Exactech research showcases importance of surgeon preference during ligament-driven balancing in total knee replacement surgery

At the 34th Congress of the International Society of Technology in Arthroplasty, two Newton® Knee studies were presented that underscore the importance of understanding the impact of surgeon preference during ligament-driven balancing in total knee arthroplasty.

The evolution of technology used to plan and execute total knee arthroplasty has given rise to many different alignment techniques and philosophies. While image-based preoperative planning offers an accurate assessment of patient alignment to the mechanical axis, additional intraoperative soft tissue assessment allows surgeons to fully realize more modern alignment techniques such as functional alignment.

Exactech’s Newton Knee platform captures intraoperative full-range soft tissue laxities, allowing surgeons to visualize predictive surgical alignment and compartmental gaps through ExactechGPS® before any femoral resections are performed. This new research is a catalyst for continued innovation of personalized ligament-driven balance technology.

Research Findings:

Exactech researchers studied 1,155 Newton Knee procedures to determine if a correlation existed between intraoperative laxity curves and chosen tibial insert thickness. The data was used to build surgeon-specific models that could predict tibial thickness preference.

  • The study concluded that the relationship between laxity signature and tibial insert thickness tended to be surgeon-specific and the statistical models could predict their preferred insert thickness with a high level of accuracy.

In another study, a retrospective review was performed on GPS Web, a proprietary cloud-based web database that archives technical case logs. A total of 1,082 cases performed by 20 surgeons to evaluate the laxity signatures were chosen by the surgeons during the intraoperative planning process.

  • The study showed that the targeted knee laxity signature varies based on surgeon preference. Regardless of the status of the posterior cruciate ligament and the compartment side, the relative soft tissue laxity goals from 10° to 120° of flexion were statistically different between the 20 surgeons. Also, this study offered a novel approach to characterize and illustrate the knee laxity signature using heatmaps to better exemplify the variation from surgeon to surgeon.

“As part of Exactech’s commitment to furthering the advancement of technology, these new studies were performed to review surgeon preferences for compartmental laxity differential and ultimate insert thickness,” said Laurent Angibaud, Exactech Vice President of Development, Advanced Surgical Technologies. “The results showed that both laxity signatures and insert thickness tends to be surgeon specific. While the exact laxity required for total knee arthroplasty has yet to be determined, soft-tissue centric solutions like Newton Knee enable a new frontier in terms of personalization of the procedure.”



  1. Angibaud L et al. Building Surgeon-specific Predictive Models of Tibial Insert Thickness using Knee Joint Laxity Signature. Presented at ISTA 2023.
  2. Angibaud L et al. Definition of the laxity goals during TKA tends to be surgeon specific. Presented at ISTA 2023.

About Exactech

Exactech is a global medical device company that develops and markets orthopaedic implant devices, related surgical instruments and the Active Intelligence® platform of smart technologies to hospitals and physicians. Headquartered in Gainesville, Fla., Exactech markets its products in the United States, in addition to more than 30 markets in Europe, Latin America, Asia and the Pacific. Visit www.exac.com for more information and connect with us on LinkedIn, VuMedi, YouTube, Twitter and Instagram. With Exactech by your side, you’ve got EXACTLY what you need.

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