Spinopelvic challenges in primary total hip arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Radiology

Background:

• Acetabular cup orientation is critical for hip arthroplasty success, but a universal safe zone is lacking.
• Spinal conditions like arthrodesis or degenerative lumbar spine increase dislocation risk.
• The pelvis acts as a crucial link between hip and spinal motion, influencing both acetabular orientation and sagittal balance.

Purpose of the Study:

• To investigate the relationship between spinopelvic characteristics and hip arthroplasty dislocation risk.
• To identify key spinopelvic parameters predictive of instability.
• To establish optimal targets for spinopelvic parameters and cup orientation for improved surgical outcomes.

Main Methods:

• Evaluation of spino-pelvic motion through clinical examination and radiographic imaging.
• Analysis of static and dynamic spinopelvic parameters in healthy volunteers and patients.
• Correlation of specific spinopelvic parameters (pelvic tilt, sacral slope, lumbar lordosis, combined sagittal index) with dislocation risk.

Main Results:

• Significant variability in spinopelvic parameters exists, even in healthy individuals.
• Stiff or arthritic hips lead to altered pelvic tilt and compensatory lumbar lordosis changes.
• Specific static spinopelvic parameters (lumbo-pelvic mismatch >10°, high pelvic tilt >19°, low sacral slope) are associated with increased dislocation risk.

Conclusions:

• Achieving optimal combined sagittal index (CSI) between 205-245° (narrower for spinal disease) is vital.
• Coronal cup orientation targets (inclination/version 40/20 ±10°) must be met alongside spinopelvic optimization.
• Pre-operative assessment of spinopelvic parameters aids in planning and reducing hip arthroplasty dislocation.