Unilateral developments of osteoarthritis and Charcot's joint in a patient with neurofibromatosis

Precise mechanism of developing neuropathic arthropathy known as Charcot's joint is not fully understood.A 55-year-old Japanese woman with neurofibromatosis-1 complained of right gonalgia in December 2001. Physical examination revealed a huge tumor in the right lower leg without signs of inflammation. Laboratory findings were unremarkable. Radiographic examination disclosed the presence of osteoarthropathy in the right knee joint. In contrast, radiologic findings of the right foot and ankle were compatible with neuropathic arthropathy. Further investigations could not reveal abnormal findings in the nervous system. To improve patient's quality of life, partial resection of the tumor was performed. The resected tissues were compatible with neurofibromatosis without malignant transformation. The patient newly noticed pains in the right ankle and tarsal joints one year after the operation. Restricted mobility and insufficient blood supply in the right knee arising from the huge tumor might accelerate development of osteoarthropathy through malnutrition of the chondrocytes. Because the patient did not experience the arthralgia before the operation, the tumor might damage the peripheral nerves unabling to receive afferent signals from such joints resulting in neuropathic arthropathy.The damaged peripheral nerves might be contributory to developing or accelerating neuropathic arthropathy.