These authors conducted a prospective, multicenter, single-blinded randomized clinical trial comparing anatomic shoulder arthroplasty short-stemmed humeral (below left) or using stemless (below right) implants in 265 patients.
At two years
-the mean ASES score was 92.5 ± 14.9 for the stemless cohort and 92.2 ± 13.5 for the stemmed cohort -the proportion of shoulders without device-related complications was 92% for the stemless cohort
and 93% for the stemmed cohort
-no shoulder in either cohort had radiographic signs of loosening.
-range-of-motion measurements and ASES, SANE, and Constant scores did not differ significantly between cohorts at any time point within the 2-year follow-up.
Adverse events related to the humerus were more common with the short stem while adverse events related to the glenoid were more common with the stemless implant.
It is of note that patients were excluded from the study if they had the following characteristics that may limit the use of a stemless implant: inflammatory arthritis, small humeral neck, defects in humeral neck, humeral head cysts, osteonecrosis, post-tramatic arthritis, tuberosity malunion, osteoporosis, and osteomalacia. These conditions are not uncommon and are not contraindications to the use of a traditional stemmed humeral implant.
It is unclear whether either a stemless or a short stemmed humeral implant provide advantages over the more versatile canal-sparing impaction grafted standard stem with a low filling ratio as shown below.