Kienböck

Kienböck disease, or avascular necrosis of the lunate, is a condition in which the blood supply to the lunate bone of the wrist is disrupted, leading to bone death and potential collapse. The eponym honors Austrian radiologist Robert Kienböck, who described the condition in the early 20th century. The lunate sits centrally in the proximal carpal row and plays a key role in wrist motion; disruption of its vascular supply can cause pain, stiffness, and, over time, arthritis.

Most cases are idiopathic, but risk factors include negative ulnar variance (where the ulna is shorter than the radius, increasing load on the lunate), repetitive trauma, and other conditions that predispose to avascular necrosis. The condition typically presents with insidious wrist pain and limited range of motion, often without a prior acute injury. Physical examination may reveal tenderness over the lunate and reduced grip strength.

Diagnosis starts with plain radiographs, but early disease can be radiographically silent. MRI or CT is used to detect necrosis and assess stage. The Lichtman classification (stages I–V) describes progression from a normal radiograph (stage I) to lunate collapse with carpal arthritis (stage IV–V).

Treatment depends on stage. Early, nonoperative management may include immobilization and activity modification, along with addressing risk factors. Surgical options range from revascularization procedures and unloading osteotomies to partial or total wrist arthrodesis or proximal row carpectomy in established arthritis. The prognosis varies with stage at diagnosis; early treatment improves function, while advanced disease may require salvage procedures.