title: Coxa profunda is not a useful radiographic parameter for diagnosing pincer-type femoroacetabular impingement.
abstract: BACKGROUND
  Coxa profunda is commonly viewed as a radiographic parameter that is indicative of pincer-type femoroacetabular impingement, and this finding can impact diagnostic and surgical decision-making. Validation of coxa profunda as a measure of pincer-type femoroacetabular impingement has not been rigorously analyzed. Our hypothesis was that coxa profunda is a very common radiographic finding in females and is not a finding that is specifically associated with pincer-type femoroacetabular impingement.
  
  
  METHODS
  A retrospective review was performed to determine the prevalence of coxa profunda in four groups of hips: those with acetabular dysplasia (fifty-eight hips), femoroacetabular impingement (fifty hips), symptomatic residual Legg-Calvé-Perthes deformities (sixteen hips), and asymptomatic hips (thirty-three). Coxa profunda was present when the floor of the acetabular fossa touched or was medial to the ilioischial line. The association between coxa profunda and hip disorder diagnosis, lateral center-edge angle, acetabular inclination, patient age, and sex was analyzed.
  
  
  RESULTS
  Coxa profunda was seen in 55% of the 157 hips and was slightly less common in the hips with acetabular dysplasia or residual Legg-Calvé-Perthes deformities (41% and 31%, respectively). Coxa profunda was evident in 76% of the thirty-three asymptomatic hips compared with 64% of the fifty hips with femoroacetabular impingement. Coxa profunda was more common in females than males (70% compared with 24%; p < 0.001). Acetabular overcoverage (a lateral center-edge angle of >40° or acetabular inclination of <0°) was seen in only 22% of hips with coxa profunda.
  
  
  CONCLUSIONS
  Coxa profunda should be considered a normal radiographic finding, at least in females. Coxa profunda is a nonspecific radiographic finding, seen in a variety of hip disorders and asymptomatic hips. The presence of coxa profunda is neither necessary nor sufficient to support a diagnosis of pincer-type femoroacetabular impingement.
authors: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors: Jeffrey J
authors: JJ
authors: Nepple
authors: Charles L
authors: CL
authors: Lehmann
authors: James R
authors: JR
authors: Ross
authors: Perry L
authors: PL
authors: Schoenecker
authors: John C
authors: JC
authors: Clohisy
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging* / Q000473:pathology; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000473:pathology; D006621:Hip Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007873:Legg-Calve-Perthes Disease / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D012737:Sex Factors; D055815:Young Adult