Subsidence analysis of a cementless short stem THA using EBRA-FCA - A seven-year prospective multicentre study

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Metaphyseal fixation in short stem total hip arthroplasty (THA) offers minimally invasive benefits, reduced bone removal, and improved load transfer.
• Short stems aid in anatomic restoration of leg length, femoroacetabular offset, and center of rotation.
• Potential concerns include impaired stability, leading to axial migration and aseptic loosening.

Purpose of the Study:

• To evaluate the long-term clinical outcomes of a calcar-guided short stem in THA.
• To analyze the migration pattern and stability of this specific short stem design over time.

Main Methods:

• Prospective multicenter study involving 213 patients (224 THAs) followed for up to 84 months.
• Clinical assessment using Harris Hip Score, VAS for pain, and satisfaction.
• Radiographic analysis including EBRA-FCA for subsidence and assessment for stress shielding and loosening.

Main Results:

• Significant improvement in clinical parameters persisted at 7-year follow-up (n=139).
• Mean subsidence of -1.44 mm was observed, followed by stabilization, with no signs of stress shielding.
• Cumulative revision rate was 2.23%, with early revisions for stem migration occurring in 0.89% of cases.

Conclusions:

• Calcar-guided short stems exhibit initial subsidence that stabilizes, rarely leading to revision.
• The absence of radiographic signs of stress shielding supports the benefits of metaphyseal anchoring.
• Demographic factors did not significantly influence the migration pattern.