Limited knee joint range of motion due to invisible gouty tophi

OBJECTIVES: Tophi deposits are a well-known cause of joint destruction, gouty nephropathy and spinal cord compression. This study reports another major complication of gout, namely tophi deposition causing limited knee joint excursion. METHODS: Seven gout patients with limited knee joint excursion owing to tophi deposition were studied to reveal clinical features and magnetic resonance imaging (MRI) findings. None of the patients were able to assume a full squatting posture. RESULTS: No patients had visible subcutaneous tophi over the knee joints, except for one case in which a pea-sized subcutaneous tophus was noted. Additionally, two patients even lacked visible tophi elsewhere. All knee problems in the study group were initially regarded as being due to degenerative or other internal derangements, but MRI unexpectedly revealed multiple tophaceous depositions within and around the joint. CONCLUSIONS: Intra-articular and periarticular tophi limiting knee joint range of motion are a rare but important cause of walking disability in gout patients. Although most patients do not display visible subcutaneous tophi over the knee on physical examination, the differential diagnosis should consider intra-articular tophi and MRI is valuable in this clinical setting.