SEMINAR

DEPARTMENT OF BIOMEDICAL ENGINEERING

Clinically Assessing the Matrix Quality of Bone

Prof. Jeffry Nyman

Department of Orthopaedic Surgery & Rehabilitation, & Biomedical Engineering Vanderbilt University

Abstract

The World Health Organization defines osteoporosis as the existence of a T-score ≤ -2.5 at either the femoral neck, the lumbar spine, or the distal-third radius. The score is the number of standard deviations below normal areal bone mineral density as determined by dual-energy X-ray absorptiometry. While this threshold of -2.5 is useful in deciding to treat a patient with an anti-fracture medication, the vast majority of those who suffer a fragility fracture have a T-score above -2.5. Missing from DXA scores and from FRAX, a widely used on-line fracture risk calculator, is an indication of the patient’s bone matrix quality. That is, the fracture resistance of bone depends on each hierarchical level of bone’s organization, and there are currently no clinical tools that can assess the contribution of the bone matrix, a composite of hydrated type 1 collagen infused nano-sized mineral crystals and non-collagenous proteins, to fracture resistance. Several emerging techniques may be suitable for the clinical assessment of bone matrix quality: impact micro-indentation, bound and pore water concentrations by UTE-MRI, and collagen secondary structure by Raman spectroscopy. This presentation will cover the latest efforts to translate these techniques toward clinical acceptance.