Tuesday, February 26, 2008

Dinosaurs Bones and Foot Pain in a Runner

This is a metatarsal bone from the dinosaur Deltadromeus agilis:

(courtesy PaleoDirect)

The metatarsal bones of a human are a little smaller, but serve the same function. They help form the longitudinal arches along the inner and outer sides of the foot. Theodorou et al. (Radiology 2003;226:857-865) wrote a beautiful paper describing the anatomy of the base of the fifth metatarsal. Here is a photograph from that paper:


Surgical scissors are inserted under the peroneus brevis tendon (PB), close to the base of the fifth metatarsal (MT5). The lateral component of the plantar aponeurosis (PAL) that attaches to the fifth metatarsal base is well seen.

Thedorou et al. suggested that the tuberosity avulsion fractures are due to violent traction at the insertion of the conjoined fibers of the lateral component of the plantar aponeurosis and the peroneus brevis tendon.

When the lateral foot is stressed, biomechanical failure can occur at bone or in the soft tissue. When the bone fails, the result is a fracture. Soft tissue failure can occur at the insertion of the peroneus brevis and/or the lateral component of the plantar aponeurosis. Here is a 67 year-old runner with two months of lateral midfoot pain:



Sagittal (top set) and axial (bottow set) images demonstrate marked thickening and irregularity of the distal lateral component of the platar aponeurosis (red arrows). A comparison image from a different patient with normal anatomy is provided (green arrows).

Thus, this patient's symptoms are due to a partial tear of the lateral component of the plantar aponeurosis. Runners hate to stop running, but she is going to have to do that to get better.

I suspect that a dinosaur with the same problem would stop running, too.



Vic David MD
Orthoradiology.com

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