CLINICAL IMPACT AND PREVALENCE FINDINGS

The prevailing consensus in total knee arthroplasty (TKA) is that tibia-femoral alignment should be within 3° of the leg’s neutral mechanical axis³⁴, a clinical outcome that is theoretically within the surgeon’s complete control. Despite this clinical standard, implant malalignment (frequently defined as a deviation of > ±3° from the mechanical axis) is a major cause of TKA implant failure, accounting for approximately 16% of total knee revisions.³⁵

A recent meta-analysis of twenty-nine clinical studies comparing large console computer-assisted surgery (CAS) to conventional instrument TKA found that 31.8% of TKAs performed with conventional instrumentation resulted in implant malalignment, compared to 9% of TKAs performed with CAS.³⁶ Given that 97% of TKAs performed in the U.S. today are performed using conventional instrumentation,³⁷ this 31.8% malalignment rate for conventional instrument TKA is a cause for concern. Since TKA clinical studies tend to be performed by high-volume TKA-specialist surgeons, this malalignment rate may actually be higher when taking into account TKAs performed by general orthopedic surgeons, which perform about 80% of all TKAs in the U.S.³⁸