gms | German Medical Science

Objective: We developed a method to quantitatively analyze fracture fragment morphology on three-dimensional computed tomography images (Q3DCT) in terms of size, shape, and articular surface area.

Methods: Forty-six consecutive adult patients with a fracture of the radial head with CT scans were analyzed with Q3DCT. We defined an unstable fracture as complete loss of cortical contact of at least one fragment. Three patients had a Mason type 1 fracture (all stable), 26 patients a type 2 fractures (7 stable (27%) and 19 unstable (73%)), and 17 patients a type 3 fracture (all unstable). The volume and articular surface area of each articular fracture fragment was measured. We defined a small fragment as having a volume of less than 100 mm³ or an articular surface of less than 100 mm².

Results and conclusions: Partial head fractures (Mason 2, 26 fractures) are usually multi-fragmented (19 of 26, 73%) and often have small fragments by volume (32 fragments) and surface area criteria (46 fragments), particularly when the fracture is displaced and unstable. Only 4 of the patients (25%) with whole head fractures (Mason 3) had greater than 3 fragments, but 9 (69%) of the fractures with 3 or fewer fragments had small fragments. According to this preliminary modeling using quantitative 3DCT analysis of radial head fracture morphology, partial head fractures are often complex and difficult to repair (small fragments), and the criterion of 3 or greater fragments as a threshold for prosthetic replacement of a whole-head fracture may not account for all aspects of fracture complexity including fragment size.