title: How Often Does Femoroacetabular Impingement Occur After an Innominate Osteotomy for Acetabular Dysplasia?
abstract: BACKGROUND
  Femoroacetabular impingement is increasingly recognized as a cause of hip pain but its incidence after an innominate osteotomy for the correction of acetabular dysplasia has not been determined. This information would be essential for the orthopaedic surgeon because it has the potential to produce a poor outcome in the long term when trying to balance acetabular instability and overcorrection.
  
  
  OBJECTIVE
  The purposes of our study were (1) to determine the frequency with which clinically relevant femoroacetabular impingement (FAI) occurs after an innominate osteotomy for the treatment of acetabular dysplasia; (2) to determine risk factors for the development of FAI; and (3) to compare postoperative radiographic and clinical outcomes in patients having undergone an innominate osteotomy for the correction of acetabular dysplasia both with and without FAI.
  
  
  METHODS
  This was a retrospective review of 154 hips (132 patients) that had undergone an innominate osteotomy for acetabular dysplasia and were evaluated at a minimum followup of 10 years (mean = 12 years). Mean age at the time of surgery was 3 years, 114 hips had a concomitant open reduction, and 54 hips also had femoral shortening. One hundred eight hips had a Salter osteotomy and 46 had a Pemberton osteotomy. Radiographs were analyzed to determine the lateral center-edge angle (CE angle) and the presence of a crossover sign. The diagnosis of FAI was established when the CE angle was greater than 40°, there was a positive crossover sign, and the patient had groin pain when flexing the hip less than 90°. Comparisons between nonparametric variables were performed with a Mann-Whitney's U test. Categorical variables were compared with a chi-square test. Change in acetabular index (correction) was dichotomized considering 20° of correction as the cutoff point. Association is presented as odds ratio (95% confidence interval), and logistic regression was performed.
  
  
  RESULTS
  According to our criteria, 18 of 154 hips had FAI (12%). Of the 18 patients with FAI, 10 had undergone a Pemberton osteotomy (10 of 46 [22%]) and eight a Salter osteotomy (eight of 108 [7%]). A change in the postoperative acetabular index greater than 20° was associated with a greater likelihood of developing FAI. The mean postoperative acetabular index was lower for the group with FAI, for whom it was 20°, compared with the group without FAI, for whom it was 27° (p = 0.04). The mean Iowa Hip Score for the group with FAI was 85, whereas for those without FAI, it was 93 (p = 0.03).
  
  
  CONCLUSIONS
  FAI is not common after an innominate osteotomy for the treatment of acetabular dysplasia; however, overcorrection is related to a higher incidence. When FAI is present, it can affect the outcome. Overcorrection should be avoided when performing an innominate osteotomy for the treatment of acetabular dysplasia because it can create iatrogenic FAI and have an adverse effect on outcome.
  
  
  METHODS
  Level III, therapeutic study.
authors.affiliation: Shriners Hospital for Children, Av. Del Iman 257, Del. Coyoacán, Mexico City, Mexico. pablocastaneda@me.com.
authors.forename: Pablo
authors.initials: P
authors.lastname: Castañeda
authors.affiliation: Hospital German Díaz Lombardo, Mexico City, Mexico.
authors.forename: Carlos
authors.initials: C
authors.lastname: Vidal-Ruiz
authors.affiliation: Shriners Hospital for Children, Av. Del Iman 257, Del. Coyoacán, Mexico City, Mexico.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Méndez
authors.affiliation: American British Cowdray Medical Center, Mexico City, 04600, Mexico.
authors.forename: Diego Pérez
authors.initials: DP
authors.lastname: Salazar
authors.affiliation: American British Cowdray Medical Center, Mexico City, 04600, Mexico.
authors.forename: Armando
authors.initials: A
authors.lastname: Torres
mesh_terms: D000077:Acetabulum / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D057925:Femoracetabular Impingement / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006618:Hip Dislocation, Congenital / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007049:Iatrogenic Disease; D007223:Infant; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D010027:Osteotomy / Q000009:adverse effects* / Q000379:methods; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
references.citation: J Pediatr Orthop. 2007 Oct-Nov;27(7):788-95
references.pmid: 17878786
references.citation: Clin Orthop Relat Res. 2008 Feb;466(2):264-72
references.pmid: 18196405
references.citation: J Bone Joint Surg Br. 2009 May;91(5):589-94
references.pmid: 19407290
references.citation: Clin Orthop Relat Res. 2005 Sep;438:182-90
references.pmid: 16131889
references.citation: J Bone Joint Surg Am. 2009 Jan;91(1):210-21
references.pmid: 19122097
references.citation: Clin Orthop Relat Res. 1978 May;(132):82-7
references.pmid: 679558
references.citation: Instr Course Lect. 2001;50:229-38
references.pmid: 11372318
references.citation: J Bone Joint Surg Am. 2013 Feb 6;95(3):230-6
references.pmid: 23389786
references.citation: Orthopedics. 2011 Jan 01;34(2):86
references.pmid: 21323284
references.citation: Instr Course Lect. 2008;57:473-98
references.pmid: 18399603
references.citation: Instr Course Lect. 2006;55:145-58
references.pmid: 16958447
references.citation: J Pediatr Orthop B. 2002 Jan;11(1):34-40
references.pmid: 11866079
references.citation: J Am Acad Orthop Surg. 2007 Sep;15(9):561-70
references.pmid: 17761612
references.citation: J Bone Joint Surg Am. 2008 Nov;90 Suppl 4:47-66
references.pmid: 18984718
references.citation: J Am Acad Orthop Surg. 2008 Dec;16(12):689-703
references.pmid: 19056918
references.citation: Clin Orthop Relat Res. 1990 Sep;(258):33-40
references.pmid: 2203574
references.citation: Orthop Clin North Am. 1972 Mar;3(1):149-56
references.pmid: 5012578
references.citation: Clin Orthop Relat Res. 2014 Mar;472(3):1001-9
references.pmid: 24096458
references.citation: J Pediatr Orthop. 2011 Jul-Aug;31(5):530-3
references.pmid: 21654461
references.citation: J Bone Joint Surg Br. 1999 Mar;81(2):281-8
references.pmid: 10204935
references.citation: J Bone Joint Surg Br. 2009 Feb;91(2):162-9
references.pmid: 19190047
references.citation: J Bone Joint Surg Br. 1991 May;73(3):423-9
references.pmid: 1670443
references.citation: J Bone Joint Surg Am. 2008 Oct;90(10):2267-81
references.pmid: 18829926
references.citation: Clin Orthop Relat Res. 2015 May;473(5):1755-62
references.pmid: 25391418
references.citation: J Bone Joint Surg Am. 1965 Jan;47:65-86
references.pmid: 14256975
references.citation: Clin Orthop Relat Res. 2003 Dec;(417):112-20
references.pmid: 14646708
references.citation: J Bone Joint Surg Am. 1986 Jan;68(1):79-87
references.pmid: 3941122
references.citation: J Orthop Res. 2007 Jun;25(6):758-65
references.pmid: 17343286
references.citation: Clin Orthop Relat Res. 2009 Mar;467(3):608-15
references.pmid: 19089521
references.citation: J Bone Joint Surg Am. 2002 Feb;84(2):178-86
references.pmid: 11861722
references.citation: J Bone Joint Surg Am. 1966 Oct;48(7):1413-39
references.pmid: 5921797