Impact of Tibial Base Design and Anatomy on Coverage and Alignment in TKA

Overview

This study evaluated how tibial base design attributes and patient tibial morphology affect tibial coverage and rotational alignment after total knee arthroplasty (TKA). Using CT scans from 14,791 patients, the research demonstrated that increasing tibial base size options improves coverage across morphologies, while asymmetry in tibial base design benefits coverage primarily in patients with asymmetric tibiae.

Background

Optimizing tibial base rotational alignment and maximizing coverage are critical to the long-term success of TKA. Mal-rotation of the tibial base is linked to higher revision rates, yet the minimal coverage needed for fixation remains unclear. Variations in tibial plateau morphology complicate implant selection, as asymmetric tibiae may require different base designs or rotational strategies. Some advocate asymmetric tibial bases or rotating platform designs to better match native anatomy and improve outcomes.

Data Highlights

Lower limb CT scans from 14,791 patients with end-stage osteoarthritis were analyzed. The cohort had a mean height of 1.68 m, weight of 85 kg, and 62% were female. Tibial morphology metrics included medial and lateral plateau lengths, aspect ratios, and tibial skew. Four tibial base designs with varying size distributions and asymmetry were virtually implanted to assess coverage and alignment optimization.

Key Findings

• Increasing the number of tibial base sizes improved tibial coverage regardless of patient tibial morphology.
• Asymmetric tibial base designs improved coverage primarily in patients with asymmetric tibiae.
• Patients with longer medial plateaus tended to require internal rotation of the tibial base to optimize coverage.
• Symmetric tibial bases in patients with symmetric tibiae reduced the need for mal-rotation.
• Rotating platform tibial bases theoretically allow independent rotation of the insert, enabling maximal coverage without compromising knee mechanics.

Clinical Implications

Surgeons should consider patient-specific tibial morphology when selecting tibial base designs to optimize coverage and minimize mal-rotation. Utilizing tibial base systems with a greater number of sizes can enhance coverage across diverse anatomies. For patients with asymmetric tibiae, asymmetric base designs may reduce the need for rotational compromises, potentially improving implant longevity.

Conclusion

This large-scale analysis highlights the importance of matching tibial base design attributes to patient anatomy to optimize coverage and alignment in TKA. Tailoring implant selection based on tibial morphology can improve surgical outcomes and reduce revision risks.

References

1. Author/Source/Year -- Impact of Tibial Base Configuration and Patient Anatomy on Tibial Coverage and Rotational Alignment Post-Total Knee Arthroplasty