In this article we report the case of a 46-years-old Portuguese woman admitted in our orthopaedic ward with right knee pain. Radiological findings were consistent with neuroarthropathy. After exclusion of the most common causes of polyneuropathy, Familial amyloid polyneuropathy (FAP) was diagnosed by the discovery of a mutation V30M on chromosome 18 by polymerase chain reaction on a fibroblast culture of her skin biopsy. FAP is one of many aetiologies of polyneuropathy. Although a rare disease, genetic screening in selected populations makes early diagnosis and prompt treatment of asymptomatic family members readily available.