Background: In orthopaedic surgery, many interventions involve freehand bone cutting with an oscillating saw. Such freehand procedures can produce large cutting errors due to the complex hand-controlled positioning of the surgical tool. This study was performed to investigate the potential improvements in cutting accuracy when computer-assisted and robot-assisted technologies are applied to a freehand bone-cutting process when no jigs are available.
Methods: We designed an experiment based on a geometrical model of the cutting process with use of a simulated bone of rectangular geometry. The target planes were defined by three variables: a cut height (t) and two orientation angles (β and γ). A series of 156 cuts were performed by six operators employing three technologically different procedures: freehand, navigated freehand, and robot-assisted cutting. After cutting, we measured the error in the height t, the absolute error in the angles β and γ, the flatness, and the location of the cut plane with respect to the target plane.
Results: The location of the cut plane averaged 2.8 mm after use of the navigated freehand process compared with 5.2 mm after use of the freehand process (p < 0.0001). Further improvements were obtained with use of the robot-assisted process, which provided an average location of 1.7 mm (p < 0.0001).
Conclusions: Significant improvements in cutting accuracy can be achieved when a navigation system or an industrial robot is integrated into a freehand bone-cutting process when no jigs are available. The procedure for navigated hand-controlled positioning of the oscillating saw appears to be easy to learn and use.
Clinical Relevance: These findings support a recommendation for further study to determine if the improvements in cutting accuracy observed in vitro are possible in vivo.
1Centre for Research in Mechatronics, Université catholique de Louvain, Place du Levant 2, B-1348 Louvain-la-Neuve, Belgium. E-mail address for O. Cartiaux: firstname.lastname@example.org
2Department of Orthopaedic Surgery, Université catholique de Louvain, Avenue Mounier 53, 1200 Bruxelles, Belgium
3LIRMM, CNRS-Université Montpellier 2, 161 rue Ada, 34392 Montpellier CEDEX 05, France