Femoral Component Rotation in Total Knee Arthroplasty Using a Tibia-First, Gap-Balancing, "Functional Alignment"...

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Imaging

Background:

• Total knee arthroplasty (TKA) aims to restore knee function and alignment.
• Component rotation is critical for optimal TKA outcomes.
• Current techniques for femoral component rotation vary, impacting results.

Purpose of the Study:

• To describe femoral component rotation in TKA using a novel tibia-first, gap-balancing, functional alignment technique.
• To evaluate the rotational alignment of the prosthetic components relative to native bone anatomy.
• To assess the clinical outcomes, specifically patellar tracking and patient-reported outcome measures (PROMs).

Main Methods:

• Computer navigation was used for TKA in 97 osteoarthritis patients.
• Tibial resection followed kinematic alignment (KA) principles.
• Femoral rotation was determined using a gap-balancing technique, with rotational axes (TEA, PCA, rPCA) measured via MRI and intraoperative data.

Main Results:

• The mean angles measured were PCA/TEA (-5.1° ± 2.1°), rPCA/TEA (-4.8° ± 2.6°), and rPCA/PCA (-0.4° ± 1.7°).
• Negative values indicated internal rotation of the prosthetic components.
• No lateral release was required, and no instances of patellar maltracking were observed postoperatively.

Conclusions:

• The tibia-first, gap-balancing functional alignment technique effectively integrates gap balancing with kinematic principles.
• This method accommodates tibial slope variations by resecting the tibia first.
• The resulting femoral rotation is internally rotated, similar to KA-TKA, and does not lead to patellar maltracking.