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Inverse kinematic alignment outperforms adjusted mechanical alignment in varus TKA at 5 years
Philip Winnock de Grave1, Oscar Roosens1,2, Hannes Vermue1,3
1Department of Orthopaedic Surgery, AZ Delta, Roeselare, Belgium.
Summary
Inverse kinematic alignment (iKA) in robotic-assisted total knee arthroplasty (TKA) shows better 5-year functional outcomes for varus knees compared to adjusted mechanical alignment (aMA). iKA better preserves native knee anatomy, leading to improved patient scores.
Area of Science:
- Orthopedic Surgery
- Biomechanical Engineering
- Robotic Surgery
Background:
- Varus knee alignment presents unique challenges in total knee arthroplasty (TKA).
- Patient-specific alignment may offer advantages over traditional methods in these cases.
- Robotic-assisted TKA allows for precise execution of alignment strategies.
Purpose of the Study:
- To compare 5-year functional outcomes of robotic-assisted TKA using inverse kinematic alignment (iKA) versus adjusted mechanical alignment (aMA).
- To specifically evaluate outcomes in patients with preoperative varus knee alignment.
- To assess the impact of alignment strategy on native knee anatomy preservation.
Main Methods:
- Retrospective matched cohort analysis of 90 patients (45 iKA, 45 aMA) with preoperative varus alignment undergoing robotic-assisted TKA.
- Patients were matched based on demographics, preoperative alignment, osteoarthritis severity, and baseline scores (OKS, EQ-5D).
- Functional outcomes (Oxford Knee Score, Forgotten Joint Score, Metabolic Equivalent of Task) and radiographic parameters were assessed at 5 years.
Main Results:
- The iKA group demonstrated significantly higher 5-year functional outcomes, including Oxford Knee Score (OKS) and Forgotten Joint Score (FJS).
- Metabolic Equivalent of Task (MET) scores were also significantly higher in the iKA group.
- Radiographically, iKA resulted in a higher postoperative medial proximal tibial angle (MPTA) and smaller distal medial femoral resections, indicating better preservation of native tibial and femoral anatomy.
Conclusions:
- Inverse kinematic alignment (iKA) provides superior 5-year functional outcomes for patients with varus knee alignment undergoing robotic-assisted TKA compared to adjusted mechanical alignment (aMA).
- iKA is associated with better preservation of native tibial and medial femoral anatomy.
- These findings support the use of iKA for optimizing TKA outcomes in varus knees.
