The use of calcium phosphate cement in less invasive surgical treatment for low back pain associated with osteoporosis.

Abstract

We have developed transpedicular injection of bioactive calcium phosphate cement (CPC) into the vertebral body for repair of osteoporotic vertebral compression fracture and the pseudarthrosis without neurological involvement as a less invasive surgical treatment for back pain in patients with osteoporosis who present with fresh vertebral compression fractures associated with acute back pain, vertebral pseudarthrosis resulting from a disturbance of bone union processes, and severe kyphotic deformity. The CPC used is injectable, non-exothermic, self-setting, and bioactive with osteoconductivity, and sets by hydration to change composition into carbonated hydroxyapatite. Its compressive strength increases over time, and reaches the maximum in about 7 days after injection. The maximum value is over 80 MPa, which is strong enough to reinforce the collapsed vertebrae. Traditionally, these painful conditions have been dealt with using conservative treatment, if they are not accompanied by neurological deficits. However it is also true that satisfactory results are not always obtained by such treatment. We have studied 19 patients who presented with fresh vertebral compression fracture, and 17 patients with delayed union or pseudarthrosis with at least a 3-month follow-up. Radiological examinations indicate that all fractures have been successfully repaired except for one case of pseudarthrosis. Pre-Post operative evaluations were carried out using a 10-point pain rating scale. For fresh fracture cases, the average 10-point pain scale was 8.1 preoperatively and 0.4 immediately postoperatively, and was 0.7 at final follow-up averaging 19 months after surgery. Wedging rate, which is defined as a percentage of the anterior vertebral height to the posterior one in a lateral x-ray film, is 65% before treatment and 84% immediately after treatment. Seventy-eight percent was maintained up to the final follow-up. No loss of correction was observed after 1 month. For delayed union or pseudarthrosis, the average pain scale was 7.2 preoperatively, 1.5 postoperatively, and 1.7 at final follow-up of average 13 months after surgery. The wedging rate is 30% preoperatively, 59% postoperatively, and 49% at final follow up. Correction loss occurred within 3 months postoperatively and did not change thereafater. The transpedicular injection of CPC into the vertebral body could be a valuable addition to the physician’s strategy in the treatment of back pain due to osteoporotic vertebral fractures and associated conditions, providing early pain relief and mobility, and good correction of the collapsed deformity.