Two types of humeral head (mono-polar and bi-polar) are available in humeral head replacement (HHR) but which type of head has advantage for treatment of rheumatoid arthritis shoulder is controversial.We experienced an RA patient, who had received a bipolar type HHR, and was suffering from prolonged shoulder pain and limitation of ROM caused by anterior subluxation of humeral head after operation. We thought a large volume of bipolar humeral head could induce posterior tightness and cause

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... or subluxation, and performed revision surgery on the patient using a small bio-modular humeral head (mono polar head) to loosen the posterior soft tissue. After the revision surgery, pain was releived and a good ROM was achieved. Bi-polar humeral head had the advantage gaining two motion surfaces in the gleno humeral joint and could diminish a destruction of glenoid bone. But, large volume of bi-polar head could induce soft tissue tightness. The operative findings of soft tissue tightness using trial head could give us important information to decide the type and size of humeral head at the time of HHR