Pelvic Roll Back Can Trigger Functional Psoas Impingement in Total Hip Arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Radiology

Background:

• Iliopsoas impingement is a known complication following total hip arthroplasty (THA).
• Acetabular component malpositioning, particularly retroversion, is a common cause.
• Diffuse idiopathic skeletal hyperostosis (DISH) can lead to spinal stiffness and compensatory pelvic motion.

Observation:

• A case report details a patient experiencing functional iliopsoas impingement post-THA.
• The patient exhibited progressive pelvic roll back due to compensatory adaptation to a stiff thoracolumbar spine (DISH).
• This pelvic motion caused the psoas tendon to impinge over the pecten ossis pubis.

Findings:

• Functional iliopsoas impingement can arise from dynamic pelvic changes, not solely static component malposition.
• Pelvic roll back, especially when combined with decreased acetabular anteversion, can create a biomechanical conflict.
• The interplay between spinal mobility, pelvic orientation, and acetabular component alignment is critical.

Implications:

• Surgeons must consider dynamic pelvic changes and spinal comorbidities when planning THA.
• Avoiding the combination of pelvic roll back and reduced acetabular anteversion is crucial for preventing functional iliopsoas impingement.
• This case highlights the importance of a comprehensive biomechanical assessment in THA revision and primary surgery.