kienbock’s disease

definition

· syn. lunate malacia

· Kienbock 1910

· avascular necrosis and subsequent disintegration of lunate

epidemiology

· occurs in young active adults

· age 20-40

· usually dominant hand

· rarely bilateral

aetiology

Avascular necrosis of lunate

· probably result of trauma

· may be

· single incident with disruption of blood supply

· multiple compression fractures with loss of blood supply to fragments

Ulnar minus variance

· more common (75% cf. 25% in unaffected patients)

· subjects lunate to greater compression and shear forces

clinical

Symptoms

· gradual onset of pain and stiffness in wrist

· usually no history of trauma

Signs

· tenderness over lunate

· diminished grip strength

· in later stages decreased ROM

radiology

Plain x-ray

· progressive changes of avascular necrosis

· mottling

· collapse

· degenerative arthritis

Bone scan

· increased uptake in early stages

MRI

· shows changes before bone scan becomes positive

classification

Lichtmann

· classified into 4 stages according to x-ray (Lichtmann)

Stage 1 - sclerosis

· density changes

· sclerosis of proximal pole

Stage 2 - fragmentation

· may be evidence of compression fracture

· radiolucent or radiodense line

Stage 3- collapse

· collapse of lunate

· flattening

Stage 4 - degeneration

· pancarpal arthritis

treatment

Nonoperative

· in form of splintage

· allows fractures to heal and revascularise

· rarely effective

Operative

Early

· radial shortening

· rationale is to redistribute stresses

· decreased stress on lunate may allow it to revascularise

· good results (80-90% success)

Late

· limited fusion

· scaphotrapeziotrapezoid fusion

· unloads lunate fossa and transfers load to scaphoid fossa

· silicone replacement

· poor long-term results

· no longer advocated

· salvage procedures

· arthrodesis of wrist

· proximal row carpectomy