Among the most common causes of upper extremity fracture is a fall on an outstretched
hand. The result of this is often a fracture of the distal radius, and the most common of
these is the two part Colles’ fracture. Understanding the fracture in greater detail can lead
to better clinical treatment of the injury. Much study has been done in an attempt to
understand the biomechanical factors that lead to the fracture and to recreate the event in
multiple media with varying boundary conditions.
In this study, we focused our efforts on the impact loading of forearm cadavera in an
attempt to recreate, as best as possible, the physiologic events of a forward fall onto an
outstretched hand. Fluoroscopic data was taken prior to testing to dimension the cortical
bone of the radius, and afterwards to assess and characterize fracture patterns. A custom
drop tower was designed and constructed to dynamically load cadaveric forearms to
failure. Furthermore, impact mechanics theory was used to estimate the effective load
applied with each test.
It was determined that 3046 N ± 650 N, with a ratio of axial to bending loads of 2.8 ± 1.0,
was necessary to impart a Colles’ fracture in completely intact cadaveric forearms. This
load fell within published ranges associated with distal radius fractures. Testing included
15 cadaveric samples (11 female and 4 males). Though considered at first, no direct
correlation was found between the body mass index of each donor and the load required
to fracture the radius. Results also indicated that females were more susceptible to Colles’
fractures than were males. This may be due in part to the higher average age of the
female donors. We concluded that it is possible to produce Colles’ fractures with a relatively high rate of
success. However, uncontrollable biological factors provided variation such that a
completely repeatable fracture pattern across the sample population was not achieved.
Furthermore, while an impact model could be the most accurate recreation of a forward
fall, more research is needed to truly validate the results obtained through this impact
based body of work.