Changes over time in the strain on the inferior ilio-femoral ligament during a sustained 5-minute high-force long axis distraction mobilization: a cadaveric study

Abstract

Objective: To analyze the changes over time in the strain on the inferior ilio-femoral (IIF) ligament when a constant high-force long-axis distraction mobilization (LADM) was applied over 5 minutes. Design: A cross-sectional laboratory cadaveric study. Setting: Anatomy laboratory. Participants: Thirteen hip joints from nine fresh-frozen cadavers (mean age, 75.6 ± 7.8 years). Interventions: High-force LADM in open-packed position was sustained for a period of 5 minutes. Main outcome measure(s): Strain on IFF ligament was measured over time with a microminiature differential variable reluctance transducer. Strain measurements were taken at every 15s for the first 3min and every 30s for the next 2min. Results: Major changes in strain occurred in the first minute of high-force LADM application. The greatest increase in strain on the IFF ligament occurred at the first 15s (7.3 ± 7.2 %). At 30s, the increase in strain was 10.1 ± 9.6 %, the half of the total increase at the end of the 5-minute high-force LADM (20.2 ± 8.5 %). Significant changes in strain measures were shown to occur at 45s of high-force LADM(F= 18.11; p<0.001). Conclusion: When a 5-minute high-force LADM was applied, the major changes in the strain on IIF ligament occurred in the first minute of the mobilization. A high-force LADM mobilization should be sustained at least 45s to produce a significant change in the strain of capsular-ligament tissue.