Improved outcomes of older patients with acute and displaced proximal humerus fractures treated with window bone ingrowth fracture-specific stem reverse shoulder arthroplasty

Background The optimal treatment of displaced proximal humerus fractures (PHFs) in the older people population remains controversial. Reverse shoulder arthroplasty (RSA) is a popular surgical treatment option that provides improved and reproducible results. However, the relevance of fracture-specific stem designs for RSA to improve tuberosity consolidation and shoulder function remains debatable.Methods This study included all patients 70 years or older with acute and displaced PHFs primarily treated with RSA at a single institution in Portugal, between January 2010 and December 2019 who participated in a minimum follow-up of 2 years.Results A total of 112 patients (15 men and 97 women) with a median clinical follow-up of 52 months were included. The mean age at the time of fracture was 78.6 years. All fractures were classified as Neer types 3 and 4 (n = 50 and n = 62, respectively). A window bone ingrowth fracture-specific stem was used for 86 patients, and a conventional humeral stem was used for 26 patients. Regarding the tuberosity fixation technique, 76 tuberosities were attached using technique A (according to Boileau's principles), 36 tuberosities were attached using technique B (not following Boileau's principles) and 11cases were classified as technique C (if fixation was not possible). The overall survival rate during the 2-year follow-up was 88.2%; however, this decreased to 79% at 5 years. Only three patients had complications (two infections and one dislocation) requiring revision surgery. In the multivariable analysis, the tuberosity fixation technique (P = 0.012) and tuberosity anatomical consolidation (P < 0.001) were associated with improved Constant scores (median Constant Score 62.67 (technique A), 55.32 (technique B), 49.70 (technique C). Fracture-specific humeral implants (P = 0.051), the tuberosity fixation technique (P = 0.041), tuberosity anatomical consolidation (P < 0.001), and dementia influenced the achievement of functional mobility (P = 0.014). Tuberosity anatomic consolidation was positively associated with bone ingrowth fracture-specific humeral implants (P < 0.01) and a strong tuberosity fixation technique (P < 0.01).Conclusion RSA is used for complex and displaced fractures of the proximal humerus in older patients. Dementia was negatively correlated with functional outcomes. A window bone ingrowth fracture-specific stem combined with strong tuberosity fixation can yield better clinical and radiological results.