title: Computed tomography-based morphologic and morphometric features of the coccyx among Arab adults.
abstract: METHODS
  Cross-sectional, retrospective.
  
  
  OBJECTIVE
  To identify morphological and morphometric features of the coccyx among adult Arabs.
  
  
  BACKGROUND
  Different sacrococcygeal morphologic features were found to be associated with coccydynia.
  
  
  METHODS
  Review of 202 computed tomographic scans of adult Arab subjects was done (mean age: 47.98 ± 16.46 yr). Sacrococcygeal morphological features including number of coccygeal segments, type of coccyx, joint fusion, joint subluxation, coccygeal spicule, coccygeal sacralization, ventral angulation of the terminal sacral segment (S5), and lateral deviation of coccygeal tip were recorded. Moreover, morphometric measurements including lengths and angles of the sacrococcygeal region were measured. Analysis of data was carried out using P value of less than 0.05 as the cutoff level of significance.
  
  
  RESULTS
  Three coccygeal segments were present in 138 (68.3%) of individuals. The majority of the subjects had coccyx type I (96; 47.5%), II (70; 34.7%), or III (31; 15.3%); type I being more common among males (P = 0.004). Bony spicule was present in 109 (54.0%) individuals. Joint fusion, joint subluxation, coccygeal sacralization, ventral angulation of S5, and lateral deviation of coccygeal tip were present in 38.6%, 31.7%, 34.2%, 38.1%, and 38.6% of the subjects, respectively. Joint subluxation and ventral angulation of S5 were more significantly present among females (P = 0.015, P = 0.014, respectively). The mean straight and curved lengths of the coccyx were 3.3 ± 0.7 cm and 3.7 ± 0.8 cm, respectively. The sacrococcygeal structures were longer in males than in females. The mean sacrococcygeal joint angle was 149.2°± 28.1°. Based on the morphometric measurements, the coccyx was more ventrally angulated among females.
  
  
  CONCLUSIONS
  The coccygeal morphology and morphometry of Arab adults share some similarities and differences with individuals of other ethnic backgrounds. Future studies should investigate the relation between these anatomic features with coccydynia among this population.
  
  
  METHODS
  3.
authors.affiliation: *Division of Orthopaedic Trauma, Department of Orthopaedic Surgery, Al-Razi Orthopaedic Hospital, Kuwait City, Kuwait †Department of Radiology, Al-Amiri Hospital, Kuwait City, Kuwait ‡Department of Radiology, Faculty of Medicine, Health Sciences Center, Kuwait University, Kuwait City, Kuwait §Division of Orthopaedic Surgery, Department of Surgery, Faculty of Medicine, Health Sciences Center, Kuwait University, Kuwait City, Kuwait; and ¶Department of Radiology, Mansoura University, Mansoura, Egypt.
authors.forename: Yousef Abbas
authors.initials: YA
authors.lastname: Marwan
authors.forename: Osama Mhawes
authors.initials: OM
authors.lastname: Al-Saeed
authors.forename: Ali Abdulla
authors.initials: AA
authors.lastname: Esmaeel
authors.forename: Osama Rabie Ahmad
authors.initials: OR
authors.lastname: Kombar
authors.forename: Abdulla Mohammad
authors.initials: AM
authors.lastname: Bendary
authors.forename: Mokhtar Elsayed Abdul
authors.initials: ME
authors.lastname: Azeem
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018912:Arabs; D003050:Coccyx / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D012445:Sacrococcygeal Region / Q000000981:diagnostic imaging*; D055815:Young Adult