Changes Over Time in the Strain on the Inferior Iliofemoral Ligament During a Sustained 5-Minute High-Force Long-Axis Distraction Mobilization: A Cadaveric Study.

Objective: To analyze the changes over time in the strain on the inferior iliofemoral (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 9 fresh-frozen cadavers (mean age, 75.6±7.8 years; N=13).

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 15 seconds for the first 3 minutes and every 30 seconds for the next 2 minutes.

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 15 seconds (7.3±7.2%). At 30 seconds, 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 45 seconds of high-force LADM (F=18.11; P<.001).

Conclusions: 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 45 seconds to produce a significant change in the strain of capsular-ligament tissue.