Efficacy of calcium sulfate plus decompression bone in lumbar and lumbosacral spinal fusion: preliminary results in 40 patients

Objective: To compare the efficacy of calcium sulfate pellets plus bone obt ained from decompression with fresh autologous iliac crest bone in lumbar a nd lumbosacral spinal fusion with decompression. Design: A prospective rand omized clinical trial. Setting: Four tertiary care centres in Halifax, NS. Patients: All were consenting, skeletally mature and suffering from degener ative disc disease or spondylolisthesis. The first 40 patients from a singl e test centre are reported; 32 of these had completed I-year follow-up. Int erventions: Posterolateral lumbar or lumbosacral spinal fusion with spinal canal decompression and randomized placement of test material (decompressio n bone plus an equal volume of calcium sulfate pellets) on one side and con trol material (autologous posterior iliac crest bone of equal volume to the test material) on the contralateral side, which allowed subjects to act as their own control. Outcome measures: Assessment of bone formation by radio graphic evaluation at 6 and 12 months after fusion by an independent muscul oskeletal radiologist blinded to the placement of test material. Results. A t 6 and 12 months after fusion, 78% and 88% of patients, respectively, show ed bone formation at the test site that was 75% to 100% of, equal to or mor e than that at the control site. Increases in bone formation at 6 and 12 mo nths were almost identical at both sites. Smoking status, patient gender or age, instrumentation used and volume of graft used were not predictive of outcome. Conclusions: Calcium sulfate pellets plus decompression bone provi ded bone formation equivalent to autologous iliac crest bone in a majority of patients. Calcium sulfate pellets plus decompression bone may provide a viable alternative to autologous iliac crest as a graft material for spinal fusion.