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Which method for femoral component sizing when performing kinematic alignment TKA? An in silico study
Fasen Huang1, Simon Harris2, Tianyu Zhou2
1MSK laboratory, Department of Surgery and Cancer, Imperial College London, London W12 0BZ, United Kingdom; Shenzhen Traditional Chinese Medicine Hospital, Shenzhen 518033, China.
The groove height method (ATG-KATKA) and medial facet height method (ATM-KATKA) for sizing femoral components in kinematically alignment total knee arthroplasty (KA-TKA) better restore native knee anatomy than the conventional method. However, these techniques increase implant overhang, particularly postero-laterally.
Area of Science:
- Orthopedic surgery
- Biomechanical engineering
- Medical imaging
Background:
- Kinematically alignment (KA) total knee arthroplasty (TKA) aims to replicate pre-arthritic knee anatomy.
- Accurate restoration of the native trochlear anatomy is crucial for optimal TKA outcomes.
- Identifying the best femoral component sizing technique in KA-TKA is essential for anatomical restoration.
Purpose of the Study:
- To compare three femoral component sizing techniques in KA-TKA.
- To determine which anatomical landmark best restores native trochlear anatomy.
- To evaluate the accuracy of femoral component sizing in relation to native knee geometry.
Main Methods:
- An in silico study utilizing 3D knee models.
- Virtual kinematically alignment of femoral components using GMK sphere® models.
- Comparison of three sizing techniques: conventional (C-KATKA), medial facet height (ATM-KATKA), and groove height (ATG-KATKA).
- Analysis of trochlear articular surface restoration and mediolateral implant overhang using in-house software.
Main Results:
- Alternative techniques (ATG-KATKA and ATM-KATKA) resulted in a mean increase in component size compared to C-KATKA.
- The conventional C-KATKA technique significantly understuffed the trochlear groove and facets.
- ATG-KATKA and ATM-KATKA techniques showed no significant understuffing of the groove or lateral facet.
- Both ATM-KATKA and ATG-KATKA techniques generated significant postero-lateral implant overhangs (86.7%–90.0%).
Conclusions:
- Conventional femoral component sizing in KA-TKA leads to substantial understuffing of the native trochlear anatomy.
- Personalized sizing techniques (ATM-KATKA, ATG-KATKA) improve anatomical restoration but increase implant overhang.
- The clinical significance of postero-lateral overhang requires further investigation.
- Optimization of femoral implant aspect ratio may enhance anatomical restoration in the anterior femoral compartment.
