Fracture-Specific and Conventional Stem Designs in Reverse Shoulder Arthroplasty for Acute Proximal Humerus Fractures-A Retrospective, Observational Study

Abstract

Tuberosity healing and stem design can be outcome-dependent parameters in hemiarthroplasty for proximal humerus fractures (PHF). The relevance of fracture-specific stem design in reverse shoulder arthroplasty (RSA) is still a matter of debate. This retrospective study evaluates tuberosity healing and function for fracture specific stems (A) compared to conventional stems (B) in RSA for complex PHF in 26 patients (w = 21, mean age 73.5 years). Clinically, range of motion (ROM), Constant-Murley-Score (CS), Subjective Shoulder Value (SSV), and external rotation lag signs (ERLS) were evaluated. Healing of greater tuberosity (GT) and lesser tuberosity (LT), scapular notching, and loosening were examined radiologically. There were no statistical significant differences with regards to CS (A: 73 ± 11; B: 77 ± 9 points), SSV (A: 78% ± 11%; B: 84% ± 11%), external rotation (A: 18° ± 20°; B: 24° ± 19°), or internal rotation (A: 5.7 ± 2.2; B: 6.7 ± 2.8 CS-points) (p > 0.05). Mean forward flexion was superior for group A (p = 0.036). Consolidation of GT (82%) and LT (73%) was similar in both groups. Anatomical healing was slightly higher in group B (p > 0.05). Scapular notching was found in 27% (A) and 55% (B) (p > 0.05). RSA for PHF provides good to excellent clinical results. The quantitative and qualitative union rate for both cohorts was similar, indicating that fracture stems with open metaphyseal designs to allow for bone ingrowth do not improve tuberosity healing. ERLS correlates with a worse function in CS and ROM in all planes.

Keywords: 155°; fracture stems; fractures; greater tuberosity; lag sign; lesser tuberosity; proximal humerus; rehabilitation; reverse shoulder arthroplasty; stem design.

Figure 1

The figure show a 72-year-old female patient with a head split proximal humerus fractures (PHF) (a) treated with a fracture specific stem (b) four years after implantation (c). The figure shows a 70-year-old female patient with a four-part fracture (d) treated with conventional stem (e) five years after implantation (f).

Figure 2

Tuberosity repair with the conventional stem: After fracture exposure and placement of four sutures, two through the anterior and two through the posterior cuff, cementation was followed with stem implantation (a). Removal of excessive cement allowing bony tuberosity integration around the metaphysis was then followed by inlay positioning (b). Tensioning the anterior and posterior sutures through the fins (only for the conventional stem) (c) before aligning both tuberosities around the metaphysis of the stem (d). Closing the anterior and posterior sutures (e) and preventing the butterfly effect through the use of an additional, medial cerclage (f).

Figure 3

Tuberosity evaluation: A 76-year-old female patient treated with the fracture specific stem shows malunion of greater tuberosity (GT) and resorption of lesser tuberosity (LT) (a). A 68-year-old female patient with standard stem shows anatomical healing of LT and malunion of GT in true a/p (b) and axial (c) radiographs.

Figure 4

Study flow-chart with regards to patients treated with the fracture-specific stem (A) and the conventional stem design (B). (RSA—reverse shoulder arthroplasty, PHF—proximal humerus fracture).

Figure 5

Scatter plots for CS and active forward flexion for both stems with regards to follow-up time. Function for CS and forward flexion are lower in those patients with early follow-up. This statistical significance might be biased due to further improvement in function in the second year after operation.

Figure 6

A 70-year-old female patient presents at a six-year follow-up GT resorption in true a/p radiograph (a). Three years later, further resorption of the lateral cortex of the proximal humerus (*) has occurred (b). She was not entirely pain-free (VAS 2/15), however, presented excellent clinical function in abduction (c) and internal rotation (d). Better results in forward flexion, abduction, and SSV but also more pain is associated with this cortex resorption (p < 0.05).