Dr. João Paulo Sousa

Orthopedic Surgeon
Orthopedics Group
Coordinator

Digital ligament tensor in robotic surgery for knee arthrosis.
The excellence of innovation

HPA Magazine 23 // 2025

The Digital Tensor that we have started using in robotic knee replacement surgery – commonly known as knee replacement – is an innovative solution, pioneered in Europe, that allows the surgeon to quantify joint laxity before performing the bone resections required for the placement of the implant.
By having access to this information in a quantifiable and rigorous way, the surgeon is able to plan and execute the procedures necessary to tension the ligaments that will provide the greatest possible stability to the joint.

Knee arthroplasty, also known as total knee replacement (TKP), has been one of the focuses of the greatest specialization and technical and scientific investment of the Orthopedics Group at HPA (GO HPA) since the beginning.
In 2011, we were pioneers and the first national users of the PSI (Patient -Specific Instrumentation) system, a system in which a specific cutting block is produced for each patient that adapts to their femur and tibia, the result of planning that seeks to choose the size and position that best suits their anatomy, with the aim of optimizing function and clinical outcome. Since then, it has become the standard procedure, reserving conventional instrumentation (CI), which is used in the vast majority of national services, for patients in whom PSI was not possible or indicated.
From April 2023, we started surgery with robotic instrumentation (IR), having been pioneers of this technique in Portugal.
This technique takes into account not only the bone morphology (also offered by PSI) but also the entire muscle-ligament envelope, trying to position the implant in the best way for each patient, and the current case series already exceeds one hundred patients.
From January 2025, we were the first in Europe to use a digital ligament tensioner, improving this technique in precision, accuracy, and safety, which we believe will also increase levels of functionality and patient satisfaction.
This technology replaces what was previously done manually, offering an objective and consistent measurement of the tension to be applied, i.e., allowing the knee ligaments to be positioned in a personalized way at their ideal tension.
This guide is used intraoperatively and allows the joint to be tested throughout the range of motion, from maximum extension to maximum flexion, predicting the natural balance of the ligaments and the total kinematic stability of the knee.