The cortical thickness of the proximal humeral diaphysis predicts bone mineral density of the proximal humerus

Abstract

The operative treatment of fractures of the proximal humerus can be complicated by poor bone quality. Our aim was to evaluate a new method which allows prediction of the bone quality of the proximal humerus from radiographs. Anteroposterior radiographs were taken of 19 human cadaver humeri. The cortical thickness was measured at two levels of the proximal humeral diaphysis. The bone mineral density (BMD) was determined for the humeral head (HH), the surgical neck (SN), the greater tuberosity (GT) and lesser tuberosity (LT) using dual-energy x-ray absorptiometry. The mean cortical thickness was 4.4 +/- 1.0 mm. Specimens aged 70 years or less had a significantly higher cortical thickness than those aged over 70 years. A significant positive correlation was found between cortical thickness and the BMD for each region of interest. The cortical thickness of the proximal diaphysis is a reliable predictor of the bone quality of the proximal humerus.

Deltoid Tuberosity Index: A Simple Radiographic Tool to Assess Local Bone Quality in Proximal Humerus Fractures

“…Therefore, the threshold value less than 1.4 for the deltoid tuberosity index may be only an approximation for low local bone quality of the proximal humerus and further investigations are needed to ensure its clinical relevance in the treatment of fractures. Regarding the Tingart measurement, the originally proposed threshold value (\ 4 mm) [25] showed very low sensitivity (only 0.45) in our setting, which is in accordance with findings by Mather et al [16]. They suggested a possible threshold value less than 6 mm for the Tingart measurement to predict osteoporosis of the proximal femur and the lumbar spine.…”

“…Whereas the latter has been proven to correlate well to DXA measurements of other anatomic sites (distal radius, proximal femur) [16], our study is the first, to our knowledge, to compare the Tingart measurement with local BMD measured by pQCT of the proximal humerus. A possible explanation why the Tingart measurement was at a disadvantage to the deltoid tuberosity index in this respect could be that Tingart defined different regions of interest in the proximal humerus and found the best correlation to BMD of the greater tuberosity [25,26]. We were not able to account specifically for this region of interest with the pQCT protocol used in our study [14].…”

“…The need to correct magnification to calculate the absolute value of the Tingart measurement is a drawback as not every radiograph has the needed reference. Another disadvantage of the Tingart measurement is defining the height of level 1, which is imperative for determining level 2 [25]. This proximal diaphyseal area is often part of the fracture, which makes measurement difficult.…”

“…Two orthopaedic consultants (CS and EB) independently measured the ( Fig. 2) deltoid tuberosity index and the Tingart measurement [25] twice on the AP radiographs.…”

“…There is evidence, however, that the BMD of the upper limb (distal radius) is less than that of typically measured sites (such as the proximal femur and lumbar spine) in patients with proximal humerus fractures [27]. Thus, preoperative assessment of BMD of the proximal humerus has become the focus of some studies, with methods ranging from measuring the cortical thickness on AP radiographs, to calculating BMD on peripheral quantitative CT (pQCT) scans [6,8,9,14,16,21,25,26]. Barnett and Nordin [3] were the first to invent a cortical index to assess local bone quality of the hand and femur.…”