title: Population variation in the incidence of the medial (hamate) facet of the carpal bone lunate.
abstract: Studies on the wrist joint have shown two types of the carpal bone lunate. In type II lunate there is a facet on the medial side of the lunate for articulation with the proximal pole of the hamate; such a facet is absent in type I lunate. Type II lunates have different kinematics, are more prone to clinically relevant degenerative changes in the hamato-lunate joint and are an uncommon cause of ulnar-sided wrist pain. Ninety plain radiographs showing postero-anterior views of the wrist (52 right and 38 left wrists) were studied in a population of Malays from Malaysia (mean age 48 years; age range 23 to 67 years) to determine the incidence of type I and type II lunates. Our findings were compared with those in other reports in the literature. In Malays, only 24 wrists (26.7%) showed a type II lunate compared to a reported incidence of 50% or more in populations from the Western world. Such a low incidence of type II lunate has not been reported before and may represent a genetic variation in Malays. Consequently, osteoarthritis of the hamate or lunate may play a less significant role in causing ulnar-sided wrist pain in Malays. In conclusion, the prevalence of type II lunate might vary in different population groups and further studies could be necessary to confirm this observation.
authors.affiliation: Department of Anatomy, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain. asdharap@gmail.com
authors.forename: Amol S
authors.initials: AS
authors.lastname: Dharap
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Lutfi
authors.forename: Marwan F
authors.initials: MF
authors.lastname: Abu-Hijleh
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry / Q000379:methods*; D002348:Carpal Bones / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D051225:Hamate Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D012667:Lunate Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008296:Malaysia / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011859:Radiography; D014955:Wrist Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*