Orthopaedic surgery: ActiveReg realigns the bone using 24 to 28 palpation points instead of more than 700

This closed-loop framework guides the surgeon to areas to palpate rather than specific points, and determines for itself when realignment is sufficient, without any reference to actual conditions on the ground.

In navigated or robotic orthopedic surgery, the bone model must first be realigned to the patient: the surgeon palpates predefined points on the exposed bone surface, a long and delicate step when the opening is reduced. ActiveReg seeks to reduce the number of points needed while clearly guiding the gesture.

Regions rather than points

The system recommends areas for palpation, which allows flexibility on the exact point of contact. A "D-optimal" planner takes into account the points already acquired and the uncertainty of the current registration to choose the next most useful area. An online evaluation, based on the consistency of the measurements and the uncertainty at the points where the surgeon must intervene, decides when to stop, without knowing the actual position.

In simulation on four anatomical scenarios, the accuracy remains competitive with much fewer points. On phantom, with optical or electromagnetic tracking, the registration error is comparable to that of the Gradient-SDF method with only 24 to 28 points, compared to 771 to 1,263.