Does the tibia component design affect the need for offset stems in revision total knee arthroplasty?

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiographic Analysis

Background:

• Stem/keel placement differs between anatomic and symmetric revision tibial baseplates.
• Understanding this variation is crucial for optimizing revision total knee arthroplasty (TKA).

Purpose of the Study:

• To investigate how stem location (anatomic vs. symmetric) affects the need for offset couplers in revision TKA.
• To quantify the offset required for different tibial baseplate designs based on bone defect size.

Main Methods:

• Digital templating of 75 patients' hip-to-ankle and lateral radiographs.
• Measurement of anterior-posterior and medial-lateral offset between tibial diaphysis center and baseplate stem.
• Analysis across four tibial resection levels relative to the fibular head.

Main Results:

• Anatomic baseplates required significantly less offset (2.28 mm vs. 5.44 mm) at resection levels up to the fibular head (p < 0.001).
• Symmetric baseplates required less offset at resection levels below the fibular head (e.g., 1.52 mm vs. 5.66 mm at level 3, p < 0.001).

Conclusions:

• Anatomic tibial baseplates offer advantages in revision TKA with minimal bone loss.
• Symmetric tibial baseplates are associated with reduced offset needs when significant bone defects are present.