Pelvic retroversion: a compensatory mechanism for lumbar stenosis

Area of Science:

• Spine surgery
• Orthopedics
• Neurosurgery

Background:

• Flexed lumbar spine postures can decompress the spinal canal, relieving neurogenic claudication.
• Pelvic retroversion can occur with distal lumbar flexion, potentially indicating compensation for lumbar stenosis.

Purpose of the Study:

• Investigate the underlying causes of pelvic retroversion in patients with flexible sagittal imbalance.
• Determine if pelvic retroversion is solely compensatory for sagittal imbalance or also for lumbar stenosis.

Main Methods:

• Compared 24 patients with flexible sagittal imbalance to 23 with fixed deformities using radiographic parameters.
• Analyzed pelvic tilt (PT) to pelvic incidence (PI) ratio for pelvic retroversion.
• Assessed lumbar lordosis changes between weight-bearing and non-weight-bearing images.

Main Results:

• The flexible cohort showed a greater preoperative diagnosis of lumbar stenosis (68%) compared to the fixed cohort (22%).
• Patients with lumbar stenosis exhibited a significantly greater PT/PI ratio, indicating more pelvic retroversion.
• No significant differences were found in C-2 or C-7 sagittal vertical axis between cohorts.

Conclusions:

• Flexible sagittal imbalance may involve pelvic retroversion as compensation for underlying lumbar stenosis.
• Preoperative evaluation should consider lumbar stenosis as a potential root cause for sagittal misalignment and pelvic retroversion.
• Pelvic retroversion can serve as a compensatory mechanism for both lumbar stenosis and sagittal imbalance.