Shock-absorbing goo discovered in bone

New findings show that much of the mineral from which bone is made consists of 'goo' trapped between tiny crystals, allowing movement between them. It is this flexibility that stops bones from shattering.

Latest research shows that the chemical citrate - a by-product of natural cell metabolism - is mixed with water to create a viscous fluid that is trapped between the nano-scale crystals that form our bones.

This fluid allows enough movement, or 'slip', between these crystals so that bones are flexible, and don't shatter under pressure. It is the inbuilt shock absorber in bone that, until now, was unknown.

If citrate leaks out, the crystals -- made of calcium phosphate -- fuse together into bigger and bigger clumps that become inflexible, increasingly brittle and more likely to shatter. This could be the root cause of osteoporosis.

The team from Cambridge's Department of Chemistry used a combination of NMR spectroscopy, X-ray diffraction, imaging and high-level molecular modelling to reveal the citrate layers in bone.

They say that this is the start of what needs to be an entire shift in focus for studying the cause of brittle bone diseases like osteoporosis, and bone pathologies in general. The study is published today in the journal Proceedings of the National Academy of Sciences.