Mako Total Knee

Robotic-Arm Assisted Surgery

Combines Mako Robotic-Arm Assisted Technology with the Triathlon Total Knee System. The outcomes you can achieve with the Mako Total Knee application have the potential to create the future of your orthopaedic service line.

Total knee arthroplasty (TKA) has demonstrated clinical success,1,2 however data shows mechanical axis malalignment of greater than 3° in 9.0% of computer-assisted and 31.8% of conventional TKA surgeries3

Introducing Mako Total Knee, the newest application for the Mako System. In a cadaveric study, this application demonstrated the potential to increase the accuracy of TKA bone cuts and component placement to plan, even for an experienced user of manual instrumentation who is new to robotic technology. On average, Mako Total Knee final bone cuts and final component positions were 5.0 and 3.1 times more precise to plan than the manual total knee arthroplasty control, respectively.4

Mako Total Knee demonstrated soft tissue protection, including no ligament disruption to the PCL, MCL, LCL, and patella ligament, and did not require tibial subluxation or patella eversion for visualization during cutting, in a cadaveric study.5
 
Our U.S. market-leading Triathlon Total Knee System has demonstrated 99% survivorship in a ten-year study6, with over 2 million implanted worldwide.7

Related categories

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.

Comparison of RATKA and MTKA mean cuts and implant position to plan for all 6 matched pairs (n=6) and last 3 matched pairs (n=3). For final bone cut to plan, on the femur, A=Anterior, AC=Anterior Chamfer, D=Distal, PC=Posterior Chamfer, and P=Posterior, and on the tibia, T=Tibia. For final component position to plan, F-I=Femoral Implant, T-I=Tibial Implant. V/V=varus or valgus, F/E=flexion or extension, I/E=internal or external, andA/P=anterior or posterior slope. Error bars represent standard deviation. *Indicates a significant difference between RATKA and MTKA for n=6, with RATKA having less variance.

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.

A) Manually performed TKA with arrow pointing to PCL, with no bone island preparation.

B) Robotically performed TKA, with bone island preparation in front of PCL and corresponding tibial view from Implant Planning page (showing implant plan to the actual boney anatomy, with remaining bone island). Black arrow points to PCL. White arrows outline bone island.