Evaluation of hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute for posterolateral spinal fusion

Abstract

Background:Autologous cancellous bone is the most effective biological graft material. However, harvest of autologous bone is associated with significant morbidity. Since porous hydroxyapatite and beta-tricalcium phosphate are biodegradable materials and can be replaced by bone tissue, but it lacks osteogenic property. We conducted a study to assess their use as a scaffold and combine them with bone marrow aspirate for bone regeneration using its osteogenic property for posterolateral spinal fusion on one side and autologous bone graft on the other side and compare them radiologically in terms of graft incorporation and fusion.Materials and Methods:Thirty patients with unstable dorsal and lumbar spinal injuries who needed posterior stabilization and fusion were evaluated in this prospective study from October 2005 to March 2008. The posterior stabilization was done using pedicle screw and rod assembly, and fusion was done using hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute over one side of spine and autologous bone graft obtained from iliac crest over other side of spine. The patients were followed up to a minimum of 12 months. Serial radiographs were done at an interval of 3, 6, and 12 months and CT scan was done at one year follow-up. Graft incorporation and fusion were assessed at each follow-up. The study was subjected to statistical analysis using chi-square and kappa test to assess graft incorporation and fusion.Results:At the end of the study, radiological graft incorporation and fusion was evident in all the patients on the bone graft substitute side and in 29 patients on the autologous bone graft side of the spine (P > 0.05). One patient showed lucency and breakage of distal pedicle screw in autologous bone graft side. The interobserver agreement (kappa) had an average of 0.72 for graft incorporation, 0.75 for fusion on radiographs, and 0.88 for the CT scan findings.Conclusion:Hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate seems to be a promising alternative to conventional autologous iliac bone graft for posterolateral spinal fusion.

Radiopacity of alloplastic bone grafts measured with cone beam computed tomography: An analysis in rabbit calvaria

“…This collagen-free layer has an active role absorbing extracellular proteins such as growth factors [19]. Thus, bone grafts containing more HA show more radiopacity during the time of healing [18]. The effect of Osteon  (70% of HA) graft observed in our study seems to be related to this process.…”

“…However, if the graft resorption takes place before the new bone is formed, the bone healing rate may be affected [16]. When this ceramic is mixed with HA, which is a low resorption rate graft [2,17], it improves the formation and remodeling of new bone by providing adequate mechanical resistance [18].…”

Histological Evaluation of Hydroxyapatite Granules with and without Platelet-Rich Plasma versus an Autologous Bone Graft: Comparative study of biomaterials used for spinal fusion in a New Zealand white rabbit model

“…23 In addition, Bansal et al reported that HA in combination with β-tricalcium phosphate and bone marrow aspirate was a safe option for spinal fusion and had comparable effectiveness to an autologous bone graft; the major advantage of this option is the avoidance of donor site morbidity. 2 Based on the results obtained from the current study, it is recommended that future research on HA granules or HA granules plus PRP focuses on the use of these materials in combination with spinal fusion instrumentation in larger-sized animal models. In spinal surgery, higher fusion rates are achieved when instrumentation is used.…”

“…Other studies in the literature are in agreement with these findings. 2,21,22 The porous characteristics of HA potentially affect the histological outcomes of posterolateral lumbar fusion; Motomiya et al found that the highly interconnected porous structure of HA was a promising environment for spinal fusion in a rabbit model in terms of producing fusion masses with higher cellular viability. 23 In addition, Bansal et al reported that HA in combination with β-tricalcium phosphate and bone marrow aspirate was a safe option for spinal fusion and had comparable effectiveness to an autologous bone graft; the major advantage of this option is the avoidance of donor site morbidity.…”

“…1,2 Commonly, bone grafts are harvested from the patient's own bones during surgery. However, serious complications related to the harvesting procedure can arise, such as bleeding, infection and chronic pain at the donor site, as well as increased costs and operating time.…”