Abstract
PurposeIn the surgical treatment for lower-leg intra-articular 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.Methods3D 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.ResultsThe navigation system allowed an orthopaedic surgeon to virtually reduce the fracture with a maximum residual positioning error of 0.95 pm 0.3,hbox {mm} (translational) and 1.4^{circ } pm 0.5^{circ } (rotational). Correspondent physical reductions resulted in an accuracy of 1.03 ± 0.2 mm and 1.56^{circ }pm 0.1^{circ }, when the robot reduced the fracture.ConclusionsExperimental outcome demonstrates the accuracy and effectiveness of the proposed navigation system, presenting a fracture reduction accuracy of about 1 mm and 1.5^{circ }, and meeting the clinical requirements for distal femur fracture reduction procedures.Electronic supplementary materialThe online version of this article (doi:10.1007/s11548-016-1418-z) contains supplementary material, which is available to authorized users.
Highlights
In the surgical treatment for lower-leg intra-articular fractures, the fragments have to be positioned and aligned to reconstruct the fractured bone as precisely as possible [1], to allow the joint to function correctly again [2], avoiding post-operative chronic pain, a reduced functioning of the limb, arthritis, and as a consequence, potential disablement [3,4].Currently, the treatment for lower-limb joint fractures consists in anatomical surgical reduction and rigid internal fixation, involving an open incision into the joint, manual reduction in the fracture, and fixation using a metallic plates and screws, or intramedullary nails [5]
We present a new navigation system that introduces pre-operative and intra-operative 3D guidance to reduce an intra-articular fracture using the robotic system developed at the Bristol Robotics Laboratory (BRL) and described in [23]
The manipulation pins are connected to the robotic system [23], and the navigation system generates the motion commands to physically reduce the fracture based on the virtual reduction plan performed by the surgeon
Summary
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
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