The imaging techniques available to aid the diagnosis of ruptures of tendo Achillis, the rotator cuff and the tendon of tibialis posterior in rheumatoid patients are well described. However, ruptures of tendon or muscle at other sites are uncommon and may be overlooked. Diagnosis is often made by localised tenderness, swelling and a lack of active movement associated with a palpable defect. Clinical examination may be inconclusive and can be aided by imaging studies. We report two cases in which ruptures of a tendon were suspected, and ultrasound imaging demonstrated the palpable defect to be a cleavage plane in the subcutaneous fat – a ‘fat fracture’.