Bone structure and bone strength of the proximal humeral head affect the stability of the internal fixation material at the fracture operation. We evaluated the relationship between the trabecular structure and the bone strength in the proximal humeral head using cadaver humerus. 7 cadavers humerus ( mean age 79.6 ) was analyzed by micro CT. Bone volume/ tissue volume, trabecular number, trabecular thickness, trabecular separation, number of node and length of node strut were measured as trabecular parameters at 3 regions of interest ( region A : top of humeral head, B : middle of humeral head and C : neck ). On the coronal plane the osteotomy was performed on the middle of humeral head and sliced 1 cm thickness. The maximum load value was measured by the compression test using a universal material examination machine ( Instron 4505 )at region A and B. There were significant difference between region A and C, B and C concerning Bone volume/ tissue volume, trabecular number, trabecular separation node number, number of node and length of node strut ( p < 0.05 ). There were significant difference between region A and B( p < 0.05 ) concerning bonestrength. There were positive correlation between bone volume/ tissue volume and bone strength, trabecular number and bone strength, trabecular thickness and bone strength, node number and bone strength and node length and bone strength( p < 0.01). Our result shows the trabecular structure and bone strength at the superior region in the proximal humeral head had better than other regions. There were positive correlation between trabecular parameters and bone strength. Above results indicate that better stabilization is achieved by inserting the screw tip on the superior proximal humeral head at the fracture operation.
