Computer assisted orthopedic surgery; its influence on prosthesis size in total knee replacement

Area of Science:

• Orthopaedic Surgery
• Medical Device Technology
• Surgical Navigation Systems

Background:

• Computer Assisted Orthopaedic Surgery (CAOS) has improved component alignment in Total Knee Arthroplasty (TKA).
• The accuracy of CAOS in determining component size remains less understood.
• Accurate component sizing is crucial for successful TKA outcomes.

Purpose of the Study:

• To evaluate the accuracy of component sizing (femoral and tibial) using the Brainlab CAOS system in TKAs.
• To compare CAOS-guided sizing with pre-operative templating and post-operative assessments.
• To identify potential risks associated with CAOS in component selection.

Main Methods:

• A comparative study of 40 Total Knee Arthroplasties (TKAs), with 20 using CAOS and 20 using conventional methods.
• Evaluation of femoral and tibial component sizes against pre-operative templating.
• Post-operative scoring to assess the adequateness of component size.
• Statistical analysis using kappa values to determine agreement and t-tests for significant differences.

Main Results:

• Fair agreement was observed between templated and implanted component sizes for both femur (kappa=0.38) and tibia (kappa=0.35).
• The CAOS group showed significantly higher rates of femoral component oversizing (p=0.020).
• No significant difference in tibial component sizing was found between CAOS and conventional groups.

Conclusions:

• There is an elevated risk of femoral component oversizing when utilizing the Brainlab CAOS system with the NexGen TKA components.
• CAOS accuracy in component sizing requires further investigation to optimize TKA procedures.
• Surgeons should be cautious regarding femoral component selection when employing CAOS in TKA.