Review Question - QID 216873

This elderly patient has a comminuted proximal humerus fracture. Surgical intervention with a reverse total shoulder arthroplasty (RSA) would have a center of rotation more medial than the native glenohumeral joint.

Proximal humerus fractures are common fractures often seen in older patients with osteoporotic bone following a ground-level fall on an outstretched arm. Treatment with sling immobilization is indicated for minimally displaced fractures with surgical fixation or arthroplasty indicated in more complex and displaced fractures. Use of a RSA is indicated in low-demand elderly individuals with non-reconstructible tuberosities and poor bone stock or those with a fracture-dislocation (and thus compromised vascularity remaining to the articular fragment), or a head-splitting fracture. The advantage of a reverse shoulder arthroplasty is that the center of rotation (COR) is moved inferiorly and medialized which allows the deltoid muscle to act on a longer fulcrum to increase shoulder abduction. The lateralized designs have a more lateralized COR than the medialized designs, but both have a more medialized COR than the native glenohumeral joint.

Boyle et al. compared the functional outcomes of RSA with hemiarthroplasty (HA) in patients with acute proximal humeral fractures. They reported that the RSA group had a significantly better 5-year outcomes scores than the hemiarthroplasty group. They concluded that patients with acute proximal humeral fractures who undergo RSA appear to achieve superior 5-year functional outcomes compared with patients who undergo hemiarthroplasty.

Cuff et al. prospectively evaluated patient outcomes following either HA or RSA for the treatment of comminuted proximal humeral fractures in elderly patients. They reported that radiographic healing of the tuberosities occurred in 61% of the patients in the HA group compared with 83% of the patients in the RSA group; 13% of patients in the HA group elected revision to RSA because of failed tuberosity healing and resultant shoulder pseudoparesis. They concluded that RSA resulted in better clinical outcomes and a similar complication rate compared with HA for the treatment of comminuted proximal humeral fractures in the elderly.

Bufquin et al. reviewed the use of RSA in patients that sustained a three- or four-part fracture of the proximal humerus. They reported that complications included reflex sympathetic dystrophy, neurological complications (most of which resolved), and anterior dislocation. They also noted displacement of the tuberosities in 53% of cases. They concluded that compared with conventional HA, satisfactory mobility was obtained despite frequent migration of the tuberosities.

Jobin et al. reviewed RSA use for the treatment of complex three- and four-part proximal humerus fractures in the elderly. They reported that repair and union of the greater tuberosity fragment during reverse shoulder arthroplasty demonstrates improved external rotation, clinical outcomes, and patient satisfaction compared with outcomes after tuberosity resection, nonunion, or resorption. They concluded that satisfactory results can be obtained with careful preoperative planning and attention to technical details.

Figure A is the radiograph of the shoulder depicting a 4-part proximal humerus fracture

Incorrect Answers:
Answer 2: Deloid muscle acts as a LONGER fulcrum and has more mechanical advantage to provide shoulder abduction
Answer 3: Tuberosity healing should try to be achieved with the use of a RSA for fracture, but this implant is less dependent on tuberosity healing than either a hemiarthroplasty or anatomic total shoulder arthroplasty
Answer 4: Poor results are noted with retroversion of the humeral component >40°
Answer 5: Repair of tuberosities is recommended despite the ability of RSA design to compensate for non-functioning tuberosities/rotator cuff deficiency. Repair of tuberosities have been shown to improve range of motion