The ReShAPE trial: Reverse Shoulder Arthroplasty for treatment of Proximal humeral fractures in the Elderly

Humeral neck fractures account for 5% of fractures of the appendicular skeleton and are the 3rd commonest osteoporotic fracture occurring with an incidence of 6.6 per 1000 person year. There is a unipolar age distribution with most occurring in the elderly independent population with osteoporosis who fall from a standing height. This incidence is set to increase in the next 20 years as a result of population growth. 49-85% of proximal humeral fractures are minimally displaced and are usually treated non-operatively with most having good outcome regardless of comminution. The poorer outcomes associated with displaced, multi-part fractures has led surgeons to investigate operative alternatives. Studies have not shown a clear benefit from surgical fracture fixation using a variety of implants compared to non-operative treatment because of fracture severity and the difficulty in achieving stable fixation in osteoporotic comminuted (fragmented) bone. Newer fixation devices (locking plates), which have some advantages in osteoporotic bone, have been subject to randomized trials, but have not been shown to improve outcome. Replacement of the fractured humeral head (hemiarthroplasty) is another treatment option, but has not been shown to be clearly superior to non-operative treatment or plate fixation. Recently, reverse total shoulder arthroplasty (replacement) has been used to treat these fractures, with several case series published. This prosthetic design negates the effect of tuberosity malunion and nonunion that are common after internal fixation or hemiarthroplasty by creating a mechanical advantage for the deltoid muscle to allow active forward elevation and abduction. Studies comparing reverse total shoulder arthroplasty to hemiarthroplasty have shown improved pain scores and functional outcomes after reverse shoulder arthroplasty. As a result the use of reverse shoulder arthroplasty for the treatment of proximal humeral fractures is increasing. Reverse shoulder arthroplasty has been reported to have a high complication rate including instability, loosening, poor rotation and radiological notching. The risk of complications and prosthetic longevity limits the use of reverse shoulder arthroplasty in young patients with most prostheses being inserted in patients over 65. No comparative trial has been performed to test the effectiveness of reverse total shoulder arthroplasty against non-operative treatment.