title: The prevalence of cam-type femoroacetabular deformity in asymptomatic adults.
abstract: We performed a retrospective examination of the anteroposterior pelvic CT scout views of 419 randomly selected patients between April 2004 and August 2009 in order to determine the prevalence of cam-type femoroacetabular deformity in the asymptomatic population. The CT scans had all been undertaken for conditions unrelated to disorders of the hip. The frequency of cam-type femoroacetabular deformity was assessed by measuring the α-angle of each hip on the anteroposterior images. The α-angles were classified according to the Copenhagen Osteoarthritis Study. Among 215 male hips (108 patients) the mean α-angle was 59.12° (37.75° to 103.50°). Of these, a total of 30 hips (13.95%) were defined as pathological, 32 (14.88%) as borderline and 153 (71.16%) as normal. Among 540 female hips (272 patients) the mean α-angle was 45.47° (34.75° to 87.00°), with 30 hips (5.56%) defined as pathological, 33 (6.11%) as borderline and 477 (88.33%) as normal. It appears that the cam-type femoroacetabular deformity is not rare among the asymptomatic population. These anatomical abnormalities, as determined by an increased α-angle, appear to be twice as frequent in men as in women. Although an association between osteoarthritis and femoroacetabular impingement is believed to exist, a long-term epidemiological study is needed to determine the natural history of these anatomical abnormalities.
authors.affiliation: Rothman Institute, 925 Chestnut Street, Philadelphia, Pennsylvania 19107, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Jung
authors.forename: C
authors.initials: C
authors.lastname: Restrepo
authors.forename: M
authors.initials: M
authors.lastname: Hellman
authors.forename: H
authors.initials: H
authors.lastname: AbdelSalam
authors.forename: W
authors.initials: W
authors.lastname: Morrison
authors.forename: J
authors.initials: J
authors.lastname: Parvizi
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed