title: Radiological outcome and intraoperative evaluation of a computer-navigation system for femoral nailing: a retrospective cohort study.
abstract: OBJECTIVE
  Intraoperative determinations of femoral antetorsion and leg length during fixation of femoral shaft fractures present a challenge. In femoral shaft fracture fixations, a computer-navigation system has shown promise in determining antetorsion and leg length discrepancies. This retrospective cohort study aimed to determine whether the use of computer navigation during femoral nailing procedures reduced postoperative femoral malrotation and leg length discrepancy, as well as the number of revision cases. We also sought to determine whether radiation exposure time was reduced when computer navigation was used.
  
  
  METHODS
  Of 246 patients treated for femoral shaft fractures between 2004 and 2012, we selected those that received postoperative computed tomography for rotation and leg length control. We included 24 patients who received navigation-assisted treatments and 48 who received unassisted treatments, matched for age, sex, and fracture type. All patients were treated by femoral nailing.
  
  
  RESULTS
  The groups showed significant differences in the mean (standard deviation (SD) delay before surgery (navigation-assisted vs. unassisted groups: 8.5 ± 3.2 vs. 5.2 ± 5.8 days; P<0.05) and surgery times (163.7 ± 43.94 vs. 98.3 ± 28.13 min; P<0.001). The groups were significantly different in the mean (SD) radiation exposure time (4.43 ± 1.35 vs. 3.73 ± 1.5 min; P=0.042), and were not significantly different in the postoperative femoral antetorsion difference (8.83 ± 5.52° vs. 12.4 ± 9.2°; P=0.056), or in the postoperative length discrepancy (0.92 ± 0.75 vs. 0.95 ± 0.94 cm; P=0.453). Four (16.7%) navigation-assisted and 15 (31.25%) unassisted surgeries got revision for torsion and/or length corrections.
  
  
  CONCLUSIONS
  Our results showed that, compared to unassisted femoral surgery, the computer-navigation system did not improve postoperative results or reduce radiation exposure. In the future, improvements in handling and application could facilitate the workflow and may provide better postoperative results. Currently, computer navigation may provide advantages for complicated or sophisticated cases, such as complex three-dimensional deformity corrections.
  
  
  METHODS
  Level III.
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany. Electronic address: hawi.nael@mh-hannover.de.
authors.forename: Nael
authors.initials: N
authors.lastname: Hawi
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Liodakis
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Suero
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Stuebig
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Musa
authors.initials: M
authors.lastname: Citak
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Krettek
mesh_terms: D000328:Adult; D017760:Bone Malalignment / Q000150:complications / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D003362:Cost-Benefit Analysis; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D005471:Fluoroscopy; D005594:Fracture Fixation, Intramedullary / Q000009:adverse effects / Q000295:instrumentation; D006801:Humans; D007870:Leg Length Inequality / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D011829:Radiation Dosage; D012189:Retrospective Studies; D012399:Rotation; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: Antetorsion; Computed tomography; Computer-assisted surgery; Femoral nailing; Navigation