To increase stability of the knee in a total knee arthroplasty, the prosthetic knee should be aligned relative to the TKA line in which position?

To increase stability of the knee in a total knee arthroplasty, the prosthetic knee should be aligned relative to the TKA line in which position?

• A. Anterior to the TKA line
• B. Medial to the TKA line
• C. Posterior to the TKA line
• D. Coinciding with the TKA line

Answer: (C)

Stability after a total knee replacement depends on how the implant sits relative to a reference line used for alignment. Positioning the prosthetic knee posterior to the TKA line creates a posterior offset that increases resistance to anterior tibial translation as the knee flexes. This helps the joint stay stable through the range of motion by reducing the tendency for the tibia to slide forward under load. If the component sits anterior to the line, the knee becomes more prone to instability in flexion due to less resistance to forward movement. Aligning exactly with the line offers neither the posterior offset nor the added resistance to anterior translation. Therefore, placing the prosthesis posterior to the TKA line best enhances stability.

Stability after a total knee replacement depends on how the implant sits relative to a reference line used for alignment. Positioning the prosthetic knee posterior to the TKA line creates a posterior offset that increases resistance to anterior tibial translation as the knee flexes. This helps the joint stay stable through the range of motion by reducing the tendency for the tibia to slide forward under load. If the component sits anterior to the line, the knee becomes more prone to instability in flexion due to less resistance to forward movement. Aligning exactly with the line offers neither the posterior offset nor the added resistance to anterior translation. Therefore, placing the prosthesis posterior to the TKA line best enhances stability.