A method for measuring joint kinematics designed for accurate registration of kinematic data to models constructed from CT data

Abstract

A method for measuring three-dimensional kinematics that incorporates the direct cross-registration of experimental kinematics with anatomic geometry from Computed Tomography (CT) data has been developed. Plexiglas registration blocks were attached to the bones of interest and the specimen was CT scanned. Computer models of the bone surface were developed from the CT image data. Determination of discrete kinematics was accomplished by digitizing three pre-selected contiguous surfaces of each registration block using a three-dimensional point digitization system. Cross-registration of bone surface models from the CT data was accomplished by identifying the registration block surfaces within the CT images. Kinematics measured during a biomechanical experiment were applied to the computer models of the bone surface.The overall accuracy of the method was shown to be at or below the accuracy of the digitization system used. For this experimental application, the accuracy was better than ±0.1 mm for position and ±0.1° for orientation for linkage digitization and better than ±0.2 mm and ±0.2° for CT digitization.. Surface models of the radius and ulna were constructed from CT data, as an example application. Kinematics of the bones were measured for simulated forearm rotation. Screw-displacement axis analysis showed 0.1 mm (proximal) translation of the radius (with respect to the ulna) from supination to neutral (85.2° rotation) and 1.4 mm (proximal) translation from neutral to pronation (65.3° rotation). The motion of the radius with respect to the ulna was displayed using the surface models. This methodology is a useful tool for the measurement and application of rigid-body kinematics to computer models.2

Passive strain distribution in the interosseous ligament of the forearm: implications for injury reconstruction

“…A CT scan was then obtained for each specimen. The Plexiglas blocks were used to register the forearm geometry (including radial and ulnar IOL insertions sites) obtained from a CT scan with the data collected during the experiment 18 .…”

“…An initial position of the radial registration block, ulnar registration block, and ISL endblocks were determined using a Microscribe 3DX digitizer (Immersion Corporation, San Jose CA) accurate to within 0.2 mm for position (manufacturer's stated accuracy). Sets of points from three orthogonal planes were collected for each block to establish local coordinate systems, using a previously described technique 18 . This procedure gave the initial relationship between the radius and the ulna and the fixed relationship between the ISL data and the IOL insertion site on the radius.…”

“…The IOL has been shown to resist proximal migration of the radius following radial head excision 11 as well as transfer load from the radius to the ulna when a compressive load is applied to the hand [12][13][14][15] . Strain in the IOL has been studied with load applied to the hand in fixed positions, and was found to be greater in neutral rotation than in supination or pronation 8,18 . Furthermore, in supination, the strains were higher in the distal fibers than in the proximal fibers, whereas in neutral rotation strain was relatively uniform 3,16 .…”

In vivo three‐dimensional motion analysis of the forearm with radioulnar synostosis treated by the kanaya procedure

“…ROM and AOR were visualized using surface bone models. 21 To quantify displacement of the AOR for the radius relative to the ulna, the distance from center of the radial head to the AOR (d-R) and the distance from the fovea on the ulnar head to the AOR (d-U) were investigated assuming that the normal AOR passes through the center of the radial head and fovea on the ulnar head [12][13][14][15][16][17][18][19] ( Fig. 2).…”

“…In normal forearm kinematics, the radius rotates mainly in an arc about the ulna during pronation/supination, and the AOR passes through the center of the radial head and distally through the fovea on the ulnar head. [12][13][14][15][16][17][18][19] In vivo 3D analysis that enables accurate evaluation of ROM and AOR would offer a useful tool for understanding pathological motions of the forearm with deformity or congenital anomaly. These techniques utilize image registration to determine relationships between several image volumes represented at different coordinates via CT. 20 Any in vivo motion of one bone relative to another bone can be analyzed and the AOR associated with any joint motion can be calculated.…”