Evaluation of rectus abdominis muscle strength and width of hernia defect in patients undergoing incisional hernia surgery

Background: The aim of this study was to analyze the strength status of the rectus abdominis muscle in patients with incisional hernia and the relationship between the width of the hernia defect and the strength of the rectus abdominis muscle.

Methods: This is a observational cohort study of patients with medial line incisional hernia (July-October 2022), classified as W2 according to the European Hernia Society (EHS). The data collected were demographic and clinical characteristics related to hernia, and measure of the rectus abdominis muscle strength using an isokinetic dynamometer and a strain gauge. We analyzed the relationship between hernia width and rectus abdominis muscle strength with correlation tests to adjustment by age, sex, BMI, and body composition.

Results: A total of 40 patients (64% female) with a mean age of 57.62 years (SD 11) were enrolled in the study. The mean BMI was 29.18 (SD 5.06), with a mean percentage of fat mass of 37.8% (SD 8.47) and a mean percentage of muscle mass of 60.33% (SD 6.43). The maximum width of the hernia defect was 6.59 cm (SD 1.54). In the male group, the mean bending force moment (ISOK_PT) was 94.01 Nw m (SD 34.58), bending force moment relative to body weight (ISOK_PT_Weight) was 103.32 Nw m (SD 37.48), and peak force (PK_90) was 184.71 N (SD 47.01). In the female group, these values were 58.11 Nw m (SD 29.41), 66.48 Nw m (SD 32.44), and 152.50 N (SD 48.49), respectively. Statistically significant differences were observed in the relationship between the data obtained with the isokinetic dynamometer and sex (p = 0.002), as well as between the data obtained with the isokinetic dynamometer and age (p = 0.006). Patients in the 90th percentile (P90) of rectus abdominis muscle strength also had smaller hernia defect widths (p = 0.048).

Conclusions: In this study, age and sex were identified as the most statistically significant predictor variables for rectus abdominis muscle strength. The width of the hernia defect exhibited a trend towards statistical significance.