Evaluation of stretching position by measurement of strain on the ilio-femoral ligaments: An in vitro simulation using trans-lumbar cadaver specimens

The ilio-femoral ligament is known to cause flexion contracture of the hip joint. Stretching positioning is intended to elongate the ilio-femoral ligaments, however, no quantitative analysis to measure the effect of stretching positions on the ligament has yet been performed. Strains on the superior and inferior ilio-femoral ligaments in 8 fresh/frozen trans-lumbar cadaveric hip joints were measured using a displacement sensor, and the range of movement of the hip joints was recorded using a 3Space Magnetic Sensor. Reference length (L0) for each ligament was determined to measure strain on the ligaments. Hip positions at 10° adduction with maximal external rotation, 20° adduction with maximal external rotation, and maximal external rotation showed larger strain for the superior ilio-femoral ligament than the value obtained from L0, and hip positions at 20° external rotation with maximal extension and maximal extension had larger strain for the inferior ilio-femoral ligament than the value obtained from L0 (p < 0.05). Superior and inferior ilio-femoral ligaments exhibited positive strain values with specific stretching positions. Selective stretching for the ilio-femoral ligaments may contribute to achieve lengthening of the ligaments to treat flexion contracture of the hip joint.