title: Can the change in center-edge angle during pincer trimming be reliably predicted?
abstract: BACKGROUND
  Femoroacetabular impingement is recognized as a cause of hip pain in young adults and as a precursor to osteoarthritis although many questions persist regarding its management. One in particular is when to resect a pincer lesion and how much to resect. Instability can result from overresection and persistent impingement can result from underresection.
  
  
  OBJECTIVE
  We therefore determined the correlation between the change in center-edge (CE) angle and the amount of acetabular rim resection.
  
  
  METHODS
  We performed open acetabular rim trimming on 10 cadaveric hips. Radiographs were performed before and after rim resection every millimeter from 1 to 5 mm and we determined the CE angle. We performed linear regression to establish any correlation of the CE angle with the amount of resection.
  
  
  RESULTS
  The CE angle could be predicted by -1.3X + 1.5 (R(2) = 0.99), in which X = the amount of resection for 1 to 3 mm of resection. The average CE angle before resection was 35° ± 8.8° (range, 19°-58°).
  
  
  CONCLUSIONS
  The CE angle changes in a predictable way with acetabular rim trimming with larger amounts of resection resulting in greater changes in the CE angle.
  
  
  CONCLUSIONS
  The ability to accurately plan the amount of acetabular rim resection in hip arthroscopy by knowing the exact change in CE angle with amount of rim removal may help prevent overresection or underresection in pincer trimming.
authors.affiliation: Department of Orthopaedic Surgery, Mount Sinai Medical Center, 5 East 98th Street, 9th Floor, New York, NY 10029, USA. alexis.colvin@mountsinai.org
authors.forename: Alexis C
authors.initials: AC
authors.lastname: Colvin
authors.forename: Steven M
authors.initials: SM
authors.lastname: Koehler
authors.forename: Justin
authors.initials: J
authors.lastname: Bird
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000209:etiology / Q000517:prevention & control; D001178:Arthroplasty / Q000009:adverse effects / Q000379:methods*; D002102:Cadaver; D005260:Female; D057925:Femoracetabular Impingement / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D016014:Linear Models; D008297:Male; D010027:Osteotomy / Q000009:adverse effects / Q000379:methods*; D011859:Radiography; D016896:Treatment Outcome