Case history

A 40-year-old man presented with a history of continuous pain in his back for one year and knee and elbow joints for nine months. It was associated with early morning stiffness lasting for 15 min. He had also begun to have difficulty walking. He was a driver by profession and revealed that he had difficulty in getting out of the driver’s seat after driving for long periods. There was no history of redness in his eyes, he had no skin manifestations and his bowel and bladder were normal.

Musculoskeletal examination revealed painful spinal movements, mild tenderness present at the sacro-iliac joint and Schober’s test was positive. His right knee was tender and swollen with a restricted range of movement. The left knee was flexed (15?) and crepitus was present. His left elbow was tender and swollen with a mildly restricted range of motion. On the basis of the history and findings a provisional diagnosis of seronegative spondyloarthropathy with peripheral joint involvement was made. The rest of the examination, including general, dental and systemic, was normal.

On investigation the patient’s haemogram, blood biochemistry and erythrocyte sedimentation rate were normal. Antinuclear antibodies, C-reactive protein, riboflavin and human leukocyte antigen (HLA)-B27 were negative. S. calcium, magnesium, riboflavin, phosphorus and alkaline phosphatase levels were normal. An X-ray of the sacro-iliac joint revealed blurring of the sacro-iliac joint and X-rays of the forearm and wrist (Figure 1) and the leg (Figure 2) revealed interroseus membrane calcification. Magnetic resonance imaging (MRI) of the sacro-iliac was normal. An MRI of the spine revealed a hypo intense T1
gated image which was suggestive of metabolic disease.

On further probing it was found that the patient had consumed ground water and had drunk excessive amounts of black tea and that others in the neighbourhood had similar complaints. Fluoride levels of the consumed water were found to be 35 times the permissible limit. On the basis of the findings and the X-rays, a diagnosis of fluorosis was made.

He was given symptomatic treatment and an intra-articular injection of 80 mg depomedrol in the left knee. He was advised to decrease his intake of black tea and to consume only safe drinking water.

Discussion

Skeletal fluorosis is associated with prolonged accumulation of fluoride in the body. It results in fragile bones with low tensile strength and is also known to affect the joints and bones.

The early stages of the disease may essentially be asymptomatic or present as subtle changes such as pain in the neck or back with rigidity, joint pains in multiple joints and paraesthesias in the limbs.1 This can easily be mistaken for other conditions such as rheumatoid arthritis, osteoarthritis or seronegative spondyloarthropathy.2 Fluorosis is however known to be more prominent in the axial skeleton than the peripheral.

Joint effusion in patients with skeletal fluorosis has not been reported. However, Savas et al. showed evidence of increased severity of knee osteoarthritis in patients suffering from skeletal fluorosis, which may be the possible explanation in our case.