The authors reviewed 126 patients who underwent primary total shoulder arthroplasty for osteoarthritis. Eighty-three (67%) were available at an average followup of 3.2 years (range, 24-45 months). Forty received a conventional all-polyethylene pegged glenoid and 43 received a hybrid component. During the period in question, four of the participating surgeons used only one implant, and four used only the other; there was one high-volume surgeon in each of the study groups. Radiographs were taken at the 2-year followup and analyzed for radiolucent lines.
There were no significant differences in radiolucent lines, VAS pain scores, ASES scores or complications.
Comment: As we've pointed out in a prior post, studies that show no difference - especially those regarding new and more expensive technologies - are very important. It is great that these authors these authors provided us with this status report. As they state, longer followup may reveal differences between the two glenoid components, but at present there seem to be no advantages of the metal hybrid. As we've seen in early reports (see this one for example), components with polyethylene and metal are at risk because of the widely differing Young's moduli which creates stress at the junction between these two materials.
One technical point, as stressed in a prior post, we avoid cement between the face of the glenoid bone and the back of the glenoid component (shown below). This thin cement layer does not fix the component to the bone and, because it is brittle, is at risk of breaking and displacement with loss of support for the prosthesis.
We continue to use an all polyethylene component with a bone ingrowth peg as shown here.
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