Controversy exists regarding the ideal patient/elbow positioning for optimal magnetic resonance imaging in patients being evaluated for ulnar collateral ligament (UCL) injuries. The objectives of this study are to determine which of three commonly utilized patient positions provides optimal imaging of the UCL, superiority in terms of patient comfort, and provides the highest intraobserver and interobserver reliability in assessing the ligament. Our hypothesis is that optimal positioning can lead to better evaluation of the ligament, reduce patient discomfort and decrease motion artifact providing better scans, and potentially reduce the necessity for MR arthrography. Randomized controlled trial, Multirater agreement study
Fifteen subjects with each underwent 3-Tesla magnetic resonance imaging of the elbow in three commonly utilized positions in a randomized order. All subjects filled out a post-scan comfort questionnaire after each position. Each of the imaging sequences was reviewed by seven observers; one musculoskeletal radiologist and six orthopaedic surgeons who had completed a sports medicine fellowship. Two of the observers graded the images at two different time points. Multirater and intrarater agreement was calculated based on the observed agreement, the Fleiss kappa coefficient for interrater reliability, and Cohen's kappa statistic for intrarater agreement.
The supine/forearm pronated position was significantly more comfortable than supine/forearm supinated (p=0.023) and prone/forearm supinated (p=0.018). In the supine/forearm pronated position, there was a 69% interrater observed agreement (Kappa=0.41) and a 69% intrarater observed agreement (Kappa=0.39). For this position, the orthopaedic surgeons agreed with the radiologist 66% of the time. In the supine/forearm supinated position, there was a 59% interrater observed agreement (Kappa=0.14) and a 68% intrarater observed agreement (Kappa=0.24). For this position, the orthopaedic surgeons agreed with the radiologist 38% of the time. In the prone/forearm prone position, there was a 68% interrater observed agreement (Kappa=0.37) and a 69% intrarater observed agreement (Kappa=0.41). For this position, the orthopaedic surgeons agreed with the radiologist 54% of the time.
Non-contrast magnetic resonance imaging of UCL is most comfortable for patients in the supine/forearm pronated position. This position also demonstrated the highest agreement between orthopaedic surgeons and the musculoskeletal radiologist. Grading of the intact UCL was reliable and reproducible in the supine/forearm pronated position and the prone/forearm supinated position.
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