title: Effect of elbow position on radiographic measurements of radio-capitellar alignment.
abstract: OBJECTIVE
  To evaluate the effect of different elbow and forearm positions on radiocapitellar alignment.
  
  
  METHODS
  Fifty-one healthy volunteers were recruited and bilateral elbow radiographs were taken to form a radiologic database. Lateral elbow radiographs were taken with the elbow in five different positions: Maximal extension and forearm in neutral, maximal flexion and forearm in neutral, elbow at 90° and forearm in neutral, elbow at 90° and forearm in supination and elbow at 90° and forearm in pronation. A goniometer was used to verify the accuracy of the elbow's position for the radiographs at a 90° angle. The radiocapitellar ratio (RCR) measurements were then taken on the collected radiographs using the SliceOmatic software. An orthopedic resident performed the radiographic measurements on the 102 elbows, for a total of 510 lateral elbow radiographic measures. ANOVA paired t-tests and Pearson coefficients were used to assess the differences and correlations between the RCR in each position.
  
  
  RESULTS
  Mean RCR values were -2% ± 7% (maximal extension), -5% ± 9% (maximal flexion), and for elbow at 90° and forearm in neutral -2% ± 5%, supination 1% ± 6% and pronation 1% ± 5%. ANOVA analyses demonstrated significant differences between the RCR in different elbow and forearm positions. Paired t-tests confirmed significant differences between the RCR at maximal flexion and flexion at 90°, and maximal extension and flexion. The Pearson coefficient showed significant correlations between the RCR with the elbow at 90° - maximal flexion; the forearm in neutral-supination; the forearm in neutral-pronation.
  
  
  CONCLUSIONS
  Overall, 95% of the RCR values are included in the normal range (obtained at 90° of flexion) and a value outside this range, in any position, should raise suspicion for instability.
authors.affiliation: Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada.
authors.forename: Emilie
authors.initials: E
authors.lastname: Sandman
authors.affiliation: Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada.
authors.forename: Fanny
authors.initials: F
authors.lastname: Canet
authors.affiliation: Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Petit
authors.affiliation: Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada.
authors.forename: G-Yves
authors.initials: GY
authors.lastname: Laflamme
authors.affiliation: Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada.
authors.forename: George S
authors.initials: GS
authors.lastname: Athwal
authors.affiliation: Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada.
authors.forename: Dominique M
authors.initials: DM
authors.lastname: Rouleau
keywords: Elbow; Elbow dislocation; Elbow subluxation; Radiocapitellar ratio