Pelvic tilt in the sagittal plane has been closely correlated with the range of motion of the hips and with the biomechanics of femoroacetabular impingement. The theoretical basis is that anterior or posterior tilt of the pelvis can increase or decrease the range of motion, or even worsen the pathology of femoroacetabular impingement. Physiotherapy is a conservative way of managing femoroacetabular impingement syndrome, and one approach is to attempt to alter pelvic tilt with appropriate exercises.
A new study examined the effect of changes in pelvic tilt and in hip adduction on the hip's range of motion.
Ten hips with symptoms of femoroacetabular impingement were used, in which impingement was reproduced in two positions: at 20° of internal rotation with 100° of flexion and 10° of adduction, and at 40° of internal rotation with 35° of flexion and 10° of adduction. The degree of internal rotation was measured at the point of bony impingement. Each reproduction was carried out in the neutral position and at 5° and 10° of anterior and posterior pelvic tilt. The hip was then placed in 10° of abduction and all the movements were repeated.
With the pelvis in neutral tilt, impingement occurred at 4.3 ± 8.4° of internal rotation in the position of maximum flexion. An increase in anterior pelvic tilt led to a loss of internal rotation and therefore to an earlier onset of femoroacetabular impingement, while an increase in posterior tilt led to an increase in internal rotation and a later onset of femoroacetabular impingement. In the position of maximum flexion, abduction gave greater internal rotation before femoroacetabular impingement occurred. Placing the hip in abduction, with the pelvis in posterior tilt, produced a combined effect that increased internal rotation compared with the pelvis in neutral tilt. The range of motion in the mid-flexion position was not affected by any combination of pelvic tilt and adduction or abduction.
The authors concluded that abduction and posterior pelvic tilt increased the impingement-free range of motion of hips with femoroacetabular impingement. The conclusion drawn was therefore that physiotherapy rehabilitation aimed at altering pelvic tilt may reduce the frequency of femoroacetabular impingement and limit further wear of the joint.
Source: “Journal of American Academy of Orthopaedic Surgeons”, May 2020