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found in the currently used MOM bearings. To better understand the biological response toMOM wear debris we hypothesized that tissue from failed hips with implant corrosioncontained a different type of metal species when compared to those without corrosion.MethodTissue from patients with two types of MOM hip arthroplasty were analysed: Ultima that failedwith severely corroded femoral stems (n=12); and large diameter, current generation MOM hipsthat failed without visible corrosion (n=7). Comparison was also made to samples of cobalt,chromium and molybedanum standards.We used a high energy synchrotron xray beam to map and characterise the type of metal withinthe tissues. This enabled us to analyse the type of chemical in a situation that is as realistic aspossible: without staining; without the use of a vacuum; and the use of fresh frozen tissuesections with metals at relatively low concentrations. This could not have been achieved withouta synchrotron.ResultsComparison with standards revealed the chemical form of the chromium in the tissuessurrounding metal-on-metal hip replacements was chromium (III). This was similar for bothcorroded (Ultima MOM) and non-corroded (large diameter, current generation MOM) hips.This was chromium (III) phosphate in the non-corroded hips but because the concentration ofchromium was lower in the corroded hips it was difficult to differentiate chromium phosphatefrom oxide. There was some evidence of localistaion of cobalt and chromium, both in metallicform. One sample from corroded hips contained chromium (VI).ConclusionChromium (III) phosphate was the predominant metallic species in the tissues surroundingmetal-on-metal hip replacements. This may have arisen from corrosion, wear or a combinationof both.Friday, October 8, 2010, 13:30-14:10Session B12: Shoulder ArthroplastyComplications and Early Outcomes Following Reverse ShoulderArthroplasty Using a Prosthesis With a Lateral Center of Rotation*Samer Hasan - Cincinnati Sports Medicine and Orthopaedic Center - Cincinnati, USACassie M. Fleckenstein - Cincinnati SportsMedicine Research and Education Foundation -Cincinnati, USA*Email: sshasan@zoomtown.comThe reverse ball and socket shoulder replacement, employing a humeral socket andglenosphere, has revolutionized the treatment of patients with arthritis and rotator cuffinsufficiency. The RSP (DjO Surgical, Inc., Austin, Texas) is one such device, characterized byfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]