Reproducibility of Ultrasonographic Measurements of the Ulnar Nerve at the Cubital Tunnel.

The cross-sectional area (CSA) of the ulnar nerve is thought to be indicative of ulnar nerve entrapment. The purpose of the study was to determine reproducibility of ultrasonographic measurements of CSA of the ulnar nerve at the cubital tunnel in healthy adults. Two sonographers tested 69 participants using a standardized protocol. The inter-rater reliability intra-class correlation coefficient was 0.63, and the intra-rater reliability intra-class correlation coefficient was 0.85 for sonographer 1 and 0.88 for sonographer 2. The smallest detectable changes were 2.47 and 2.63 mm2 (25% and 26% of the mean CSA). The mean difference and 95% limits of agreement for sonographers 1 and 2 were -0.13 (-2.56 to 2.29) and -0.38 (-2.93 to 2.18). Based on the fair to good inter-rater reliability, the excellent intra-rater reliability and the clinical applicable intra-rater agreement, ultrasonography seems to be a valuable tool with which to assess the CSA of the ulnar nerve for diagnostic and evaluative purposes.

Reliability and agreement of ultrasonographic thickness measurements of the common lateral extensors of the elbow.

In individuals with lateral elbow tendinopathy, the thickness of the common lateral extensors tendon can be evaluated by musculoskeletal ultrasonography (MSU) for diagnostic and evaluative purposes. The reproducibility of these thickness measurements should be established before integrating it into daily practice. A test-retest design was used to determine the reproducibility of these measurements in the longitudinal and transverse planes. Seventy-three healthy participants were measured two times by two raters. Intra-class correlation coefficient values for inter-rater reliability for the longitudinal and transverse planes were 0.67 and 0.49. Intra-class correlation coefficient values for intra-rater reliability varied between 0.73 and 0.92. The smallest detectable change ranged from 0.50 to 0.78 mm and comprised 9.8%-16.3% of the mean thickness. MSU thickness measurement of the common lateral extensors tendon of the elbow has fair to excellent intra- and inter-rater reliability. Additionally, agreement is acceptable, which makes MSU a valuable tool for the evaluation of tendon thickness over time.