Is osteonecrosis of the lunate bone an underestimated feature of systemic sclerosis? A case series of nine patients and review of literature

Osteonecrosis of the lunate bone, also known as Kienböck's disease, is a very rare disease of unknown cause. Until today, only six cases of osteonecrosis of the lunate bone in patients with systemic sclerosis (SSc) have been reported in the literature. It is unknown whether these few cases reflect only a coincidence of two rare diseases or whether osteonecrosis of the lunate bone is a potential currently underestimated disease-associated feature of SSc. In this study, we report the clinical course of nine SSc patients with magnetic resonance imaging proven osteonecrosis of the lunate bone and discuss associated disease characteristics and potential underlying pathophysiological mechanisms. Overall, our observations suggest that osteonecrosis of the lunate bone is a frequent and so far under-recognized manifestation of SSc which might be linked to SSc-related vasculopathy. It is important to distinguish osteonecrosis of the lunate bone from wrist arthritis in SSc patients because the clinical treatment is different. In general, the clinical progression of osteonecrosis of the lunate bone seems to be slow in SSc patients. As most of the patients have only minor complaints, watchful waiting in combination with analgesic therapy seems to be a feasible treatment approach in most patients whether an operative intervention might be necessary in rapid progressive cases.