The immediate effects of 5-minute high-force long axis distraction mobilization on the strain on the inferior ilio-femoral ligament and hip range of motion: A cadaveric study.

Background: The mechanical effects of hip joint mobilization on hip capsular-ligament tissue have never been studied.

Objective: To evaluate the strain on the inferior ilio-femoral (IFF) ligament after 5 min of high-force long-axis distraction mobilization (LADM) and to analyse the immediate effects on hip range of motion (ROM).

Design: Cross-sectional laboratory cadaveric study.

Methods: Thirteen hips hip joints were mobilized from nine fresh-frozen cadavers (mean age, 75.6 ± 7.8 years). High-force LADM in open-packed position was maintained during 5 min. Strain on IFF ligament was measured with a microminiature differential variable reluctance transducer at the beginning and just before the end of high-force LADM. Hip flexion, extension, abduction and internal rotation ROM were assessed using a universal goniometer before and after joint mobilization.

Results: The strain on IIF ligament increased 20.2 ± 8.5% after 5 min of high-force LADM, showing a significant increase (p = 0.004). Hip ROM also increased significantly (p < 0.05) with large effect sizes (d > 0.8).

Conclusion: The strain on IIF ligament and hip ROM increased significantly after 5 min of high-force LADM. The improvements on hip ROM appear to be related to the changes in the strain on capsular-ligament tissue after high-force LADM.