Abstract
Introduction
While manual total knee arthroplasty (MTKA) procedures have demonstrated excellent clinical success, occasionally intraoperative damage to soft tissues can occur. Robotic-arm assisted technology is designed to constrain a sawblade in a haptic zone to help ensure that only the desired bone cuts are made. The objective of this cadaver study was to quantify the extent of soft tissue damage sustained during TKA through a robotic-arm assisted (RATKA) haptically guided approach and conventional MTKA approach.
Methods
Four surgeons each prepared six cadaveric legs for CR TKA: 3 MTKA and 3 RATKA, for a total of 12 RATKA and 12 MTKA knees. With the assistance of an arthroscope, two independent surgeons graded the damage of 14 knee structures: dMCL, sMCL, posterior oblique ligament (POL), semi-membranosus muscle tendon (SMT), gastrocnemius muscle medial head (GMM), PCL, ITB, lateral retinacular (LR), LCL, popliteus tendon, gastrocnemius muscle lateral head (GML), patellar ligament, quadriceps tendon (QT), and extensor mechanism (EM). Damage was defined as tissue fibers that were visibly torn, cut, frayed, or macerated. Percent damage was averaged between evaluators, and grades were assigned: Grade 1) complete soft tissue preservation to ≤5% damage; Grade 2) 6 to 25% damage; Grade 3) 26 to 75% damage; and Grade 4) 76 to 100% damage. A Wilcoxon Signed Rank Test was used for statistical comparisons. A p-value <0.05 was considered statistically significant.
Results
Significantly less damage occurred to the PCL in the RATKA than the MTKA specimens (p=0.004). RATKA specimens had less damage to the dMCL (p=0.186), ITB (p=0.5), popliteus (p=0.137), and patellar ligament (p=0.5). The sMCL, POL, SMT, GMM, GML, LR, LCL, QT, and EM were grade 1 in all MTKA and RATKA specimens. No intentional soft tissue releases were performed in either group to balance the knee.
Discussion/Conclusion
The results of this study indicate that RATKA may result in less soft-tissue damage than MTKA, especially to the posterior cruciate ligament. This finding can potentially be attributed to RATKA using a haptic boundary to constrain the sawblade, which can help prevent unwanted soft-tissue damage. However, since any damage was post-operatively assessed and in a cadaveric model, further investigations on soft-tissue damage from patients with clinical outcomes should be performed.
