Dr. João Paulo Sousa

Orthopedic Surgeon
Orthopedics Group
Coordinator

Robotic surgery for knee arthrosis:
Optimizing technology, strengthening satisfaction

HPA Magazine 22 // 2024

Knee arthroplasty, commonly known as total knee replacement (TKR), has been one of the main areas of specialization and technical and scientific investment since the establishment of the Orthopedics Group at HPA (GO HPA).
In 2011, we were pioneers and the first national users of the PSI (Patient-Specific Instrumentation) system, which involves producing a specific cutting block for each patient to adapt to their femur and tibia.
This planning aims to select the size and position that best suits the patient's anatomy to optimize function and clinical outcomes. Since then, PSI has become the standard procedure, with conventional instrumentation (CI) reserved for patients for whom PSI is not feasible or indicated.

Knee arthroplasty, commonly known as total knee replacement (TKR), has been one of the main areas of specialization and technical and scientific investment since the establishment of the Orthopedics Group at HPA (GO HPA).
In 2011, we were pioneers and the first national users of the PSI (Patient-Specific Instrumentation) system, which involves producing a specific cutting block for each patient to adapt to their femur and tibia.
This planning aims to select the size and position that best suits the patient's anatomy to optimize function and clinical outcomes. Since then, PSI has become the standard procedure, with conventional instrumentation (CI) reserved for patients for whom PSI is not feasible or indicated.
A year ago, in April 2023, we performed the first surgery using robotic instrumentation (RI) in Portugal.
The robot assists in selecting the position and size of the implant that best fits each knee, considering not only bone morphology (already provided by PSI) but also the entire ligament muscle envelope to place the implant in a way that suits each patient.
This advancement aims to reduce the level of patient dissatisfaction following knee arthroplasty, which is relatively higher than that observed in hip prostheses. In conclusion, achieving patient satisfaction after hip arthroplasty is much easier than after knee arthroplasty.
The rate of dissatisfaction after a TKR, in internationally published literature, is around 15 to 20%. This doesn't mean that patients are worse off than before the surgery; most of them aren't, but they don't meet their expectations.
We now have a case series for a preliminary assessment of the use of surgery with RI (51 cases) compared to CI and PSI (277 and 499 cases, respectively).
We surveyed operated patients and asked them to rate their satisfaction on a scale from one to ten, with one being “completely dissatisfied” and ten being “completely satisfied”.
We categorized responses as “dissatisfied” for values between one and five, “satisfied” for values between six and eight, and “very satisfied” for values nine and ten. We have the results of 827 cases, with the distribution of satisfaction levels as follows: 47% rated their satisfaction as ten, 18% as nine, 18% as eight, and 7% as below six. (Graphic 1)

Graphic 1 – Distribution of satisfaction after total knee arthroplasty
When we analysed satisfaction based on different techniques, we observed a 25% reduction in dissatisfied patients between CI and PSI (from 8% to 6%). It is important to note that with robotic surgery, we have a smaller evaluated series (51 cases compared to 277 CI and 499 PSI). However, we have not received ratings below 7 yet, resulting in zero dissatisfied patients so far. We anticipate that dissatisfied patients may emerge as the series progresses. Additionally, we noticed that the percentage of those who are "very satisfied" is lower compared to CI and PSI (63% versus 65% and 66%, respectively). (Graphic 2)

Graphic 2 – Distribution of satisfaction among the three types of instrumentation
Graphic 3 represents the average satisfaction by type of surgery, showing an increase of 0.23 in satisfaction in favour of robotic surgery compared to the PSI technique. This is a purely descriptive evaluation without statistical treatment or scientific rigor, and the robotic surgery series is still limited but shows very promising results with satisfaction levels close to those of hip arthroplasty. This leaves us very satisfied and motivated to continue on this path.
It is important to note that one of the main and most serious causes of dissatisfaction, the infection rate in our series (1020 knees operated with prosthesis), is less than 0.4%.
This rate is comparable to any centre worldwide and provides peace of mind to us and our patients, as the impact of a prosthesis infection is significant from clinical, social, and economic perspectives.
 
Graphic 3 – Average satisfaction values for the three types of instrumentation
From a scientific standpoint, the analysis of our data and the sharing of our experience have already resulted in more than a dozen articles published in indexed international journals and dozens of presentations at national and international conferences. All of this is the outcome of multidisciplinary teamwork in a "service" format, which aims to continuously analyse the results and conduct the activities of the GO HPA in a structured and systematic manner. The goal is to provide patients with the most favourable conditions so that their functional and quality of life outcomes are optimized.