Teaching Case

A 34 years old male driller by profession presented to our radiology department with pain in
right wrist .Pain had worsened over a period of six months and patient was having difficulty in doing daily works

X ray of right hand revealed significant sclerosis of lunate bone with disuse osteopenia in adjacent carpal bones. MR images through the right wrist showed collapse of the lunate with diffuse abnormal T1 hypointense signals seen in it. Abnormal signals were also seen involving the capitate and scaphoid bone (proximal to the waist of scaphoid). Few abnormal signals with focal areas of cartilaginous thinning and tiny cysts were identified involving the articular and sub articular surfaces of all the carpal bones, distal radius and the ulna. Overall findings were consistent with osteonecrosis of the lunate bone.

Kienböck’s disease also referred to as osteonecrosis of lunate bone or called lunatomalacia or avascular necrosis of the lunate bone, is a rare condition in which lunate bone, loses its blood supply leading to avascular necrosis. [1] Its causes are multifactorial, commonly affecting men between the ages of 20 and 40 years. Negative ulnar variance results in increased shear stress to the lunate bone which might be a risk factor to develop lunate necrosis through still unknown mechanisms. Regarding lunate pressure it has been debated that increased intraosseous pressure caused by venous stasis (i.e. in extension) might be another risk factor or cause for lunate necrosis. [2].
CLINICAL PERSPECTIVE: In early stages of the disease patient may present with pain, edema and limited wrist motion. With disease progression bone destruction and collapse occurs resulting in secondary wrist osteoarthritis. Early diagnosis and treatment help in prevention and progression of necrotic changes and bone collapse.

IMAGING PERSPECTIVE: The management of Kienböck’s disease is highly dependent on the stage of the disease based on the Lichtman classification system. MRI (Magnetic resonance imaging) is helpful early in the disease when plain radiographs are not helpful however bone contusion or acute fracture must be ruled out by adequate clinical history for the differential of a Kienböck's disease stage I. Contrast-enhanced MRI is important for assessment of the degree of necrotic tissue and for the treatment of stage II and III A disease. MRI with contrast is often not necessary in stages I, III B, III C, or IV because in such cases degree of necrosis does not usually change treatment. [3]

OUTCOME: There is lack of consensus among hand surgeons about treatment of disease. For patients with ulnar-minus variance and stage I disease immobilization is recommended. For stages II or III A disease with ulnar-minus variance, an equalization procedure is attempted. In stage III B disease, Scapho-trapezial-trapezoidal (STT) arthrodesis is done to restore carpal stability and prevent further degeneration. In stage IV disease, proximal row carpectomy (PRC) or wrist arthrodesis is done. [4] Take home message is that radiology plays an important role in the diagnosis and classification of the disease process. MRI plays a vital role in the early diagnosis of stage I of the disease process and is superior in sensitivity and specificity to bone scan in early detection and prevention of disease progression.

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