion

 

A.  STT 

 

Theory

- lunate collapsing 

- scaphoid takes more of load and goes into flexed position much like DISI

- STT fusion gives stable radial column for load bearing

- prevents radiocarpal degeneration

 

Technique

- dorsal approach 3/4

- take scaphoid out of flexion / extend

- K wire into position

- fuse to trapezium and trapezoid using bone graft from distal radius

 

B.  4 corner fusion 

 

Theory

- provides ulnar load bearing column

 

Problem

- lunate is poor quality / necrotic

 

Proximal Row Carpectomy

 

Always consider adding denervation

 

4.  Stage IV

 

PRC

- contraindicated with severe capitate degeneration

 

Arthrodesis

- manual worker