Positioning accuracy of a patient-tailored rimmed wedge implant for corrective osteotomy of the distal radius.

Conventional corrective osteotomy surgery is based on 2-D imaging for planning and evaluation of bone positioning. In this feasibility study we propose and evaluate the use of 3-D preoperative planning and design of a custom rimmed wedge to be inserted into the osteotomy gap. The shape of the wedge provides 3-D bone positioning as planned, while the rims keep the bone segments in place. The method is evaluated experimentally using 3-D printed radii specimens of five different malunion patients, as well as in a human cadaver specimen. Positioning was accurate and reproducible showing residual displacements along the x-, y- and z-axes of (mean ± SD): (-0.19 ± 0.75, 0.38 ± 1.09, and 0.47 ± 0.48) mm and residual rotations about these axes of (mean ± SD): (-1.22 ± 1.66, -0.40 ± 0.93, and -0.33 ± 1.50)° for artificial bone specimens. The cadaver experiment showed similar displacements along the x-, y- and z-axes (-0.17, 1.11, and -0.35) mm and residual rotations about these axes (-2.93, -1.53, and 2.31)°. Positioning by inserting a rimmed wedge in corrective osteotomy surgery is accurate with residual errors comparable to bilateral differences. The method seems promising for future utilization in corrective osteotomy surgery and may ultimately render the procedure minimally invasive.