Kinematic alignment is a possible alternative to mechanical alignment in total knee arthroplasty

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Medical device technology

Background:

• Total knee arthroplasty (TKA) aims to restore function and alleviate pain in patients with knee osteoarthritis.
• Traditionally, mechanical alignment (MA) has been the standard surgical technique for TKA.
• Kinematic alignment (KA), a newer technique, focuses on replicating the patient's native joint line orientation.

Purpose of the Study:

• To systematically review and compare the clinical and radiological outcomes of kinematically aligned (KA) TKA versus mechanically aligned (MA) TKA.
• To analyze differences in limb, knee, and component alignment between KA and MA TKA.
• To evaluate changes in joint line orientation angle (JLOA) from the native knee in KA TKA compared to MA TKA.

Main Methods:

• A systematic review of nine full-text articles in English was conducted.
• Five studies included a control group undergoing MA TKA.
• Data extracted included patient demographics, clinical scores, and radiological outcomes. Study levels ranged from I to IV.

Main Results:

• KA TKA demonstrated comparable or superior clinical outcomes to MA TKA at minimum 2-year follow-up.
• Limb and knee alignment were similar between KA and MA TKA; component alignment showed slight variations (tibial varus, femoral valgus).
• KA TKA achieved a JLOA more parallel to the floor, resembling the native knee, unlike the oblique JLOA in MA TKA. Implant survivorship and complication rates were similar.

Conclusions:

• Kinematic alignment in TKA yields similar or improved clinical outcomes compared to mechanical alignment at early follow-up.
• KA TKA effectively restores knee function without increased failure rates up to midterm follow-up.
• KA TKA's JLOA more closely replicates the native knee's orientation compared to MA TKA, offering an acceptable alternative alignment strategy.