Abstract
Introduction
A careful evaluation of new technologies such as robotic-arm assisted total knee arthroplasty (RATKA) is important to understand the reduction in variability among users. While there is data reviewing the use of RATKA, the data is typically presented for experienced TKA surgeons. Therefore, the purpose of this cadaveric study was to compare the variability for several surgical factors between RATKA and manual TKA (MTKA) for surgeons undergoing orthopaedic fellowship training.
Methods
Two operating surgeons undergoing orthopaedic fellowship training, each prepared six cadaveric legs for cruciate retaining TKA, with MTKA on one side (3 knees) and RATKA on the other (3 knees). These surgeons were instructed to execute a full RATKA or MTKA procedure through trialing and achieve a balanced knee. The number of recuts and final poly thickness was intra-operatively recorded. After completion of bone cuts, the operating surgeons were asked if they would perform a cementless knee based on their perception of final bone cut quality as well as rank the amount of mental effort exerted for required surgical tasks. Two additional fellowship trained orthopaedic assessment surgeons, blinded to the method of preparation, each post-operatively graded the resultant bone cuts of the tibia and femur according to the perceived percentage of cut planarity (grade 1, <25%; grade 2, 25–50%; grade 3, 51–75%; and grade 4, >76%). The grade for medial and lateral tibial bone cuts was averaged and a Wilcoxon signed rank test was used for statistical comparisons. Assessment surgeons also determined whether the knee was balanced in flexion and extension. A balanced knee was defined as relatively equal medial and lateral gaps under relatively equal applied load.
Results
Operating surgeons used 9mm polys in all 6 RATKA specimens, and 3/6 MTKA specimens. Operating surgeons said they would do cementless in 4/6 RATKA specimens, and 1/6 MTKA specimen. In MTKA specimens, 5/6 cases had a recut on the tibia or femur to obtain knee balance. With RATKA, 1/6 cases had a recut on the tibia. With RATKA, operating surgeons performed a pre-resection balancing workflow, and made plan adjustments prior to resection. The operating surgeons reported reduced mental effort when performing bone measurements, tibial bone cutting, knee balancing, trialing, and post-resection adjustments with RATKA compared to MTKA. Mental effort was equivalent during femoral bone cutting between the two procedures and increased for RATKA during initial exposure and retractor setup.
Assessment surgeons considered all 6 RATKA and 2/6 MTKA specimens to be balanced. Assessment surgeons assigned RATKA specimens a higher grade for perceived planarity (3.86 vs. 3.48, p=0.03) than MTKA specimens.
DISCUSSION
In this cadaveric study, RATKA resulted in a higher usage of minimum poly thickness, greater tendency to want to use cementless components, higher number of balanced knees, higher perceived planarity, lower number of recuts, and reduced mental effort than MTKA cases. RATKA may give users more confidence in performing cementless TKA, especially for novice surgeons. Robotic-arm assisted TKA may allow for reduced surgical variability, which may improve patient outcomes, and should be investigated in a clinical setting.
