Prevalence of Bennett lesions based on sex, ancestry, and age in an osteologic collection of 5,662 scapulae

Background: Bennett lesions represent an extra-articular ossification on the posteroinferior aspect of the glenoid fossa and a potential source of posterior shoulder pain and limitation. The prevalence of Bennett lesions in the general population is unknown. Materials and methods: A total of 5,662 scapulae from 2,831 individual cadaveric specimens greater than 18 years of age at the time of death were examined. Matching scapulae were evaluated for Bennett lesions by two independent authors. Lesion prevalence was calculated and statistical analysis performed to evaluate differences in prevalence based on specimen sex (males vs. females), ancestry (African-American vs. Caucasian) and with increasing age at the time of death. Results: Bennett lesions were observed in 3.5% (n = 98 of 2,831) of specimens and 1.8% (n = 104 of 5,662) of scapulae. Interobserver reliability was 0.83, indicating excellent agreement among authors. Males possessed significant higher odds of possessing a Bennett lesion when compared to females (p =.009) and African-American specimens when compared to Caucasian specimens (p <.001). Each additional year of age was associated with a 1.4% increase in odds of a specimen having a Bennett lesion, while no significant increase in Bennett lesion prevalence was appreciated with increasing specimen age at the time of death when comparing male to female specimens (p =.07) or African-American to Caucasian specimens (p =.73). Conclusions: Bennett lesions were identified in 3.5% of osseous specimens and 1.8% of scapulae, with significantly higher prevalence in male and African-American specimens.