A morphological adaptation? The prevalence of enlarged external occipital protuberance in young adults

Abstract

Enthesophytes are bony projections that arise from the sites of ligament, tendon or joint capsule attachment to a bone. They are seen rarely in radiographic findings in young adults, as these bony adaptations are assumed to develop slowly over time. However, in recent years, the presence of an enlarged external occipital protuberance (EEOP) has been observed frequently in radiographs of relatively young patients at the clinic of the lead author. Accordingly, the aim of this project was to assess the prevalence of an EEOP in a young adult population. Analysis involved a retrospective analysis of 218 lateral cervical radiographic studies of 18-30-year-old participants. Group A (n = 108; males = 45, females = 63) consisted of asymptomatic university students, while Group B (n = 110; males = 50, females = 60) were an age-matched mildly symptomatic, non-student population. The external occipital protuberance (EOP) size was defined as the distance from the most superior point of the EOP (origin) to a point on the EOP that is most distal from the skull. To avoid ambiguity, the threshold for recording the size of an EOP was set at 5 mm, and an EOP was classified as enlarged if it exceeded 10 mm. Reliability testing was also undertaken. Results indicated that an EEOP was present in 41% of the total population, with 10% of all participants presenting with an EOP ≥ 20 mm. An EEOP was significantly more common in males (67.4%) than in females (20.3%), with the mean EEOP size for the combined male population (15 ± 7 mm) being significantly larger (P < 0.001) than for females (10 ± 4 mm). The longest EEOP in the male population was 35.7 mm, while in the female population it was 25.5 mm. Additionally, the mean EEOP size for Group A (14 ± 7 mm) was also significantly greater (P = 0.006) than that recorded for Group B (12 ± 6 mm). This study identified that an EEOP is a condition that is prevalent in the populations tested. The age of the populations, and the prevalence of EEOP, suggest that biomechanical drivers for this phenomenon may be the main reason for this condition in these populations.

Enlarged External Occipital Protuberance in young French individuals’ head CT: stability in prevalence, size and type between 2011 and 2019

“…There are three types of EOP depending on its shape 2,3 : "flat type" (type 1), "crest type" (type 2) and "spine type" (type 3). Previous studies have shown that type 1 was more frequent in women and type 3 more frequent in men 2,4 . Type 3 can sometimes manifest as a subcutaneous scalp pseudotumor 5 .…”

Ultrasound assessment of the external occipital protuberance in young adults. Clinical implications

“…As shown in the study by Shahar et al, 8 the finding of osteophytes in the EOP by means of X-rays is increasingly frequent in daily clinical practice, with an incidence of 41%, affecting over 67% of men and 20% of women. Studies concerning cervical exostosis of the EOP are scarce and can be classified into radiological or anatomical studies.…”

“…Likewise, the authors have frequently observed that this finding in the EOP is present in asymptomatic subjects, in line with existing evidence. 8 The ultrasound finding of this exostosis may indicate that this insertion area of the upper trapezius muscle is a subjective area of high or repetitive mechanical traction. Thus, the ultrasound assessment, always associated to the patient's clinical situation, allows us to evaluate and plan our physiotherapy treatment to include preventive postural measures that could aggravate this finding.…”

“…A direct relationship is established with the habitual and prolonged usage of mobiles and tablets. 8 Due to the extensive media coverage, the authors subsequently published a rectification pointing out the observational nature of the study and therefore, objectively, no direct relationships could be established.…”

Is Bony Evidence of Enthesial Reaction Sufficient for Differential Diagnosis?

“…Alterations ofen theses (sites of ligament, tendon or capsule insertion) [1][2][3] have been suggested as markers of activity and pathology. Defined as bone reaction at sites of the insertions of tendons, ligaments and joint capsules [4,5], enthesial reaction has been variously considered to have a mechanical or inflammatory derivation [6][7][8][9].…”