Diagnosis and staging

Kienbock's disease affects patients of all ages and either gender. There need not be a history of antecedent trauma or previous wrist problems.

Symptoms tend to reflect the severity of the disease, ranging from mild discomfort to debilitating pain; however, this is not always the case, because some patients who have radiographic evidence of severe arthrosis remain relatively asymptomatic. Swelling and synovitis is commonly found about the lunate, both on the dorsal as well as the volar side. Wrist range of motion is often reduced, as is grip strength.

In 1977, Lichtman [6] proposed a staging system that described the clinical and radiologic classification for Kienbock's disease (Table 1). This system is now routinely used to stage the disease, guide treatment, and compare outcomes. There have been subsequent modifications to allow for the use of newer technologies, including MRI.

In Stage I, patients present with nonspecific pain suggestive of a wrist sprain or synovitis. Plain radiographs are either normal or demonstrate only a linear fracture of the lunate, with no sclerosis or collapse. MRI is ideal for this early stage, because the uniformly decreased signal intensity of both T1- and T2-weighted images in comparison with the neighboring bones reflects the loss of vascularity. Other causes of T1 signal loss must be considered in the differential diagnosis, including ulnar abutment, lunate fracture, and tumor. Furthermore, increased T2 signal intensity may represent revascularization. This finding is especially valuable in assessing lunate healing during and after treatment.

Lunate sclerosis is the hallmark of Stage II. One or more fracture lines may be present. Significantly, there is no loss of lunate height or other carpal involvement. Patients often present with chronic synovitis.

Table 1

Lichtman's classification of Kienbock's disease

Stage I Normal radiographs or linear fracture. On MRI, lunate shows low signal on T1-weighted images, and low or high intensity on T2-weighted images.

Stage II Lunate sclerosis on radiographs.

Fracture lines may be present.

Stage IIIa Lunate collapse, with normal carpal alignment and height

Stage IIIb Lunate collapse, with decreased carpal height, proximal migration of capitate, and fixed scaphoid flexion (ring sign)

Stage IV Lunate collapse with peri-lunate degenerative changes

In Stage III, the lunate collapses. This stage is further divided into two categories. In Stage IIIa, carpal height is maintained. Stage IIIb is characterized by proximal migration of the capitate. Also, fixed hyperflexion of the scaphoid leads to the ''ring sign.'' Stage IV heralds the onset of radiocarpal or midcarpal arthritis. These patients typically describe progressive wrist stiffness and symptoms consistent with their degenerative changes.

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