Kienböck Disease

Kienböck disease, also known as lunatomalacia, is an idiopathic necrosis of the lunate. It has been suggested that chronic microfractures lead to vascular compromise and subsequent osteonecrosis. Chronic microfractures may occur due to external factors (e.g., work-related), or anatomic variations (see below).

The variable blood supply has been also suggested as a predisposing factor. The blood supply of the lunate is through proximal carpal arcades, usually along its palmar and dorsal surfaces, but up to 1/4 of lunates may have a single supply (either dorsal or palmar).

Mechanical anatomic factors that have been suggested to predispose patients include:

• Smaller lunate
• Flatter radial inclination : Angle between a line from the ulnar side of the carpal surface of the radius to the tip of the radial styloid and a line perpendicular to the axis of the ulna.
• More radial tilt of the lunate.
• Negative ulnar variance: Disputed by more recent work.
• High uncovering index of the lunate: Length of the proximal surface of the lunate that does not articulate with the radius divided by the total proximal surface of the lunate. Disputed by more recent work.
• A trapezoidal shape of the lunate
• The presence of a medial lunate facet articulating with the hamate

The patient here had was on chronic steroid therapy and started having wrist pain after an episode of wrist trauma a while back.

References

• Ledoux P, Lamblin D, Wuilbaut A, Schuind F. A finite-element analysis of Kienbock's disease. J Hand Surg Eur Vol. 2008 Jun;33(3):286-91.
• Schuind F, Eslami S, Ledoux P. Kienbock's disease. J Bone Joint Surg Br. 2008 Feb;90(2):133-9.
• Thienpont E, Mulier T, Rega F, De Smet L. Radiographic analysis of anatomical risk factors for Kienböck's disease. Acta Orthop Belg. 2004 Oct;70(5):406-9.