Intra‐Observer and Inter‐Observer Reliability of Shaft Condylar Angle and Lateral Capitellohumeral Angle: Evaluation Based on Reliability in Different Ages and Levels of Experience

OBJECTIVES: The aims of this paper were: (i) to examine the intra‐observer and inter‐observer reliability of the shaft‐condylar angle (SCA) and the lateral capitellohumeral angle (LCHA); (ii) to study the influence of experience level on the inter‐observer and intra‐observer reliability; and (iii) to determine the influence of the the age of the patients on reliability. METHOD: A retrospective cohort study was conducted. The study reviewed 81 elbow radiographs. The patients were aged between 2 and 13 years. All the images taken between 2000 and 2017 were independently measured by a senior pediatric orthopaedic surgeon, a pediatric orthopaedic surgeon, a pediatric orthopaedic fellow, an orthopaedic chief resident, a general practitioner, and a pediatric orthopaedic research assistant. Measurement was performed two times within a 2‐week interval. Inexperienced observers (general practitioner and research assistant) were supervised by senior pediatric orthopaedic surgeons for at least 30 radiographs before performing the measurement. Inclusion criteria were as follows: (i) age 2–13 years; and (ii) no previous elbow fracture. Exclusion criteria: elbow radiographs do not show true lateral view. The intraclass correlation coefficient (ICC) was used to calculate the reliability. RESULTS: The mean values of SCA and LCHA were 43° and 48°, respectively. For SCA, intra‐observer reliability was excellent (ICC = 0.85) for one observer, good (range = 0.73–0.76) for three observers, and moderate (0.59) for one observer. Inter‐observer reliability was moderate (0.48, 0.58), whereas the reliability categorized by age group showed excellent agreement (0.88–0.94). For LCHA, intra‐observer reliability was excellent (0.84–0.89) for three observers and good (0.66–0.80) for two observers. Inter‐observer reliability was moderate (0.44–0.45). Conversely, the reliability classified by age group showed excellent agreement (0.83–0.91). CONCLUSION: Intra‐observer reliability for LCHA and SCA were excellent to good for most observers. Inter‐observer reliability was moderate for LCHA and SCA. Reliability classified by age group showed excellent to good agreement. Reliability was influenced by the level of experience, especially for non‐medical staff.