Abstract
Introduction
The advantages of UKA include bone stock preservation, physiologic kinematics, retention of main knee ligaments, improved proprioception, & better functional outcome. A semi-active robotic system using CT-based data combined with intraoperative registration & tactile feedback has the potential for more precise implant placement & alignment. This purpose of this study was to compare robotic-assisted implantation (RAI) with conventional manual implantation (CMI) & to investigate whether this technology could lead to more reliable & reproducible outcomes.
Methods
We prospectively collected data on 32 RAI UKR and 30 CMI UKR. Baseline data collection included: age, gender, BMI, comorbidities, diagnosis, & pre-operative SF-12 Physical Component, SF-12 Mental Component, WOMAC pain, WOMAC Stiffness, & WOMAC Physical Functional scores. Postoperatively, SF-12 & WOMAC scores were recorded, in addition to routine arthroplasty follow-up.
Results
Preoperative characteristics were similar. At mean follow-up of 3.20 years (range 2 – 6.2 years), no significant differences were found on SF-12 Physical Component, SF-12 Mental Component, WOMAC pain, & WOMAC Physical Functional scores. Multivariate analysis demonstrated higher WOMAC stiffness scores (p=0.049) in the RA-UKR group.
There was no component loosening, progression of the arthritis in the remaining compartments, infection, or PE wear in either group. Revision of UKA to TKA was performed in 1 RAI patient due to persistent medial pain. One technology failure occurred. Additionally, there was a significant increase in operative time in the RAI group (average 20.4 min; p < 0.01) and in OR turnover time (average 32%; p =0.022).
Conclusion
No significant differences were found in function, pain, or mental well being at mid-term follow-up of patients that underwent either robotic assisted or conventional UKR. As has been found in other studies, there was improved mechanical alignment & component positioning radiographically but there were no significant differences in functional outcomes. Patient satisfaction is high & there is there is reduced patient cost when the procedure is performed conventionally. Robotic assisted procedures have been discontinued due to lack of clear advantages. We will continue to follow these patients to determine whether better clinical outcomes &/or increased implant longevity occurs over time.
