Purpose In the surgical treatment for lower-leg intraarticular
fractures, the fragments have to be positioned and
aligned to reconstruct the fractured bone as precisely as possible,
to allow the joint to function correctly again. Standard
procedures use 2D radiographs to estimate the desired reduction
position of bone fragments. However, optimal correction
in a 3D space requires 3D imaging. This paper introduces a
new navigation system that uses pre-operative planning based
on 3D CT data and intra-operative 3D guidance to virtually
reduce lower-limb intra-articular fractures. Physical reduction
in the fractures is then performed by our robotic system
based on the virtual reduction.
Methods 3D models of bone fragments are segmented from
CT scan. Fragments are pre-operatively visualized on the
screen and virtually manipulated by the surgeon through a
dedicated GUI to achieve the virtual reduction in the fracture.
Intra-operatively, the actual position of the bone fragments
is provided by an optical tracker enabling real-time 3D guidance.
The motion commands for the robot connected to the
bone fragment are generated, and the fracture physically
reduced based on the surgeon’s virtual reduction. To test
the system, four femur models were fractured to obtain four
different distal femur fracture types. Each one of them was subsequently reduced 20 times by a surgeon using our system.
Results The navigation system allowed an orthopaedic surgeon
to virtually reduce the fracture with a maximum residual
positioning error of 0.95±0.3 mm (translational) and 1.4◦ ±
0.5◦ (rotational). Correspondent physical reductions resulted
in an accuracy of 1.03±0.2 mm and 1.56◦ ± 0.1◦, when the
robot reduced the fracture.
Conclusions Experimental outcome demonstrates the accuracy
and effectiveness of the proposed navigation system,
presenting a fracture reduction accuracy of about 1 mm and
1.5◦, and meeting the clinical requirements for distal femur
fracture reduction procedures.