抄録
Since bone mineral density (BMD) and bone strength of the proximal humeral head affect the stability of the internal fixation material at the operative treatment, we tried to evaluate the relationship between BMD and bone strength in the proximal humeral head cancellous bone using cadaver humerus. The BMD of 6 cadavers humerus (2 males and 4 female, mean age 83.2). BMD was analyzed by XP-26 (Norland Co.). BMD, distinguished by several colors, was measured at 3 regions of interest (region A: top of humeral head at the acromion side, region B: the area of subchondral bone at the glenoid side, region C: the middle of the humeral head). On the coronal plane the osteotomy was performed on the middle of humeral head and sliced 1 cm thickness. The maximum load value at three regions were measured by the compression test of the humeral head slice using a universal material examination machine (Instron 4505) with the compression bar (8.5 mm diameter) at the speed 0.04 mm/sec. Mean BMD (g/cm2) of the region A was 0.469, B 0.712 and C 0.466. Region B was significant difference from A and C (p=0.05). The mean maximum load value (N) was 134 at region A, 211 at B and 84 at C. There were significant difference A Vs B and B Vs C (p=0.05). There was positive correlation between BMD and the bone strength at the region A and B. Our result shows that the BMD measurement is the useful method to judge the stability when elderly patients with proximal humeral head fracture are treated by screw fixation.
