Arthroplasty of the Knee: Current Techniques for Implant Alignment

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Medical device technology

Background:

• Traditional total knee arthroplasty (TKA) mechanical alignment creates a straight leg, regardless of pre-operative alignment, leading to dissatisfaction in 15-20% of patients.
• Mechanical alignment techniques include ligament balancing and bony referencing, with both yielding comparable 25-year survival rates around 80%.

Purpose of the Study:

• To introduce and evaluate the kinematic TKA alignment concept, designed to personalize implantation based on individual patient anatomy.
• To assess if kinematic alignment improves TKA function and achieves comparable long-term outcomes to traditional methods.

Main Methods:

• Comparison of traditional mechanical alignment (ligament balancing and bony referencing) with the newer kinematic alignment technique for TKA.
• Evaluation of implant positioning, ligament tension, and bony landmarks in mechanical alignment.
• Focus on reconstructing pre-arthritic anatomy, preserving the joint line, and maintaining the mechanical axis in kinematic alignment without ligamentous release.

Main Results:

• Kinematic TKA alignment aims to reconstruct patient-specific anatomy, potentially enhancing function.
• Initial studies indicate that TKA using kinematic alignment has comparable 10-year survival rates to traditional mechanical alignment.
• Both traditional and kinematic alignment techniques demonstrate comparable long-term survival rates.

Conclusions:

• Kinematic TKA alignment offers a personalized approach, potentially improving patient satisfaction and function.
• While kinematic alignment shows promise with comparable survival rates, long-term data is still limited.
• Further research is needed to determine the limitations of kinematic alignment and identify patient subgroups that benefit most.