title: A cadaver study comparing intraoperative methods to analyze lower limb alignment.
abstract: BACKGROUND
  Conventional intraoperative determination of lower limb alignment is essential for orthopedic surgical treatment. Current methods include the cable, alignment rod, and axis board methods.
  
  
  OBJECTIVE
  Are there differences in accuracy and reliability? What are the individual differences in applicability and radiation exposure?
  
  
  METHODS
  Twenty legs from 12 fresh-frozen cadavers were randomly selected. After fixation of the legs, measurements were performed using the cable, alignment rod, and axis board methods. Afterwards, all cadavers were subjected to CT scanning. Intersection of the mechanical leg axis with the tibia plateau was calculated as the percentage of the tibia plateau, beginning at the medial border (0%) and ending at the lateral border (100%). Results are presented as mean ± standard deviation (SD).
  
  
  RESULTS
  Compared with CT measurements, differences of the intersection at the tibia plateau were 3.9 ± 8.5% with the cable method, 3.6 ± 7.6% using the alignment rod, and 3.6 ± 9.6% using the axis board. The difference among all measurements was not statistically significant (p = 0.450). The average intersection of the mechanical axis was 43.95 ± 5.15% using the cable method, 43.93 ± 5.49% using the alignment rod, and 43.77 ± 5.92% using the axis board. CT measurements revealed an average intersection of 42.46 ± 5.22%. There was no statistically significant difference among conventional results (p = 0.976). We demonstrated good intraobserver reliability for all three methods (cable method, ICC = 0.97; alignment rod, ICC = 0.95; and axis board, ICC = 0.96). There were no statistically significant differences regarding radiation time (p = 0.349) or dose area product (p = 0.823).
  
  
  CONCLUSIONS
  All described measurements demonstrated valid measurement of lower limb alignment. With minimal effort, all three methods present a practical and uncomplicated way to control the mechanical axis.
authors.affiliation: Trauma Department of the Hannover Medical School (MHH), Carl-Neuberg-Str. 1, 30625, Hannover, Germany, hawi.nael@mh-hannover.de.
authors.forename: Nael
authors.initials: N
authors.lastname: Hawi
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Liodakis
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Suero
authors.forename: Rupert
authors.initials: R
authors.lastname: Meller
authors.forename: Musa
authors.initials: M
authors.lastname: Citak
authors.forename: Christian
authors.initials: C
authors.lastname: Krettek
mesh_terms: D002102:Cadaver; D004867:Equipment Design; D019544:Equipment Failure Analysis; D057918:Fiducial Markers; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D016343:Monitoring, Intraoperative / Q000295:instrumentation* / Q000379:methods; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods
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