title: The femoral neck-shaft angle on plain radiographs: a systematic review.
abstract: OBJECTIVE
  The femoral neck-shaft angle (NSA) is an important measure for the assessment of the anatomy of the hip and planning of operations. Despite its common use, there remains disagreement concerning the method of measurement and the correction of hip rotation and femoral version of the projected NSA on conventional radiographs. We addressed the following questions: (1) What are the reported values for NSA in normal adult subjects and in osteoarthritis? (2) Is there a difference between non-corrected and rotation-corrected measurements? (3) Which methods are used for measuring the NSA on plain radiographs? (4) What could be learned from an analysis of the intra- and interobserver reliability?
  
  
  METHODS
  A systematic literature search was performed including 26 publications reporting the measurement of the NSA on conventional radiographs.
  
  
  RESULTS
  The mean NSA of healthy adults (5,089 hips) was 128.8° (98-180°) and 131.5° (115-155°) in patients with osteoarthritis (1230 hips). The mean NSA was 128.5° (127-130.5°) for the rotation-corrected and 129.5° (119.6-151°) for the non-corrected measurements.
  
  
  CONCLUSIONS
  Our data showed a high variance of the reported neck-shaft angles. Notably, we identified the inconsistency of the published methods of measurement as a central issue. The reported effect of rotation-correction cannot be reliably verified.
authors: Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Joseph-Stelzmann Str. 9, 50931, Cologne, Germany. christoph.boese@uk-koeln.de.
authors: Christoph Kolja
authors: CK
authors: Boese
authors: Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Joseph-Stelzmann Str. 9, 50931, Cologne, Germany.
authors: Jens
authors: J
authors: Dargel
authors: Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Joseph-Stelzmann Str. 9, 50931, Cologne, Germany.
authors: Johannes
authors: J
authors: Oppermann
authors: Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Joseph-Stelzmann Str. 9, 50931, Cologne, Germany.
authors: Peer
authors: P
authors: Eysel
authors: Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Joseph-Stelzmann Str. 9, 50931, Cologne, Germany.
authors: Max Joseph
authors: MJ
authors: Scheyerer
authors: Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Joseph-Stelzmann Str. 9, 50931, Cologne, Germany.
authors: Jan
authors: J
authors: Bredow
authors: Department of Trauma, Hand and Reconstructive Surgery, University of Giessen and Marburg, Marburg, Germany. lechler@med.uni-marburg.de.
authors: Philipp
authors: P
authors: Lechler
mesh_terms: D000328:Adult; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015995:Prevalence; D011859:Radiography / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: CCD; Caput-collum-diaphyseal angle; Hip anatomy; Hip arthroplasty; NSA; Neck shaft angle