How to determine the bone mineral density of the distal humerus with radiographic tools?

Abstract

Introduction: The aim of this study was to investigate three methods of prediction of the bone quality of the distal humerus: dual-energy X-ray absorptiometry (DEXA), Ct-Scan and plain radiographs.

Materials and methods: The bone mineral density (BMD) of 21 cadaveric distal humerus was determined using DEXA at two levels. Then a CT-scan and anteroposterior radiographs were taken. The cancellous density was estimated with the CT-scan. The cortico-medullar index (CMI) was calculated as cortical thickness divided by total bone thickness on AP views.

Results: A significant positive correlation was found between the BMD of the epiphysis and the CMI of r = 0.61. The mean BMD of the distal humerus was 0.559 g/cm(2). Male specimens showed a significantly higher BMD than females. The mean CMI of diaphysis was 1.431 and the mean BMD of the metaphysis region was 0.444 g/cm(2).

Discussion: More than a direct evaluation of the bone density with a CT-scan, the CMI of the distal humerus diaphysis is a predictor of the bone quality of the distal humerus. This should be of great help for the surgeon's decision making in case of fracture of the distal humerus, as open Reduction and Internal Fixation (ORIF) of fractures of the distal humerus can lead to failure due to poor bone quality.

Level of evidence: Basic Science Study, Anatomic Cadaver Study.

Keywords: Bone mineral density; Distal humerus; Dual energy X-ray absorptiometry; Osteoporosis; Quantitative CT.