Prevalence and Morphology of the Coracoclavicular Joint: An Osteological Study of 2,724 Subjects Using Univariable and Multivariable Logistic Regression Analyses

Abstract

Background: The coracoclavicular joint (CCJ) is an anomalous articulation between the surfaces of the inferior clavicle and superior coracoid and its etiology is controversial. Reportedly, symptomatic patients demonstrate significant functional limitations including shoulder abduction loss and potential for brachial plexus compression and impingement.Purpose: To determine the prevalence of CCJ across age, gender and ethnicity, and to identify clinically useful morphological characteristics.Methods: 2,724 subjects with intact clavicles and scapulae from the Hamann-Todd Osteological Collection were evaluated for the presence of CCJ. Logistic regression was used to determine the effect of age, height, gender, and race on prevalence of CCJ. 354 clavicles with CCJ were measured for size and location of the CCJ facet.Results: CCJ was observed in 9% of subjects. CCJ was more prevalent in African-Americans (12%) than Caucasian-Americans (6%) (p < 0.001) and more prevalent in females (11%) than males (8%) (p = 0.055). Facet location along clavicle length was consistent (average 25%, range 15–35%). But, facet location along clavicle width varied (average 60%, range 10–90%), with males having a more posterior location. For every 10-year increase in age, facet elevation (p = 0.001) and surface area (p < 0.001) increased.Conclusions: CCJ prevalence was 9% in our large osseous population, found more commonly in African-Americans and females. Facet location is predictable with respect to clavicle length, but less so along clavicle width. The clavicular facet may develop at some point in life and continue to grow in size after its appearance.Clinical Relevance: Presence of a CCJ represents a potential overlooked source of anterior shoulder pain and supracoracoid impingement. Epidemiologic and morphological characteristics presented in our study can aid in the identification, clinical understanding, and surgical excision of a symptomatic CCJ. Level of Evidence: Level IV.

A review of the coracoclavicular joint: Description, etiology, and clinical significance

“…By a large margin, males have a higher frequency of CCJ (661 cases) than females (223 cases) (Table 1). Interestingly, Harlow et al (2021) was the only study that found a higher frequency among females (10.8% vs. 8.1% for males). However, this difference did not appear in their multivariate model.…”

“…In studies that tallied the number of bilateral versus unilateral cases, roughly half of the individuals with a CCJ had one on both sides (Harlow et al, 2021;Kaur & Jit, 1991;Nalla & Asvat, 1995;Nehme et al, 2004;Totlis et al, 2018;Yammine & Assi, 2015). Chopra (3.7%).…”

“…Furthermore, if the triangular process does not make contact with the coracoid, one could argue that it does not represent a joint at all. Dry bone collections can also provide large sample sizes and permit the investigator to look for the presence of an articular facet at the conoid tubercle or on the coracoid process that otherwise would be missed in an X‐ray (Harlow et al, 2021). But, of course, they too lack any associated soft tissues for inspection.…”

“…Therefore, in order to facilitate comparison between all studies for this review, published results were sometimes converted to the number of CCJs among the total number of observable shoulders. This was not necessary for most osteological studies because one clavicle would represent one observable shoulder (except for Harlow et al (2021) and Nehme et al (2004) who examined complete skeletons). However, almost all results reported from the examination of radiographs or cadavers had to be converted and this is why the denominator in the frequency column is double the number in the N column for those studies in Table 1 (except for Nutter (1941) and Wertheimer (1948) who studied radiographs of individual shoulders and not chest radiographs).…”

“…In studies that tallied the number of bilateral versus unilateral cases, roughly half of the individuals with a CCJ had one on both sides (Harlow et al, 2021; Kaur & Jit, 1991; Nalla & Asvat, 1995; Nehme et al, 2004; Totlis et al, 2018; Yammine & Assi, 2015). Chopra et al (2017) found the lowest percent of bilateral CCJ, about one‐third, among their individuals from northern India while Cho and Kang (1998) report the highest with nine out of ten cases among their sample of Koreans.…”