Robotic Total Knee Arthroplasty is Associated with Thinner and Less Constrained Polyethylene Inserts

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Robotics in Medicine

Background:

• Accurate gap assessment in total knee arthroplasty (TKA) is crucial for optimal implant selection.
• Thicker or more constrained polyethylene inserts may be necessitated by suboptimal gap balancing.
• Robotic assistance offers potential for improved pre-resection planning and execution.

Purpose of the Study:

• To evaluate if robotic assistance in TKA leads to the selection of thinner and less-constrained polyethylene inserts.
• To compare implant characteristics between robotic-assisted TKA (RA-TKA) and conventional manual TKA (CM-TKA).

Main Methods:

• Retrospective review of 408 primary TKA cases.
• Comparison of two cohorts: CM-TKA (169 knees) and RA-TKA (237 knees).
• Analysis of operative notes for polyethylene insert thickness, constraint level, and use of robotic assistance.

Main Results:

• RA-TKA group used thinner polyethylene inserts (mean 11.0mm vs. 11.7mm, p<0.0001).
• Higher utilization of the thinnest 10mm insert in RA-TKA (43% vs. 34%, p=0.048).
• Significantly lower rates of "outlier" (≥14mm) and constrained insert use in RA-TKA (5% vs. 18% and 4% vs. 18%, respectively, p<0.0001).

Conclusions:

• Robotic assistance in TKA facilitates the use of thinner polyethylene inserts.
• RA-TKA reduces the need for "outlier" and constrained polyethylene insert sizes compared to conventional methods.
• This suggests robotic assistance may improve implant selection and potentially joint balancing in TKA.