Mako Total Knee

Robotic-arm assisted total knee arthroplasty demonstrated greater accuracy to plan compared to manual technique⁴

Materials and methods

• Sample Size: 6 cadaveric specimens (12 knees)
  prepared by single surgeon.
• RATKA performed on the right leg and MTKA  performed 
  on the left  leg.
• Fiducial clusters assembled to femoral and
  tibial bones.
• Pre-op CTs segmented to create 3D plans with TKA component positional targets relative to fiducial clusters.
• NDI Polaris optical tracking system and navigated probe were used to measure final bone cut and final component position relative to the fiducials.
• Implants modified to accept measurement probe.
• Means and standard deviations for each final measurement were compared between RATKA and MTKA for each planar bone cut and component position in the sagittal, coronal, and axial planes.
• Measurements were made as the absolute deviation from plan, where:

    • Accuracy = Mean Value of Measurements

    • Precision = Standard Deviation of Measurements

• Average RATKA/MTKA error ratio was calculated for final bone cut (FBC) and final component position (FCP) to plan to compare overall accuracy and precision between RATKA and MTKA.
• Statistical Analysis: Individual and Moving Range (I/MR) graphs were used to assess and compare the mean location of the two methods. Two-Variance assessment using Levene’stest was performed with alpha=0.05 to evaluate for significant differences between the precision of the two methods.

 Results

Accuracy

• Comparing the means for all six matched pairs (n=6), RATKA final bone cuts and final component positions were as or more accurate to plan than MTKA control, for 11/12 and 5/5 measurements, respectively, and all (17/17) measurements when comparing the last three matched pairs (n=3).
• On average, RATKA (n=6) final bone cuts and final component positions were 4.2 and 3.2 times more accurate to plan than the MTKA control, respectively.

Precision

• Comparing the standard deviations for all six matched pairs (n=6), RATKA final bone resections and final component positons were as or more precise to plan than the MTKA control on all femoral and tibial V/V measurements, and all measurements when comparing the last three matched pairs (n=3).
• On average, RATKA (n=6) final bone cuts and final component positions were 5.0 and 3.1 times more precise to plan than the MTKA control, respectively.

Significance

RATKA has the potential to increase the accuracy of TKA bonecuts and component placement to plan, even for an experienced user of manual instrumentation who is new to robotic technology.

Robotic-arm assisted total knee arthroplasty demonstrated soft tissue protection⁵

Methodology

• SampleSize: 14 cadaveric specimens prepared for Triathlon CR TKA using the Mako System by more than 5 surgeons with no prior clinical, robotic experience, compared to 7 specimens prepared using MTKA (manual TKA) by single surgeon.
• Presence of soft tissue disruption was assessed by having a surgeon perform visual evaluation and palpation of the PCL, MCL, LCL, and the patellar ligament after the procedures.
• Documented leg pose and retraction during bone resections - Recorded any tibial subluxation and/or patellar eversion.

Results

• RATKA (Robotic-arm assisted TKA) cases demonstrated several aspects of soft tissue protection, in this cadaveric study.