What question did this study set out to answer?

This study aims to clarify the biomechanical connections among the hip, pelvis, and lumbar spine.

April 4, 2026Open Access

Defining The Relationship Between The Hip, Pelvis, and Lumbar Spine

Key Points

This study aims to clarify the biomechanical connections among the hip, pelvis, and lumbar spine.
Cohort of fifty healthy subjects aged 18-35 years
Participants underwent three lateral radiographs (standing, seated, flexed-seated)
Measurements included sacral slope (SS), pelvic-femoral angle (PFA), and lumbar lordosis (LL)
Pearson correlations analyzed relationships with significance set at p<0.05
Average participant age was 25.7 years with a BMI of 24.1 kg/m²
Each degree of hip flexion decreased lumbar flexion by 0.84 degrees (R=-0.75)
PFA negatively correlated with SS, with each degree increase in PFA yielding a decrease of 0.71 in SS (R=-0.85)
SS and LL showed strong correlation; a 1-degree increase in LL resulted in a 0.63 increase in SS (R=0.85)

Abstract

Introduction: While the hip, pelvis, and lumbar spine are known to move synchronously, their exact relationship has yet to be determined.The aim of this study was to define the biomechanical relationship between the hip, pelvis, and lumbar spine. Methods:A cohort of fifty healthy subjects between 18-and 35-years-old were recruited to participate, including 25 males and 25 females.Exclusion criteria included presence of back or hip pain, inability to stand upright or sit with hips flexed to 90, history of ankylosing spondylitis, femoroacetabular impingement, or prior hip or spine surgery.Three lateral radiographs were obtained for each patient, including standing, relaxed seated, and the flexed-forward seated views.Radiographic variables measured included sacral slope (SS), pelvic-femoral angle (PFA), and lumbar lordosis (LL).Calculations included the change in SS (SS), the change in PFA (PFA), the change in LL (LL).Pearson correlations were used to determine the relationship between SS, PFA, and LL with significance set to p<0.05. Results:The average age of participants was 25.702.34years with a body mass index (BMI) of 24.103.02kg/m 2 .For every degree increase of hip flexion, lumbar flexion decreased 0.84 (R=-0.75,p<0.001).Similarly, PFA was strongly negatively correlated with SS, with every degree increase of PFA yielding a decrease of 0.71 in SS (R=-0.85,p<0.001).SS was strongly correlated with the LL.For every degree that LL increased, SS increased 0.63 (R=0.85,p<0.001). Conclusion:Motion between the hip, pelvis, and lumbar spine is highly correlated.For every degree increase of hip flexion, the pelvis tilts posteriorly 0.71, causing the lumbar spine to flex 1.58 degrees to maintain upright posture.For every degree increase of hip flexion, the lumbar spine decreases flexion 0.86 degrees.Given the increased interest and clinical applicability of spinopelvic biomechanics in the spine community, these definitions are essential to moving forward with research in this topic.

KI fragen

Bookmark

View Full Paper