title: Prognostic value of the sliding length of cephalocervical screws to predict the risk of non-union after osteosynthesis: a retrospective analysis of 86 patients with intracapsular femoral neck fractures.
abstract: BACKGROUND
  Here, we assessed the prognostic value of the early sliding length (ESL) for predicting the risk of non-union after internal fixation of femoral neck fractures (FNFs) by Dual SC Screws (DSCS).
  
  
  METHODS
  A retrospective analysis of 86 patients with intra-capsular FNFs was performed. They underwent osteosynthesis by DSCS at our institution between 2008 and 2013 with a minimum follow-up duration of 6 months. Preoperative displacement, fracture reduction quality, ESL of screws at 2 weeks postoperatively, and correlation of non-union with the ESL of screws were evaluated.
  
  
  RESULTS
  Bone union without complications was achieved in 74 patients (86.0%), whereas 12 patients (14.0%) showed non-union. The ESL was significantly longer in the non-union group (proximal 3.94 ± 2.79 mm, distal 4.03 ± 3.16 mm) than in the union group (proximal 0.98 ± 1.85 mm, distal 1.01 ± 1.84 mm, P = 0.0001* for proximal, P < 0.0001* for distal). The ESL was significantly associated with non-union, both in the proximal [P = 0.0002, unit odds ratio (OR) 1.58, 95% confidence interval (CI) 1.23-2.16] and distal screws (P = 0.0002, unit OR 1.53, 95% CI 1.21-2.02). The areas under the ROC curves for the ESL of proximal and distal screws were 0.845 and 0.867, respectively; the cut-off values to predict non-union were 1.0 mm (sensitivity 91.7% and specificity 74.3%) and 1.4 mm (sensitivity 83.3% and specificity 81.1%), respectively.
  
  
  CONCLUSIONS
  In this study, the ESL was a good predictor of postoperative non-union in patients with FNFs fixed by DSCS.
authors.affiliation: Department of Orthpaedics, Munakata Suikokai General Hospital, 5-7-1 Himakino, Fukutu, Fukuoka, 811-3298, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Hirakawa
authors.affiliation: Department of Orthopaedics, Kurume Unversity, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan. nakamura_hidehiro@med.kurume-u.ac.jp.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Department of Orthpaedics, Munakata Suikokai General Hospital, 5-7-1 Himakino, Fukutu, Fukuoka, 811-3298, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Minamitani
authors.affiliation: Department of Orthopaedics, Kurume Unversity, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan.
authors.forename: Ryuki
authors.initials: R
authors.lastname: Hashida
authors.affiliation: Department of Orthopaedics, Kurume University Medical Center, 155-1 Kokubu-machi, Kurume, Fukuoka, 839-0863, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Gotoh
authors.affiliation: Department of Orthopaedics, Kurume Unversity, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Shiba
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D005260:Female; D005265:Femoral Neck Fractures / Q000000981:diagnostic imaging / Q000534:rehabilitation / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000534:rehabilitation; D017102:Fracture Healing; D005599:Fractures, Ununited / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011474:Prosthesis Design; D012372:ROC Curve; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
keywords: Cephalocervical screw; Femoral neck fracture; Internal fixation