Multiplanar reformation computed tomography for carpal malalignment

Comparison of computer-aided and manual measurements in the evaluation of carpal alignment

The purpose of this study was to compare computer-aided analysis and different methods of manual measurements in the evaluation of carpal alignment. The radioscaphoid, radiolunate, radiocapitate and radiometacarpal angles were measured on cone-beam computed tomography (CT) scans of 30 healthy wrists by automated software (Disior Ltd.) and by hand surgeons using lateral radiographs reconstructed from the CT data. Hand surgeons were either given (n = 6) or not given (n = 7) prior instructions on how to perform the measurements. Inter- and intra-observer reliability of manual measurements ranged from good to excellent (intra-class correlation coefficients [ICC] 0.77-0.99), being highest in specialists with standardized methods and in reconstructed radiographs with bone overlap digitally removed. Computer-aided software provided excellent intra-observer reliability (ICC 0.94-1.00) consistently and values that were highly comparable (mean difference range 1°-7°) with the manual measurements made in optimal settings. Computer-aided software provides an accurate and repeatable method to measure carpal alignment in CT scans, minimizing observational errors.

Defining trapezial dysplasia - analysis of trapezial inclination in a normal population

We assess the distribution of trapezial inclination in a young population in order to propose a threshold for trapezial dysplasia. One hundred peritrapezial views were reconstructed from wrist computed tomography scan datasets to measure trapezial inclination. Seventy peritrapezial views were constructed from 10 datasets to assess the influence of radiograph rotation. Mean trapezial inclination in our population was 8° (range 0.2-17.9). Fifteen degrees of radiographic pronation or supination did not alter trapezial inclination significantly. Intra-rater consistency and absolute agreement had an interclass correlation (ICC) of 0.95. Inter-rater consistency and absolute agreement had an ICC of 0.88. Trapezial inclination is a reliable measurement for trapezial dysplasia with an excellent intra-rater and good inter-rater reliability and does not change significantly with 15° of radiographic pronation or supination. These normal values can be used to propose a threshold for trapezial dysplasia in the management of trapeziometacarpal joint instability in the younger population.Level of evidence: IV.