Diagnosis: Stage IId Kienbock’s disease
Discussion: Kienbock’s disease is the condition of avascular necrosis of the lunate. Onset is typically insidious, with patients presenting with dorsally located central wrist pain. The peak age of onset is 20 to 40 years of age, with males affected twice as often as females. Bilateral disease is uncommon but does occur.
Predisposing factors to the development of Kienbock’s disease include: negative ulnar variance, oblong or square lunate geometry, tenuous lunate vascularity, and TFC complex compliance. The mechanism is thought to be acute trauma or repetitive microtrauma with interruption of the intra-osseous blood supply to the lunate.
There are several classification systems. The most clinically relevant is the Lichtman classification, which divides the disease into four stages based on the plain radiographic findings.
In stage I disease, the plain radiographs are normal. Stage II disease is typified by density change of the lunate, now sclerotic, without evidence of carpal instability. Subtle collapse of the radial articular surface may or may not be present.
Stage III is characterized by lunate collapse and is subdivided based on the absence (stage IIIa) or presence (stage IIIb) of fixed rotary subluxation of the scaphoid. Dynamic rotary subluxation may be present in stage IIIa disease. Generalized arthrosis of the carpus heralds the development of stage IV disease.
Lichtman’s classification can be adapted to MRI as follows:
Stage I
- Marrow hyperintensity on water-weighted sequences (T1 sequences may be initially normal)
- Intermediate signal surrounding synovitis
- Presence or absence of microtrabecular fractures and transverse fracture
Stage II disease is usually divided into four subclasses:*
- Stage IIa - Focal central hypointensity on T1 with increased signal on T2
- Stage IIb - Focal central hypointensity on T1 and T2
- Stage IIc - Generalized hypointensity on T1 with increased signal on T2
- Stage IId - Generalized hypointensity on both T1 and T2
* Lunate height is typically preserved in Stage II disease. However, late Stage II disease can have early radial-sided height loss.
Stage III disease can be divided into two subclasses:
Stage IIIa is characterized by:
- Distal to proximal lunate collapse with anterior-posterior elongation
- Proximal migration of the capitate
Stage IIIb is characterized by:
- The above, plus rotary subluxation of the scaphoid
- Presence or absence of ulnar subluxation of the triquetrum
Stage IV is characterized by:
- Degenerative arthrosis of the lunate and carpus.
Treatment for Kienbock’s disease is hotly debated and not well-established. In general:
- Stage I disease is treated conservatively, with immobilization and nonsteroid anti-inflammatory drugs (NSAIDs). If there is no improvement, surgical intervention is considered.
- Stage II disease is treated with a lunate revascularization procedure and an “unloading” procedure of the lunate, typically either radial or capitate shortening or ulnar elongation. Triscaphe fusion has also shown to be effective.
- Stage IIIa disease is treated with reconstruction of the lunate and an unloading procedure.
- In Stage IIIb disease, the scaphoid rotation must also be addressed.
Stage IV disease requires an advanced salvage-type procedure.
