Abstract
Introduction
We report 10-year clinical outcomes of a prospective randomised controlled study on uni-compartmental knee arthroplasty using an active constraint robot.
Measuring the clinical impact of CAOS systems has generally been based around surrogate radiological measures with currently few long-term functional follow-up studies reported. We present 10 year clinical follow up results of robotic vs conventional surgery in UKA.
Material and methods
The initial study took place in 2004 and included 28 patients, 13 in the robotic arm and 15 in the conventional arm. All patients underwent medial compartment UKA using the ‘OXFORD’ mobile bearing knee system. Clinical outcome at 10 years was scored using the WOMAC scoring system.
Results
13 patients were initially included in the robotic arm, of these one was revised following trauma and a further two patient died leaving at total of 10 with an average age of 80 years. In the control arm, out of a total of 15 patients, 3 were revised to a total knee replacement due to pain, 1 has died and 1 lost to follow-up. Their mean age is 81.
A total of 19 patients were included (conventional n=9, robotic n=10) in this follow up study. The WOMAC scores for the robotic group were lower - (p<0.05).
Discussion
There is a paucity of data on 10 year outcome of computer assisted UKA and whilst most studies show no clinical benefit, our study suggests a better outcome, however our numbers now are small (n=19).
In our original study 1 the primary outcome measure, tibiofemoral alignment in the coronal plane was within 2 degrees of the planned position in the robotic group whilst in the conventional group only 6 of the 15 knees achieved this level of accuracy - Fig 1.
The primary hypothesis was that the use of an active constraint robot improved prosthetic position. This accuracy continues to be associated with improved functional outcome.
Three revisions were performed prior to this period and were considered technical failures and have been excluded from this analysis.
