*2.1. Study Population*

Between December 2009 and September 2020, 45 consecutive patients (m = 10, f = 35, mean age 75.8; range: 56–92 years at time of surgery) were identified with a head-split PHF. Of 45, 5 had sustained an additional glenoid rim fracture. All patients underwent RSA at one of two hospitals by one of three specialized shoulder surgeons. The indication for RSA was an unreconstructable PHF in an elderly patient population. All patients were retrospectively recruited via telephone invitation to attend a clinical follow-up examination. When patients could not be reached because the original contact details were no longer valid, we used the emergency contact details from medical records to gain further information on the patient's current location and ensure follow-up assessment of these cases. For those patients unable to attend the clinical assessment because of age, poor health and/or the inability to travel to one of our clinics, we evaluated shoulder function and status only via telephone and postal contact.

#### *2.2. Implant Description, Surgical Procedure and Postoperative Rehabilitation Protocol*

Patients were treated in a beach chair position using a deltopectoral approach. For all RSA patients, a Grammont type of prosthesis (155◦ humeral inclination) was used with either a conventional (*n* = 5) or fracture-specific stem design (*n* = 40) and open metaphysis to allow bone ingrowth (AEQUALIS™ REVERSED II or AEQUALIS™ REVERSED FX, Tornier/Stryker Inc., Kalamazoo, MI, USA) (Figure 1). In addition, we applied a hybrid cementing technique to enable bone ingrowth at the metaphysis. In each case, both the greater and lesser tuberosities were anatomically reattached using FiberWire® #5 sutures (Arthrex Inc., Naples, FL, USA) against the fin of the metaphyseal neck of the prosthesis as previously

described [14]. After surgery, the shoulder was immobilized in a sling for 14 days. Passive mobilization began on postoperative day 15 and active mobilization was undertaken six weeks post-RSA. All patients completed the same standardized rehabilitation protocol.

**Figure 1.** This figure shows a severe head-split PHF that has been treated with a RSA (**i**). All patients have received the same surgical treatment with a tuberosity refixation (**ii**). One year postoperatively, the greater tuberosity shows complete consolidation (**iii**). The *Fracture* stem (**iii**) shows a metaphyseal window to encourage bone ingrowth, whereas the *Reverse II* (**iv**) displays two holes for suturing the tuberosities. After 7 years of follow-up in another patient, however, the greater tuberosity has resorbed completely (**iv**).
