IntroductionIatrogenic nerve injury in orthopedic surgery can impair functional outcomes. During the last years, a steady increase in the number of performed reverse total shoulder arthroplasties has been reported and complications associated with this procedure are continuously described. Neurological complications, however, remain underreported. The aims of this study were to calculate the incidence of iatrogenic nerve injury after primary and revision reverse total shoulder arthroplasty in a large patient cohort, as well as identify associated patient-and surgery-related risk factors.Materials and methodsA retrospective review of our institution’s internal Reverse Total Shoulder Arthroplasty (RTSA) database from September 2005 to December 2019 was undertaken and 34 patients with iatrogenic nerve injuries were identified, resulting in a neurological complication rate of 2.6%. Group comparisons between patients with nerve injuries (n= 34) and the remaining cohort without nerve injuries (n= 1275) were performed to identify patient- and surgery-related risk factors.ResultsOf the 34 cases with iatrogenic nerve injury, damage to terminal nerve branches occurred in 21 patients, whereas a brachial plexus lesion was diagnosed in the other 13. Nerve revision surgery was necessary in four patients. At final follow-up 13 patients (45%) had residual motor deficits and 17 (59%) had residual sensory deficits. Higher numbers of previous surgeries of the affected shoulder correlated with subsequent nerve injury (p= 0.035). Operative time was significantly longer in patients, who developed a neurologic deficit, showing a correlation between duration of surgery and occurrence of nerve injury (p= 0.013). Patients with neurologic complications were significantly younger than patients without nerve damage (median 68 vs. 72 years,p= 0.017).ConclusionsIn specialists’ hands reverse total shoulder arthroplasty is a rather safe procedure regarding the risk of neurologic injury. However, multiple previous surgeries of the affected shoulder increase the risk of neurological complications. Cases with post-operative neurologic compromise are rare and usually recover well, with few patients suffering long-term functional deficits from iatrogenic nerve injury.Level of evidenceLevel III, retrospective cohort study.