Lewis C, Loverro K, Khuu A. Kinematic differences during single-leg step-down between individuals with femoroacetabular impingement syndrome and individuals without hip pain. J Orthop Sports Phys Ther. 2018;48(4). 270-279.
This week’s post is a close continuation of our last blog post. This post will hopefully drive home the message that movement retraining is a significantly important piece of rehabilitation. The focus of this paper is on femoracetabular impingement (FAI). FAI is thought to occur when the femoral head (ball) prematurely contacts the acetabulum (socket). When the ball part of the hip joint prematurely contacts the outer rim of the socket the tissue in between (labrum and cartilage) can become damaged and produce pain that is commonly felt in the groin.
As the authors point out there has been a lot of research on different hip joint shapes(morphology) and the relationship between hip joint morphology and the occurrence of FAI and groin pain. On the other hand, there has not been much research on altered movement patterns that may be associated or contributing to FAI. These authors wanted to change just that.
The purpose of this study was to determine if there were differences in movement patterns in those with FAI and those without. Participants ranged in age from 14 years old to 50 years old. Participants in the FAI group had to be diagnosed via physical examination, clinical presentation, and imaging with some form of CAM, pincer, or mixed hip joint morphology. Individuals in the comparison group had to have no recent history of lower extremity pain and were picked as demographic matches.
3D motion analysis was used to measure various movement angles in the pelvis, hip, and knee while participants were instructed to perform a single leg step down. The authors believed the single leg step down would be challenging enough to identify movement discrepancies between groups of participants compared with other dual leg tasks such as the squat.
The results of the study were not completely surprising. The group with FAI had greater hip flexion and anterior pelvic tilt than the pain free group. Increased hip flexion and anterior pelvic tilt would put someone in a position more likely to experience FAI. This suggests that FAI is not necessarily solely a structural issue of the hip joint and that movement patterns may be a modifiable contributor to their pain. People with FAI may be able to retrain their movement patterns to avoid positions that cause impingement in the hip. The authors also found that women had greater hip flexion, adduction, and anterior pelvic tilt which is not surprising given that women typically have greater pelvic width and are more likely to experience impingement symptoms.
So it is likely that people who are experiencing FAI may have an underlying bony morphology but somewhere along the way they began moving in a way that set them up for impingement symptoms. There could be a number of reasons or causes for this altered movement, but it is important to note that movement patterns are changeable.