Better joint prosthetics thanks to AI-based motion analysis
Joint prosthetics are continuously improving, thanks to follow-up studies of patients who have received new hip or knee joints. At Sahlgrenska University Hospital, patients’ movement patterns are analyzed both before and for an extended period after surgery. A grant of 1.4 million SEK from the Lundberg Research Foundation will go toward modern video technology and AI-based software, streamlining the work and improving the experience for patients.
In 2023, approximately 52,000 hip or knee replacement surgeries were performed in Sweden. Both joint prosthetics and treatments are advancing, largely driven by research that follows up with patients after surgery. Roy Tranberg, an associate professor of biomechanics at the Gait and Motion Laboratory at Sahlgrenska Academy, University of Gothenburg, meets around 250 patients with joint prosthetics each year as part of long-term studies.
Extensive follow-up
Some patients scheduled for prosthetic surgery are asked if they would like to participate in a study. Those who agree are randomly assigned a specific prosthetic type from several options. Even before their surgery, they come to the Gait and Motion Laboratory, where their movement patterns are studied and documented. After the operation, they return for further analysis.
“Our part is just one of several components in the study. Besides our assessment of how patients move, they are also X-rayed, fill out questionnaires, undergo examinations, and are followed up in various ways. This is repeated many times after the surgery, initially with only a few months between check-ups and later with longer intervals,” says Roy Tranberg. He continues:
“About two years after surgery, most things have settled. The patients are rehabilitated and back to their daily lives. That is when we see the major improvements. But the research spans even longer. We have groups we have followed for 15 to 20 years to study the long-term effects of different hip and knee prosthetics.”
Treating patients with cerebral palsy
Although research is the main focus, the Gait and Motion Laboratory also has a clinical role. Patients are individuals with severe changes in their movement patterns. A large group consists of children and young people with cerebral palsy (CP), a brain injury affecting the muscles. Many of these patients experience muscle stiffness that prevents them from relaxing. The CP condition, along with the state of their muscles, affects both how the children move and how their skeleton develops as they grow.
“Patients with CP often experience inwardly rotated legs, which is sometimes treated with surgery. We first conduct a thorough investigation, including an analysis in our lab. After surgery, they come back, and we examine how their movement pattern has changed and whether the treatment achieved its intended results. We follow some patients for a long time. Sometimes I see adult patients who started coming here as children, back when the lab was new almost 30 years ago,” says Roy Tranberg, who was involved from the start, initially as an orthopedic engineer tasked with setting up the laboratory.
Aiming to stay at the forefront
Sahlgrenska Academy’s Gait and Motion Laboratory was established thanks to a major donation from the Lundberg Research Foundation. It was inaugurated in 1997. From the beginning, Roy Tranberg and his colleagues have aimed to continuously develop and upgrade the lab and its equipment. They have succeeded several times, often with financial support from the Lundberg Research Foundation.
The most recent major project was completed in 2017, when the lab moved to new, modern facilities at Mölndal Hospital. Soon, another significant development will take place. A grant of 1.4 million SEK from the Lundberg Research Foundation will fund the purchase of a new module based on state-of-the-art motion analysis technology.
The current system requires the person being analyzed to wear 35 reflective markers placed on various parts of the body. Cameras positioned around the room emit infrared light to detect and capture the location of each marker as the person moves.
The collected data is then reconstructed in 3D on a computer and transformed into an animated skeleton. The movement of this skeleton can be analyzed and used by researchers, surgeons, and physical therapists for treatment planning and follow-up. For the system to work, the reflective markers must be both securely attached and placed in the exact same locations on the body each time a person’s movement is analyzed.
Better for patients
With the new technology, Roy Tranberg and his team will be able to perform motion analysis without the need for reflective markers. Instead, they will use a system based on advanced video technology. A large number of high-speed cameras will capture the person’s movement on film. The recorded footage, which consists of vast amounts of data, is processed by a powerful computer. Using specialized software and AI, different parts of the body are identified, allowing researchers to observe how the patients move.
“We get equally precise analyses, but without the hassle of the reflective markers. It saves us a lot of time and simplifies the process for the patients. They do not have to undress. If they wear tight-fitting clothes, they just need to remove their outer layers and shoes before moving around in the room. Many patients, especially children and young people, feel uncomfortable undressing in front of strangers or having things attached to their skin and walking around in a large space. With this new system, we avoid that.”
The grant from the Lundberg Research Foundation will cover the cost of the cameras, computer, software, and installation.
Roy Tranberg:
“We are in the procurement phase. We have waited a little to gain access to the very latest technology. Now, we look forward to getting it up and running.”
Text: Lundberg Foundation