Biomechanical study of human cadaveric lumbar spine reinforced by newly developed hydroxyapatite bone cement

The compression strength of the lumbar spine reinforced by newly developed hydroxyapatite (HA) bone cement was evaluated using a mechanical testing machine. Sixteen cadaveric lumbar vertebrae obtained from nine subjects (five men, four women) were used. The specimens were randomly divided into two groups. In group A ( n = 8), HA bone cement was injected into the vertebral body through curetted pedicles using specially designed needles and then pushed into the vertebral body by the surgeon's finger, simulating open surgery. In group B ( n = 8) the cement was injected using 16-gauge Ostycut biopsy needles via the pedicles through both sides, simulating percutaneous injection. The initial ultimate compression strength of the specimens was 28.6 +/- 13.4 MPa in group A and 25.2 +/- 12.6 MPa in group B. The value after reinforcement was 35.6 +/- 12.9 MPa in group A and 30.4 +/- 14.8 MPa in group B. There was no significant difference between the ultimate strength of the intact specimen and that after reinforcement. The present study demonstrated biomechanical characteristics of vertebral body fractures reinforced with newly developed HA bone cement.