title: The Modified Femoral Neck-Shaft Angle: Age- and Sex-Dependent Reference Values and Reliability Analysis.
abstract: Background. The femoral neck-shaft angle (NSA) is of high importance for the diagnostics and treatment of various conditions of the hip. However, rotational effects limit its precision and applicability using plain radiographs. This study introduces a novel method to measure the femoral NSA: the modified NSA (mNSA), possibly being less susceptible against rotational effects compared to the conventional NSA.Patients and Methods. The method of measurement is described and its applicability was tested in 400 pelvis computed tomography scans (800 hips). Age- and gender-dependent reference values are given and intra- and interrater reliability are analyzed.Results. The mean age of all 400 patients (800 hips) was 54.32 years (18-100, SD 22.05 years). The mean mNSA was 147.0° and the 95% confidence interval was 146.7°-147.4°. Differences of the mNSA between sexes, age groups, and sides were nonsignificant. The absolute difference between NSA and mNSA was 16.3° (range 3-31°; SD 4.4°); the correlation was high (0.738;p< 0.001). Overall, the intra- and interrater reliability were excellent for the mNSA.Interpretation. We introduced a novel concept for the analysis of the neck-shaft angle. The high reliability of the measurement has been proven and its robustness to hip rotation was demonstrated.
authors.affiliation: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors.forename: Christoph Kolja
authors.identifier: 0000-0002-5050-9345
authors.initials: CK
authors.lastname: Boese
authors.affiliation: Center of Orthopedic and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany.
authors.forename: Michael
authors.identifier: 0000-0002-9779-0277
authors.initials: M
authors.lastname: Frink
authors.affiliation: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Jostmeier
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital of Cologne, Cologne, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Haneder
authors.affiliation: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Dargel
authors.affiliation: Department of Orthopedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors.forename: Peer
authors.initials: P
authors.lastname: Eysel
authors.affiliation: Center of Orthopedic and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Lechler
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010388:Pelvis / Q000000981:diagnostic imaging; D016059:Range of Motion, Articular; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012399:Rotation; D012737:Sex Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult