title: The hamate facet of the lunate: a radiographic study in an Arab population from Bahrain.
abstract: Based on the presence of a facet for the hamate two types of lunate bone have been described in the wrist; type I is without a facet for the hamate while type II bears a facet on the medial surface for articulation with the proximal pole of the hamate. Compared to type I lunates, type II lunates have been shown to have different kinematics, are more prone to clinically relevant degenerative changes in the hamato-lunate joint and may cause ulnar-sided wrist pain. The incidence of type II lunates seems to vary in different populations. Postero-anterior (PA) view of plain radiographs of the hand was studied in Arab subjects from Bahrain (n=381; 307 males and 74 females) to determine the incidence of type I and type II lunates. The mean age of the subjects was 31.1 years, the range being 18-80 years. In the population studied, only 148 (38.8%) of the 381 wrists showed type II lunate; 121 (31.7%) were found in males and 27 (7.1%) in females. There was no significant difference in the mean age of subjects with type I or type II lunates (P=0.16). There was no correlation between side and gender with the presence or absence of a hamate facet on the lunate. The incidence of type II lunate was much lower than reports in the literature of populations from the Western world, which could be attributed to a genetic variation in the Arab population in Bahrain. These data indicate that osteoarthritis of the hamate or lunate is less likely to be a cause of ulnar-sided wrist pain in Bahraini Arabs.
authors.affiliation: Department of Anatomy, College of Medicine and Medical Sciences, Arabian Gulf University, PO Box 22979, Manama, Kingdom of Bahrain. asdharap@gmail.com
authors.forename: A S
authors.initials: AS
authors.lastname: Dharap
authors.forename: H
authors.initials: H
authors.lastname: Al-Hashimi
authors.forename: S
authors.initials: S
authors.lastname: Kassab
authors.forename: M F
authors.initials: MF
authors.lastname: Abu-Hijleh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018912:Arabs; D001445:Bahrain; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D051225:Hamate Bone / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006801:Humans; D012667:Lunate Bone / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D017678:Sex Distribution; D014955:Wrist Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging