Authors

  1. Gomez, Cameron L.

Article Content

Purpose/Hypothesis: To determine the presence of Diastasis Recti Abdominis (DRA), the normal morphological characteristics of the linea alba must be known. Accurate and reliable measurements of the linea alba enable the investigation of the relationship between DRA and subject characteristics. The purpose of this investigation was to develop techniques for measuring the length and width (inter-recti distance [IRD]) of the linea alba in cadavers and determine intra and inter-rater reliability. Number of Subjects: Five raters, who measured the dimensions of the linea alba on four cadavers were ranked. The two raters with the best intra and inter-rater reliability (least variability) measured nine additional cadavers. Materials/Methods: A minimally invasive abdominal wall dissection of four cadavers was performed to expose the linea alba and determine the presence of DRA. Pins were placed along the medial borders of the rectus abdominis at the umbilicus, 4.5 cm above, and 4.5 cm below the umbilicus. The IRD was measured at each of these sites. Upon finding a DRA, a thorough dissection was performed to measure the length and width of the entire linea alba and the size of the separation at five additional sites. Digital caliper micrometers were used for all measurements. Preliminary Reliability: To rank all five raters, the intra and inter-rater variance was calculated using a stratified mixed-effects model from two trials at each of the eight measurement sites. Final Reliability: The two raters ranking highest (lowest intra and inter-rater variance), measured nine additional cadavers. Mixed-effects models were fit separately for each of the initial three measurement sites on nine cadavers over three trials with these two raters. Results:Preliminary Reliability: The range of variability for all five raters was 1.3 to 2.4 mm. The two most reliable raters in the study did not deviate more than 1.6 mm at any site with an average intra-rater variability of 0.47 mm. Final Reliability: The fixed-effect rater-specific terms, which account for any impact the rater may have had on the measurement and allow for comparison between the cadaver variance and the variance of each rater, were equivalent, signifying excellent inter-rater reliability. The rater to cadaver variance ratios were no greater than 1.1*10-2, demonstrating that the variability of the raters' measurements were insignificant in comparison to the variability of the cadavers and the typical magnitude of the measurements. Therefore, intra-rater reliability was also excellent. Conclusions: This study demonstrates that cadavers can be used to reliably measure the dimensions of the linea alba and the size of a DRA. Clinical Relevance: Reliably measuring the linea alba in cadavers allows for further investigation into the prevalence of DRA in diverse populations.