Kienbock's disease

Kienbock's disease is avascular necrosis of the lunate — the central bone of the wrist loses its blood supply, progressively collapsing and fragmenting. The cause is not fully understood; a combination of traumatic disruption, anatomic variation (negative ulnar variance), and vascular anatomy likely contributes. It most often affects dominant-hand-dominant young men in their 20s–40s.

Early stages present as dorsal wrist pain and reduced grip with few X-ray findings; late stages show lunate collapse with secondary wrist arthritis.

Plain X-rays are normal in stage I. MRI is the most sensitive early test, showing low T1 signal throughout the lunate. CT defines lunate fragmentation. Staging follows the Lichtman classification (I–IV), which guides treatment.

Most stages beyond I benefit from surgical intervention to halt progression.

External patient-education references and related OSI pages for additional background:

• Britannica — Hand (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language