Alignment in TKA: what has been clear is not anymore!

Excerpt

The optimal implant orientation when performing a total knee arthroplasty (TKA) remains a timely, pertinent, and unanswered question. For many years, the alignment debate has filled journals and congresses, and monopolised discussions among knee surgeons all around the globe. In the development of TKA surgery, Michael Freeman introduced the concept of right-angled femoral and tibial bone cuts (mechanical alignment) and the idea of parallel and equal flexion and extension spaces. Using the mechanical alignment target, the knee surgeon strived to create a neutral lower limb alignment represented by a hip-knee-ankle angle target of 180° ± 3° [4, 12]. Although the mean hip-knee-ankle angle (HKA) of patients scheduled for TKA is near neutral, there is a wide variation and only 0.1% have neutral femoral and tibial mechanical axes [1]. With a systematic approach, mechanical alignment introduces anatomic modifications for many individuals and results in unequal medial–lateral or flexion–extension bone resections. Multiple ligament release techniques and algorithms have been proposed to re-balance the unbalanced gaps created. …