Stemless versus stemmed anatomic total shoulder arthroplasty: a meta-analysis of randomized clinical studies at short term follow-up

Stemless total shoulder arthroplasty (TSA) implants were developed to counteract many of the complications and challenges associated with the stemmed humeral component. The purpose of this study was to evaluate the clinical efficacy, radiographic outcomes, and incidence of major complications of stemless implants relative to stemmed implants in the context of anatomic TSA using pooled data from randomized clinical studies. Eight databases were queried in October 2021 for randomized clinical studies directly comparing the outcomes between patients treated with stemless anatomic TSA, and conventional anatomic TSA with a stemmed humeral component. Clinical outcomes between groups were compared using a random effects model and a pooled weighted mean difference, a pooled standardized mean difference, or a pooled odds ratio. Five randomized clinical studies were identified with a total of 584 patients at final follow-up (range: 24.0-32.7 months) and an average age of 64.9 years (range: 62.1-69.0 years) at the time of surgery. There was no significant difference between the 2 groups for adjusted Constant–Murley Scores (P = .20), pooled patient reported functional outcomes (P = .41), forward flexion range of motion (P = .92), external rotation range of motion (P = .05), radiographic migration/subluxation of the humeral component (P = .52), infection risk (P = .89), odds of a revision surgery (P = .86), or odds of a subsequent reverse TSA (P = .68). For odds of a periprosthetic fracture (P = .07) and odds of developing radiolucency related to the humeral component (P = .06), there was a potential clinical benefit for the stemless component; however, this difference was not statistically significant for the current data set. This meta-analysis directly compared stemless and stemmed anatomic TSA implants and demonstrated no significant difference in the pooled results for any of the included clinical outcomes, radiographic outcomes, major complication outcomes, or revision surgery related outcomes between the 2 groups at early follow-up, although the small sample size may preclude in finding significance. These findings suggest that there are equivalent clinical outcomes of stemless anatomic TSA components and that these implants are safe, efficacious, and non-inferior relative to the current gold standard stemmed humeral implant. The data suggest that this is true for relatively younger anatomic TSA patients sampled from a population that is similar to those included in this meta-analysis.