Mechanical Alignment in Knee Replacement Homogenizes Postoperative Coronal Hip-Knee-Ankle Angle in Varus Knees: A...

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Medical Imaging

Background:

• Postoperative lower limb alignment after knee replacement is crucial for functional outcomes.
• The hip-knee-ankle (HKA) angle is a key indicator of coronal alignment.
• Preoperative dynamic alignment patterns can influence surgical outcomes.

Purpose of the Study:

• To determine the dynamic coronal hip-knee-ankle (HKA) angle after mechanical alignment in total knee replacement using computer navigation.
• To assess the impact of computer navigation on achieving optimal HKA alignment across different knee flexion angles.

Main Methods:

• A pre-post design study involving 71 patients undergoing total knee arthroplasty for varus osteoarthritic knees.
• Hip-knee-ankle (HKA) angle measurement using a navigation system at 30, 60, and 90 degrees of knee flexion, before and after surgery.
• Assessment of implant position and flexion/extension gaps postoperatively.

Main Results:

• Statistically significant differences (p < 0.0001) were observed in dynamic coronal HKA between preoperative and postoperative statuses.
• Postoperatively, 98.6% of knees achieved HKA within ±3 degrees at full extension.
• 80.6% of knees demonstrated "within-range" dynamic alignment at all measured flexion angles (30, 60, 90 degrees).

Conclusions:

• Mechanically aligned total knee replacement using computer navigation significantly improves dynamic coronal HKA.
• Excellent dynamic HKA alignment is achieved not only at full extension but also maintained across various flexion angles.
• Computer navigation facilitates precise alignment, crucial for optimizing patient outcomes after total knee arthroplasty.