Hemiarthroplasty of the shoulder can be a safe and an effective treatment for pain in patients with rheumatoid arthritis. Many complications have been previously described in the literature; the most common of which are dislocation, loosening, periprosthetic fractures, and infection. We report a patient who presented with a discharging sinus over the tip of the acromium which was created by the displacement of the prosthesis and erosion of the AC joint and distal clavicle. The erosion of the distal clavicle and AC joint caused the remaining proximal clavicle to become mobile and displaced posteriorly; this spike of clavicle was then able to penetrate the trapezius muscle and eventually the skin causing an aseptic sinus. This was successfully treated with the exploration and excision of the distal 2 cm of the clavicle.