A prospective pilot study: In vivo stiffness comparison of light-elastic and strong-elastic off-the-shelf medical...

BackgroundStiffness is an independent determinant of compression therapy efficacy, beyond compression pressure alone. Three indices - static stiffness index (SSI), dynamic stiffness index (DSI), and walking pressure amplitude (WPA) - quantify stiffness. This study evaluated in vivo stiffness in eight compression stocking models to assess whether those marketed as "strong-elastic" differ significantly from those marketed as "light-elastic".MethodsIn a prospective, open-label pilot study, 10 healthy participants were each fitted with eight off-the-shelf AG II compression stocking models (4 "strong-elastic", 4 "light-elastic"). Continuous pressure monitoring was conducted at four standardized anatomical sites (B, B1, C, D) of the right lower extremity using the Picopress® system. A total of 320 measurement cycles were completed. Data were analyzed by comparing grouped results for "strong" vs. "elastic" stockings.ResultsThe SSI did not differ significantly between "strong-elastic" (stMCS) and "light-elastic" (elMCS) stockings at any site (p > .05). However, stMCS showed significantly higher DSI at sites B (4.55 ± 2.00 mmHg vs 3.90 ± 1.63 mmHg; p = .028), C (5.83 ± 2.28 mmHg vs 5.10 ± 1.82 mmHg; p = .015), and D (2.33 ± 1.16 mmHg vs 1.58 ± 0.87 mmHg; p < .001). For WPA, stMCS exhibited significantly higher stiffness at B1 (6.75 ± 2.26 mmHg vs 6.03 ± 2.27 mmHg; p = .018), C (4.33 ± 2.31 mmHg vs 3.73 ± 2.24 mmHg; p = .020), and D (6.25 ± 2.07 mmHg vs 4.23 ± 1.59 mmHg; p < .001). Mean lower leg circumference increased from 0.50 cm (D) to 1.05 cm (C), depending on movement.ConclusionAt B1, no significant differences in SSI or DSI were found between "strong-elastic" and "light-elastic" stockings, whereas WPA significantly differentiated both groups. Overall stiffness values exceeded previous reports, indicating both stMCS and elMCS possess substantial stiffness and likely improve venous hemodynamics.