title: Impact of triple pelvic osteotomy on contact stress pressure distribution in the hip joint.
abstract: OBJECTIVE
  We studied changes of contact stress distribution in the hip joint after Tonnis triple pelvic osteotomy applied in the treatment of dysplasia and hip joint incongruence in adolescents.
  
  
  METHODS
  In a group of 75 patients, 54 (72 %) female, who underwent surgery by triple pelvic osteotomy in adolescence for developmental disorder of the hip and avascular necrosis of the femoral head, a three-dimensional hip joint model was used based on the radiography of the pelvis with hips. The following biomechanical parameters were calculated: resultant hip force normalised to body weight (R/Wb), inclination of the resultant hip force (θ-R), the position of the stress pole (θ), peak contact hip stress (Pmax), and peak contact hip stress normalised to body weight (Pmax/Wb). Gait quality was also assessed.
  
  
  RESULTS
  After surgery the Wiberg CE angle was increased by 17.85° (114 %), resultant hip force normalised to body weight (R/Wb) was decreased by 0.107 (3.3 %), the position of the stress pole was shifted medially by 27.59° (63.5 %), and peak contact hip stress normalised to body weight (Pmax/Wb) was decreased by 2249.74 (55.9 %). Waddling gait was reduced from 17 (23.9 %) to four cases (5.6 %). All changes were statistically highly significant (p<0.01).
  
  
  CONCLUSIONS
  The effect of Tonnis triple pelvic osteotomy lies in the improvement of stress distribution across the acetabular cartilage of the hip joint, thus slowing down the degenerative damage of the hip joint.
authors.affiliation: University of Belgrade, Belgrade, Serbia. zvukasin@beotel.net
authors.forename: Zoran
authors.initials: Z
authors.lastname: Vukasinovic
authors.forename: Dusko
authors.initials: D
authors.lastname: Spasovski
authors.forename: Veronika
authors.initials: V
authors.lastname: Kralj-Iglic
authors.forename: Jelena
authors.initials: J
authors.lastname: Marinkovic-Eric
authors.forename: Igor
authors.initials: I
authors.lastname: Seslija
authors.forename: Zorica
authors.initials: Z
authors.lastname: Zivkovic
authors.forename: Vesna
authors.initials: V
authors.lastname: Spasovski
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D010027:Osteotomy / Q000379:methods*; D011312:Pressure; D011859:Radiography; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D016896:Treatment Outcome