Incidence of posterior shoulder instability and trends in surgical reconstruction: a 22-year population-based study

The incidence of posterior shoulder instability (PSI) in the general population is not well defined. This study aimed to define the population-based incidence of PSI and describe trends in incidence and surgery rates. The study population included 143 patients (16 females, 127 males) diagnosed with new-onset PSI between January 1, 1994, and December 31, 2015. Medical records were reviewed to extract patient data. Age- and sex-specific incidence rates were calculated and adjusted to the 2010 United States population. Poisson regression was performed to examine trends by timeline, sex, and age. Age- and sex- adjusted annual incidence of PSI was 4.64 per 100,000 person-years, and posterior dislocation was 1.30 per 100,000 person-years. Peak PSI incidence for males and females was at 14 to 19 years (31.82 and 5.23 per 100,000 person-years). PSI incidence was higher in males than females (8.86 vs. 1.07 per 100,000 person-years, P