The influence of age, biological sex, anthropometrics, and neck characteristics on external occipital protuberance size.

Background: 40-45 % of the population presents with enlarged external occipital protuberances (EEOPs), which can lead to pain. EEOP occurrence is higher in younger males; however, the reason is debated. We used plane lateral radiographs to investigate how anthropometrics, age, biological sex, head and neck kinematics, and neck strength differ between those with and without an EEOP.

Methods: Data was compiled across four study samples, which included lateral radiographs taken in a neutral neck posture (n = 102, 50% females). An enlarged EOP was defined as being longer than 10 mm, and this threshold was used to classify participants as having a presence or absence of an EEOP. Statistical analyses were used to compare outcome measures between those with and without an EEOP presence for age, biological sex, skull angle, intervertebral joint angle (C1-C2 through C6-C7), and neck strength (flexion and extension).

Results: Twenty-four percent of participants (19 males and five females, p = 00.002 for biological sex differences) presented with an EEOP; only one was over 30 years old. There were no significant main effects on the skull and intervertebral joint angles, participant anthropometrics, or neck strength.

Conclusions: This study confirmed that enlarged EOPs are more prevalent in males; however, neck posture and other anthropometrics do not differ with the presence or absence of an EEOP.