[Progress on femorotibial mechanical axis of total knee arthroplasty]

Femorotibial mechanical axis (FTMA) is one of important factors influencing clinical effect after total knee arthroplasty (TKA). It is generally believed that the range of lower limb alignment after TKA is controlled within neutral FTMA ± 3 °, which has more advantages in improving joint function, prolonging prosthesis survival rate and reducing revision rate, and obtain better clinical results. Therefore, neutral FTMA is also considered to be the gold standard for TKA. However, with the application of computer-assisted surgery and other technologies, the alignment of FTMA is more accurate than before, but the clinical effect after surgery has not significantly improved. Some scholars have begun to question the necessity of neutral alignment of FTMA, and proposed alignment methods such as kinematics and retained residual deformity, which could achieve better clinical effects. In recent years, it has been reported that FTMA might not be the most important factor influencing postoperative clinical effects, and it is suggested that the arrangement and measurement of lower limbs and the effects on adjacent joint functions could affect clinical effect after TKA. The paper reviews neutral FTMA alignment is still an important factor for success of TKA. After a thorough evaluation according to the patient's condition, it should be appropriately applied in the case of neutral FTMA alignment; the operator should explore other factors which affect clinical outcome after TKA, and improve it to achieve the best therapeutic effect.