Hip capsular strain varies between ligaments dependent on both hip position- and applied rotational force

Abstract

Purpose To noninvasively characterize the ligament strain in the hip capsule using a novel CT-based imaging technique. Methods The superior iliofemoral ligament (SIFL), inferior iliofemoral ligament (IIFL), ischiofemoral ligament (IFL) and pubofemoral ligament (PFL) were identified and beaded in seven cadavers. Specimens were mounted on a joint motion simulator within an O-arm CT scanner in − 15°, 0°, 30°, 60°, and 90° of flexion. 3 Nm of internal rotation (IR) and external rotation (ER) were applied and CT scans obtained. Strains were calculated by comparing bead separation in loaded and unloaded conditions. Repeated-measures ANOVA was used to evaluate differences in strain within ligaments between hip positions. Results For the SIFL, strain significantly decreased in IR at 30° (p = 0.045) and 60° (p = 0.043) versus 0°. For ER, there were no significant position-specific changes in strain (n.s.). For the IIFL, strain decreased in IR and increased in ER with no significant position-specific differences. For the IFL, strain increased with IR and decreased with ER with no significant position-specific differences. Finally, in the PFL there was a significant flexion angle-by-load interaction (p < 0.001; ES = 0.566), with peak strains noted at 60˚, however pair-wise comparisons failed to identify significant differences between positions (n.s.). Strain decreased in ER, with no significant position-specific differences. Conclusion The SIFL and IIFL limit hip external rotation with greater effect in higher flexion angles, while the IFL and PFL limit hip internal rotation. Following hip arthroscopy, consideration should be given to restricting external rotation as traditional capsulotomies cause injury to the SIFL and IIFL.

The Effectiveness of External Rotators and Ischiofemoral Ligament for the Prevention of Hip Dislocation in Hip Flexion Position: A Cadaveric Study

“…A previous study reported that the strain on the hip joint capsular ligament using a CT-based imaging technique showed that the ischiofemoral ligament was elongated during hip internal rotation. The length of the ischiofemoral ligament indicated the maximum length occurred at hip exion of 30°, increasing from -15° to 30°, and decreasing from 30° to 90° [18]. These anatomical data were consistent with our ndings.…”

The role of the iliofemoral ligament as a stabilizer of the hip joint

“…Recently Burkhart et al characterized the ligament strain in the hip capsule using a novel computed tomography (CT) based imaging technique. 25 Strains were calculated by comparing bead separation in loaded and unloaded conditions. For the SBILFL, strain significantly decreased in IR at 30° and 60° versus 0°.…”

“…For the IBILFL, strain decreased in IR and increased in ER with no significant position-specific differences. 25 …”

Impacts of external rotators and the ischiofemoral ligament on preventing excessive internal hip rotation: a cadaveric study

“…A previous study used a CT-based imaging technique to demonstrate that the strain on the hip joint capsular ligament was from an elongated ischiofemoral ligament during hip internal rotation. The ischiofemoral ligament length indicated that the maximum length occurred at a hip flexion of 30°, increasing from -15° to 30°, then decreasing from 30° to 90° [ 14 ]. These anatomical and biomechanical data were consistent with our findings that the ischiofemoral ligament was the primary contributor to hip stability by limiting the internal rotation between 0° and 60° of hip flexion, especially at 30°.…”