Superior functional outcome following reverse shoulder arthroplasty compared to hemiarthroplasty for displaced three and four-part fractures in patients 65 and older: Results from a prospective multicentre randomised controlled trial: The Shoulder Hemiarthroplasty or Reverse Polarity Arthoplasty (SHeRPA) trial.

Background
Acute unreconstructible 3- or 4-part proximal humerus fractures can be treated with hemiarthroplasty or reverse polarity shoulder arthroplasty. Randomized trials using implants from multiple different companies or uncemented implants have found superior results with reverse polarity arthroplasty.
Hypothesis
We tested the hypothesis that cemented reverse polarity arthroplasty produces a superior outcome compared to cemented hemiarthroplasty using one implant system in patients aged 65 years and over at 12 months follow-up as measured with the Constant Score.
Methods
A prospective patient and assessor blinded multicenter randomized controlled trial was conducted of shoulder hemiarthroplasty or reverse polarity arthroplasty in patients aged 65 years and older with acute 3- and 4-part proximal humerus fracture not amenable to osteosynthesis. The primary outcome was the Constant Score at 12 months with total follow-up to 24 months. Block randomization by site was undertaken using random number generatio