Mechanical alignment (MA) was introduced in 1973 by Michael Freeman, who proposed systematically performing the femoral and tibial bone cuts perpendicular to their mechanical axes. At the time, instrumentation and implants were rudimentary, and this “one size fits all” technique was a promising approach to simplify and standardize the procedure. Total knee arthroplasty (TKA) performed with MA has since been perceived as essential for TKA success and has established an excellent long-term survival rate of 82% at 25 years.
Interestingly, despite decades of implant design modifications and improved surgical precision with sophisticated robotic-assisted tools, patient function and satisfaction have completely plateaued. Data shows that 75% of patients do not experience a natural joint, 50% suffer from residual symptoms, and 25% would outright refuse to undergo the same surgery again. Applying a systematic, unyielding alignment technique to a highly variable human bony anatomy represents a fundamental flaw that leaves significant room for clinical improvement.
