Image-based robotic-assisted conversion from partial to total knee arthroplasty under functional alignment:...

Area of Science:

• Orthopedic Surgery
• Robotics in Medicine
• Arthroplasty

Background:

• Image-based robotic systems enhance precision in total knee arthroplasty (TKA) through patient-specific planning.
• Functional alignment (FA) utilizes the native soft tissue envelope for implant placement, but its use in partial TKA conversion is limited.
• This study investigates robotic-assisted partial-to-TKA conversion using FA principles.

Purpose of the Study:

• To evaluate the outcomes of image-based robotic-assisted partial-to-TKA conversion under FA principles.
• To compare these outcomes with a cohort of primary robotic TKAs.
• To assess the necessity of stems, augments, or constrained implants in these conversions.

Main Methods:

• Retrospective analysis of eight partial-to-TKA conversions using an image-based robotic system with a minimum 12-month follow-up.
• Comparison with a control group of 50 primary robotic TKAs.
• Assessment of demographics, implant constraints, intraoperative positioning, and postoperative outcomes.

Main Results:

• The primary reasons for revision were osteoarthritis progression (75%) and aseptic loosening (25%).
• No stems were required, and only one patient (12.5%) needed a tibial augment.
• Postoperative alignment and functional outcomes (Knee Society Scores, Forgotten Joint Score) were comparable to primary TKAs, with no complications or revisions.

Conclusions:

• Robotic-assisted partial-to-TKA conversion utilizing FA principles achieves functional and positioning outcomes similar to primary robotic TKA.
• This technique reduces the need for stems, augments, and constrained implants.
• Larger cohort studies are recommended to validate these findings.