title: [Uncertainty in the radiological evaluation of deformity in                     proximal humerus fractures].
abstract: BACKGROUND
  The accurate measurement of the deformity of proximal humerus fractures is essential for a proper treatment, particularly in the growing bone. Due to the local pain the correct projection in standard X-rays is difficult to achieve and, in contrast to other joints, cannot be verified in the X-ray. Even with the correct projections a mismeasurement can occur when the rotation is 45° to both planes. The aim of this study was to objectify the error sources and reveal starting points for an improvement.
  
  
  METHODS
  In a three-step study we initially developed a mathemathical formula in cooperation with the faculty of mathematics of the University of Duisburg-Essen. This formula was proved with X-ray imaging of a steel rod which was bent 120°, simulating a 60° deformity. X-ray images with different rotation and tilt were taken and compared with the values calculated with the above-mentioned formula. In the third step X-rays of a healthy shoulder in different rotation and tilt positions were presented to 2 orthopaedic and 3 radiological consultants. The aim was to determine the direction and amount of rotation and tilt.
  
  
  RESULTS
  The first theoretical step resulted in a mathematical formula which describes the optical deformation based on real deformation, tilt and rotation. The evaluation showed a mean difference of 0.5° (0-1.2°) between the calculated and the measured values. In the third step, evaluation of the X-rays of a shoulder showed that two in 50 (4 %) of the values were correct, in additional 28 cases (56 %) the tendency of the direction of the rotation was correct, the extent of the rotation was missed by 19.6° (0-60°). Ante- and retroversion were evaluated correctly in nine cases (18 %), the extent was missed by a mean of 23° (0-50°). In seven cases (18 %) the tendency for rotation and ante-/retroversion was correct, in 11 cases (22 %) one or both aspects could not be evaluated, in additional 8 cases (16 %) the extent could not be estimated.
  
  
  CONCLUSIONS
  Our results show that rotation and tilt of the proximal humerus cannot be estimated in shoulder X-rays and therefore a reliable measurement of the deformity of proximal humerus fractures is extremely unsafe. This problem is relevant for clinical practice because of the high likeliness of unaccurate projections in shoulder X-ray imaging after trauma. Especially for the growing bone the problem is evident, so that new ways of determining the deformity are mandatory.
authors: Orthopädie und Unfallchirurgie, Sana-Klinikum Duisburg, Klinik der Sana-Gruppe. dr.med.ackermann@gmx.de
authors: O
authors: O
authors: Ackermann
authors: M
authors: M
authors: Levine
authors: K
authors: K
authors: Eckert
authors: C
authors: C
authors: Rülander
authors: M
authors: M
authors: Stanjek
authors: C
authors: C
authors: von Schulze Pellengahr
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D016916:Joint Deformities, Acquired / Q000000981:diagnostic imaging*; D008297:Male; D008954:Models, Biological; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012782:Shoulder / Q000000981:diagnostic imaging*; D012784:Shoulder Fractures / Q000000981:diagnostic imaging*; D000070599:Shoulder Injuries