gms | German Medical Science

Objectives/Interrogation: In articulations, the morphology of the joint dictates the way forces will travel through it. Understanding wrist structure and consequently function is complicated by multiple joints and ligamentous structures leading to a limited ability to diagnose and treat wrist conditions. Our purpose was to assess the associations between intracarpal measurements performed on radiographs (2D) to measurements performed on clinical 3-dimensional (3D) computed tomography (CT).

Methods: Retrospective review of normal wrist radiographs and corresponding normal wrist CT scans. Only imaging pairs with normal carpal alignment and technically optimal imaging were included. Evaluations included lunate, capitate and wrist type, capitate circumference and area, percent capitate circumference and area that articulates with the lunate, scapholunate ligament, scaphoid, hamate, trapezoid, base of the index and middle and ring metacarpal bones.

Results and Conclusions: There were more lunates type 1 than 2. Lunate and capitate type were correlated between X-rays and CT scans (lunate: r=0.78 p<0.001,capitate: r= 0.75 p<0.001). Lunate type 2 was seen more often on CT scan. Percent lunate-hamate contact on CT was a significant predictor of lunate type 2 on X-rays p<0.001. 7.8% contact on CT scan between lunate and hamate provided a sensitivity of 100% and specificity 79.4% for type 2 lunate. Other measurements correlated between 2D and 3D measurements were capitate -base of index and ring metacarpals and capitate-hamate contact area. Other measurements were not correlated or correlated weakly (Table 1).

Technical difficulties stemmed from the direction of the cuts on the coronal CT.

Conclusions:

1.

This study supports the use of plain films and CT scans in the clinical setting especially to evaluate lunate and capitate type.

2.

The retrospective nature of this study limited the technical quality of the measurements.

3.

Further study using different methods may aid in a more exact evaluation of surface contact area.