Computer‐aided 3D analysis of anatomy and radiographic parameters of the distal radius

Abstract

Introduction This study applied mathematical modeling to examine the anatomy of the distal radius; to define the radiographic parameters in a 3D imaging modality; and to report their normal ranges in the uninjured radius. Materials and methods A series of 50 cone‐beam computed tomography (CBCT) scans of uninjured radii were analyzed using computer‐aided image processing. The radius shape model was used to determine the optimal location for measuring the longitudinal axis. With the axis determined, the volar tilt and radial inclination angles and the areas of the articular facets and their reference points were analyzed. Results The optimal location for determining the longitudinal axis was between 28.8 and 53.3 mm proximally from the articular surface. The mean radial inclination angle was 21.8°. The mean volar tilt angle via the most distal tips of the volar and dorsal rims was 13.0°; along the lunate and scaphoid facets it was 9.1° and 11.2°, respectively. The scaphoid facet was larger than the lunate facet and 25% of it was convex. Conclusions Computer‐aided CBCT image processing offers an advanced tool to record 3D geometry and the radiographic parameters of the osseous structures of the wrist. Analysis of the distal radius' anatomy showed that the longitudinal axis was affected by its measurement location and subsequently also affected the determination of the angular parameters. We also report the variation of the volar tilt along the articular surface and the shapes and sizes of the articular facets.

Computer-based three-dimensional measurement of carpal alignment: measurement techniques and normal ranges

“…A dorsal tangential axis (MC dorsal ) based on the proximal and distal dorsal limits of the axis segment, and an axis perpendicular to the proximal articular surface (MC prox ) were also defined. The geometric axis of the radius was defined using a segment between 28.8 mm and 53.3 mm from the distal articular surface, as reported earlier (Suoja ¨rvi et al, 2021b).…”

“…The bones to be measured were first identified by placing marker points manually on the 3-D rendered bone surface, after which a mathematical model was registered automatically and applied to the wrist in the cone-beam CT scan. Patient specific bone shape was obtained by using deformable shape models (Sotiras et al., 2013; Suojärvi et al., 2021b).…”

Assessment of Progressive Collapsing Foot Deformity Using Semiautomated 3D Measurements Derived From Weightbearing CT Scans

“…Surface shape analysis is used to detect the talar dome and distal tibial articular surface measurement lines. 33 The software calculates various values of which the talar tilt (TT; varus = positive value, valgus = negative value), hindfoot moment arm (HMA; varus = positive value, valgus = negative value), talocalcaneal angle (TCA; axial and lateral), and talonavicular coverage (TNC) were further analyzed. In addition, the presence of medial facet subluxation (percentage of uncoverage >6.4% or incongruence angle >0.5 degrees on coronal WBCT images), sinus tarsi impingement (defined as bone contact between the talus and calcaneus at the level of the sinus tarsi on sagittal WBCT images), and subfibular impingement (defined as bone contact between the distal fibula and the calcaneus on coronal WBCT images) were assessed according to available protocols by the same hyperspecialized foot and ankle surgeon (P.K.).…”

Re: Martins A, Artuso M, Claise JM. Bipedicle strap flaps for reconstruction of longitudinal dorsal finger defects: a review of 42 cases. J Hand Surgery Eur. 2021, 46: 873–6

“…Kramer et al measured the dorsal tilt of the distal radius in CT scans on one single sagittal plane 'where the volar extension of the lunate facet was maximal' and where this 'position corresponded to the centre of the lunate facet' in the coronal plane. As reported earlier, there is a large variation of the volar/dorsal tilt angle at different sagittal planes of the distal articular surface, and in the centre of the lunate facet, the volar tilt is at its smallest (Suoja ¨rvi et al, 2021a). Therefore, it is presumable that dorsal tilt measurements made on one single sagittal CT plane significantly differed from that made in radiograph.…”

“…Therefore, it is presumable that dorsal tilt measurements made on one single sagittal CT plane significantly differed from that made in radiograph. In order to measure radiographic parameters on CT images comparable with that of 2-D radiographs, we suggested that the volar/dorsal tilt angle should be measured on CT scans using the most distal tips of the dorsal and volar rims (Suoja ¨rvi et al, 2021a(Suoja ¨rvi et al, , 2021b. This requires detection and comparison of bony landmarks and reference points in different slices of the sagittal plane.…”