Lateral Instability 13 Years After Kinematically Aligned Total Knee Arthroplasty

To reduce unsatisfied patients following total knee arthroplasty (TKA), kinematic alignment has been introduced as an alternative to mechanical alignment. Studies have shown no significant differences in functional outcomes and early revision rates between alignment strategies. This case report presents a 64-year-old patient who developed progressive varus alignment and lateral instability 13 years after a kinematically aligned TKA. The case highlights the impact of varus alignment on the risk of medial plastic wear and lateral soft tissue attenuation. Both can contribute to lateral instability, a lateral thrust, and progressive varus deformity in unrestricted kinematic alignment TKA. This article suggests that excessive varus alignment should be avoided and restricted alignment targets should be considered when using kinematic, or functional alignment in TKA for varus osteoarthritis.