Is there a gold standard for TKA tibial component rotational alignment?

Area of Science:

• Orthopedic surgery
• Biomechanics
• Biomedical engineering

Background:

• Component alignment is crucial for joint function after total knee arthroplasty (TKA).
• The transepicondylar axis is standard for femoral component rotation, but tibial component rotational alignment varies.
• The effect of this variability on knee kinematics and stability remains unclear.

Purpose of the Study:

• To investigate how aligning the tibial component to four different axes affects knee stability and passive tibiofemoral kinematics post-TKA.
• To quantify changes in joint motion and stability based on tibial component rotational alignment techniques.

Main Methods:

• Utilized a custom surgical navigation system and a stability device to measure knee stability and passive motion.
• Tested 10 cadaveric knees, assessing them in their native state and after TKA with the tibial component aligned to four distinct axes.
• Employed a modified tibial tray for component alignment.

Main Results:

• No significant differences in knee stability or passive kinematics were observed among the four tibial rotational alignment techniques.
• Total knee arthroplasty (TKA) resulted in a 'looser' knee compared to the native state, characterized by increased laxity and anterior femoral translation.
• TKA also decreased mean maximum stiffness and increased internal-external tibial rotation during passive flexion, but these changes were not significantly different between alignment groups.

Conclusions:

• Total knee arthroplasty (TKA) inherently increases knee laxity, decreases stiffness, and alters tibiofemoral motion during passive flexion.
• The specific rotational alignment axis chosen for the tibial component in TKA has minimal impact on these overall changes.
• Surgeons can expect consistent outcomes regardless of the specific tibial alignment axis used from the examined techniques.