Patient-Specific Flanged Acetabular Component Failure Is Associated With Excess Lateral Position Relative to Planned...

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Implant Design and Placement

Background:

• Complex acetabular revisions often utilize patient-specific custom flanged acetabular components (CFACs).
• Despite custom design for precision, achieving accurate CFAC placement remains a surgical challenge.
• The impact of CFAC placement accuracy on aseptic loosening and long-term survivorship is not well-established.

Purpose of the Study:

• To evaluate the accuracy of CFAC placement compared to pre-operative planning and the native anatomic hip center (AHC).
• To determine if placement accuracy is associated with radiographic failure or the need for re-revision surgery.

Main Methods:

• A retrospective review of 99 CFAC procedures in 94 patients (2004-2017) was conducted.
• Postoperative radiographs were analyzed to measure deviations from planned position and distance from the AHC.
• Aseptic failure was defined by radiographic loosening or re-revision due to aseptic loosening.

Main Results:

• Over 60% of CFACs were placed more than 5 mm from the planned position, with a mean deviation of 7.1 mm.
• Implants revised for aseptic loosening showed significantly more lateral placement (5.7 mm) compared to maintained implants (3.0 mm).
• Excessive proximal placement relative to the AHC was associated with implant failure (13.0 mm vs. 7.3 mm).

Conclusions:

• Patient-specific CFAC placement frequently deviates from the planned position.
• Excessive lateral deviation from the planned position is linked to increased re-revision rates.
• Accurate placement, especially in the craniocaudal axis relative to the AHC, is critical for successful CFAC outcomes.