title: Computer-assisted analysis of lower limb geometry: higher intraobserver reliability compared to conventional method.
abstract: Exact radiographic evaluation of lower limb alignment, joint orientation and leg length is crucial for preoperative planning and successful treatment of deformities, fractures and osteoarthritis. Improvement of the accuracy of radiographic measurements is highly desirable. To determine the intraobserver reliability of conventional analysis of lower extremity geometry, 59 long leg radiographs were randomly analyzed 5 times by a single surgeon. The measurements revealed a standard deviation between 0.36 degrees and 1.17 degrees for the angles mLPFA, mLDFA, MPTA, LDTA, JLCA and AMA (nomenclature according to Paley), and 0.94 mm and 0.90 mm for the MAD and leg length, respectively. Computer-assisted analysis with a special software significantly reduced the standard deviation of the mLDFA, MPTA, LDTA, JLCA (each p < 0.001), AMA (p = 0.032) and MAD (p = 0.023) by 0.05-0.36 degrees and 0.14 mm, respectively. Measuring time was reduced by 44% to 6:34 +/- 0:45 min (p < 0.001). Digital calibration by the software revealed an average magnification of conventional long leg radiographs of 4.6 +/- 1.8% (range: 2.7-11.9%). Computer-assisted analysis increases the intraobserver reliability and reduces the time needed for the analysis. Another major benefit is the ease of storage and transfer of digitized images. Due to the varying magnification factors on long leg radiographs, the use of magnification markers for calibration is recommended.
authors.affiliation: Trauma Department, Hannover Medical School (MHH), Germany. hankemeir.stefan@mh-hannover.de
authors.forename: S
authors.initials: S
authors.lastname: Hankemeier
authors.forename: T
authors.initials: T
authors.lastname: Gosling
authors.forename: M
authors.initials: M
authors.lastname: Richter
authors.forename: T
authors.initials: T
authors.lastname: Hufner
authors.forename: C
authors.initials: C
authors.lastname: Hochhausen
authors.forename: C
authors.initials: C
authors.lastname: Krettek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007866:Leg / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies