title: Logistic regression analysis of risk factors for femoral head osteonecrosis after healed intertrochanteric fractures.
abstract: OBJECTIVE
  To evaluate the potential risk factors of the development of femoral head osteonecrosis after healed intertrochanteric fractures.
  
  
  METHODS
  We retrospectively reviewed all patients who were operated upon with closed reduction and internal fixation for intertrochanteric fractures by our medical group from December 1993 to December 2012. Patients with healed fractures were identified. Age, gender, comorbidities favouring osteonecrosis, causes of injuries, fracture patterns, the location of the primary fracture line, time from injury to surgery, fixation methods, and the development of femur head osteonecrosis of these patients were summarised. Univariate and multivariate logistic regression analysis were performed to evaluate the correlation between potential risk factors and the development of femoral head osteonecrosis.
  
  
  RESULTS
  A total of 916 patients with healed intertrochanteric fractures were identified. Femoral head osteonecrosis was found in 8 cases (0.87%). According to the results of univariate logistic regression, a more proximal fracture line, fixation with dynamic hip screws and age were found to be statistically significant factors. The results of multivariate logistic regression analysis indicated that the statistically significant predictors of femoral head osteonecrosis were younger age (odds ratio [OR] = 17.103; 95% confidence interval [CI], 1.988-147.111), a more proximal fracture line (OR = 31.439; 95% CI, 3.700-267.119) and applying dynamic hip screw as the internal fixation (OR = 11.114; 95% CI, 2.064-59.854).
  
  
  CONCLUSIONS
  Regular follow-up is commended in young patients with a proximal fracture line who underwent closed reduction and internal fixation with dynamic hip screw, even though the bone had healed.
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai - China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Yin
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai - China.
authors.forename: Zhengliang
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai - China.
authors.forename: Jiagen
authors.initials: J
authors.lastname: Sheng
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai - China.
authors.forename: Changqing
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai - China.
authors.forename: Zhenhong
authors.initials: Z
authors.lastname: Zhu
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D001863:Bone Screws; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000009:adverse effects* / Q000379:methods; D017102:Fracture Healing / Q000502:physiology*; D006620:Hip Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000601:surgery; D020127:Recovery of Function; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult