Computer-Based Periaxial Rotation Measurement for Aligning Fractured Femur Fragments from CT: A Feasibility Study

Abstract

A new computer-based method for measuring periaxial rotation of healthy and fractured femurs from preoperative CT during closed femoral fracture reduction surgery is described. The method provides a comparative quantitative measure to align the distal and proximal femur fragments based on periaxial rotation. The periaxial rotation is defined in terms of patient-specific bone features. An algorithm for automatically extracting these features from the CT based on this definition has been developed. The algorithm extracts the condyle landmarks and neck axis of the healthy bone, determines its periaxial rotation, and extrapolates this data, assuming mirror symmetry between the healthy and fractured bones, to measure periaxial rotation between the fractured fragments. Unlike existing techniques, the method requires minimal user intervention. In a feasibility study, the method was applied to five dry femurs and one patient data set, and simulated a reduction based on the periaxial measurements with satisfactory results. The experiments showed the measured angle on the fractured femur to be within 1-4.5 degrees of that of the healthy bone.

Development and validation of a new approach for computer-aided long bone fracture reduction using unilateral external fixator

“…In recent years, computer assisted navigation technology has been applied to perform controlled fracture reduction using either fluoroscopy (Hofstetter et al, 1999(Hofstetter et al, , 2000 or computed tomography (CT) (Hu¨fner et al, 2001;Ron et al, 2002;Joskowicz et al, 1998) based systems. For the fluoroscopy-based system, the bone fragments are displayed through superimposed line…”

“…The 3D coordinates of the fiducial markers were then used to define the local coordinate systems of the distal and proximal assemblies. Principle axes of each fracture fragment were then identified using the principle axis transformation (PAX) technique (Tsao et al, 1998;Ron et al, 2002). PAX determines a set of three orthogonal axes representing the major axes of mass distribution within a rigid object.…”

Hierarchical CT to Ultrasound Registration of the Lumbar Spine: A Comparison with Other Registration Methods

“…A set of three orthogonal axes representing the major axes of mass distribution within each vertebra (i.e., principal axes) are calculated using the principal axis transformation technique. 27,30 Assuming each voxel is a unit mass, the principal axes of a vertebra are the 3 eigenvectors of the following covariance matrix:…”

A novel master–slave teleoperation robot system for diaphyseal fracture reduction: a preliminary study

“…[17] Accuracy is also an important index, because the load is concentrated during standing and walking, a precise operation on the fractured bone fragments is needed for strong osseointegration. [18,19] We designed a master-slave robot system for diaphyseal fracture reduction that accounted for these factors. Figure 1 illustrates the robot system and the component relationships.…”