Hip replacement: virtual surgical training with haptic technology

Surgeons have only limited options to practice surgical techniques before they enter the operating room. The implantation of an endoprosthesis requires extensive practical training since it necessitates strength and utmost precision. The "Dynamic HIPS" project develops a virtual reality hip implant simulator that provides realistic haptic feedback.

In this MEDICA-tradefair.com interview, Dr. Mario Lorenz talks about the development of the virtual reality (VR) simulator that allows surgeons to practice hip replacement procedures.

Dr. Lorenz, what is the objective of the "Dynamic HIPS" project?

Dr. Mario Lorenz: We are developing a training simulator for hip replacement surgeries. Not only does the user operate in a VR setting, but the simulator will also provide haptic feedback, allowing the surgeon to feel the realistic forces at play during the surgery.

The device targets doctors in specialty training to become orthopedic or trauma surgeons. The simulator enables them to practice the surgical procedure in a virtual setting before they perform their first real-life surgery under supervision – all without the need for human body donations or animals. The simulator is not intended as a replacement but is meant to be complementary to conserve resources in surgical training.

The simulator is called "dynamic". What does that mean?

Lorenz: We only simulated one part of the surgery in the predecessor project, namely the acetabular reaming process. The new simulator also addresses the other steps of the surgery, especially the technique of hammering the prosthetic parts into the bone. This is a highly dynamic process with high impact forces. Simulating this movement is our biggest challenge.

The project focuses on hip replacements. However, given the corresponding adaptation, the technology could also be applied to simulate other joint replacement surgeries.

What is the simulator scenario?

Lorenz: It pertains to primary hip replacement surgery, not revision surgery. It means the incision at the hip and closing of the surgical wound are not part of this process, but it incorporates all steps related to the bone and joint. This includes the dislocation of the joint and the removal of the femoral head from its socket, the acetabular reaming, the hammering of prosthetic parts into the artificial socket, and the placement of the acetabular insert/liner inside the acetabular cup.

On the upper part of the thigh bone, the bone marrow is aspired from the femur and the surgical rasps of various sizes are mounted in to make room for the stem that is inserted into the femur. Then the final shaft is inserted, possibly with a temporary component to check and adjust the movement and position of the implant prosthetic. The final ball is subsequently inserted into the new socket, assuring proper sizing and positioning of the new joint.

How do you create realistic haptic feedback?

Lorenz: In the project predecessor, we already conducted biomechanical testing to measure the interactional forces and torques during acetabular reaming. For the surgery’s next steps, we also plan to make femoral measurements starting in October. We will team up with our partner, the Division of Macroscopic and Clinical Anatomy at the Medical University of Graz (Austria) for this process. We will subsequently review the results with the help of experienced surgeons.

The project has been running for almost eleven months. What are the interim results?

Lorenz: We have already laid the groundwork for various subareas. There is a rough training and process concept, early details for error feedback we like to provide, and the basic synchronization of a multi-user mode that facilitates a location-independent connection and allows participants to share the VR environment. We have also completed the planning process for the outstanding biomechanical measurements. The bulk of the work will take place over the next twelve months, during which we plan to finish developing and connecting all areas. A prototype is expected to be available in a year to be evaluated by surgeons.