HypothesisWe hypothesized that certain operative conditions are more likely to require transfusion after reverse total shoulder arthroplasty (RTSA), but found no data comparing transfusion rates for traumatic, post-traumatic, and non-traumatic indications. MethodsRetrospective review identified 1083 patients with RTSA. After exclusion of revision and tumor cases, 783 patients were divided into 3 groups as follows: traumatic (acute fractures, fracture-dislocations), post-traumatic (nonunions, malunions, chronic dislocations), or non-traumatic (chronic rotator cuff insufficiency, glenohumeral arthritis with advanced glenoid wear). Demographics, operative indications, preoperative hematocrit, postoperative hematocrit, change in hematocrit, estimated blood loss, operative time, and blood transfusion rates were compared. We constructed a logistic regression model to determine the risk factors predicting blood transfusion. ResultsIndications were acute trauma in 83 patients, post-traumatic sequelae in 65, and non-traumatic conditions in 635. There were no statistically significant differences regarding body mass index (P = .5) or American Society of Anesthesiologists score (P = .11). There were more females in the traumatic and post-traumatic cohorts than in the non-traumatic cohort (P < .001). Surgical age was younger in the post-traumatic cases (P = .002). The overall frequency of blood transfusion was 4.6% (36/783): traumatic, 19% (16/83); post-traumatic, 17% (11/65); and non-traumatic, 1.4% (9/635). Both the traumatic and post-traumatic groups had significantly higher rates of blood transfusion than non-traumatic cases (P < .001). Preoperative hematocrit was lower in the traumatic group and estimated blood loss was higher in the traumatic and post-traumatic groups (P = .001). Post-traumatic patients experienced the greatest drop in postoperative hematocrit from preoperative levels. The multivariate logistic regression model showed that traumatic and post-traumatic indications for surgery were each an independent risk factor for blood transfusion, as was change in hematocrit, body mass index, surgical age, estimated blood loss, and preoperative hematocrit. ConclusionsOur results suggest that acute trauma as the indication for RTSA is the strongest independent risk factor for blood transfusion followed by post-traumatic sequelae. Surgeons should be aware of the markedly increased risk of transfusion based purely on these 2 surgical indications especially when in combination with other predictors of transfusion.