Browsing by Author "Zunariah Buyong"

BACKGROUND: Hydroxyapatite is widely used as bone graft substitute. Platelet-rich plasma (PRP) is enriched with growth factors. Hypothetically combination of PRP and hydroxyapatite would augment bone formation effect of hydroxyapatite and widen its application in spinal fusion. OBJECTIVE: To compare new bone formation between hydroxyapatite granules alone; hydroxyapatite granules in combination with PRP; and autograft as the control. METHODOLOGY: First phase of the study dealt with the production of PRP and characterization of platelets by platelet counts and platelet morphology. Second phase involved spinal fusion surgery in twenty-four adult New Zealand white rabbits. All the animals underwent single level bilateral intertransverse process fusion at L5-L6 vertebrae. One side of the animals received either hydroxyapatite granules alone (HA group) or combination of hydroxyapatite granules and PRP (HAPRP group) while the contralateral side received autograft (Autograft group). Four animals each in HA vs. Autograft and HAPRP vs. Autograft were assessed either at 6, 12 or 16 weeks by plain radiograph, computed tomography scan, undecalcified histology, histomorphometry and scanning electron microscopy. Using the histomorphometric data, the mean percentage of new bone areas over the corresponding fusion masses was compared between groups. RESULTS: Mean platelet count in whole blood and PRP were 363 x 103/3/uL (SD 112 x 103) and 1596 x 103/3uL (SD 512 x 103) respectively. Platelets showed minimal morphological changes. Autograft group showed significantly more new bone than HA and HAPRP at 6, 12 and 16 weeks (P=0.004, P<0.001 and P<0.001 respectively) but no significant difference between HA and HAPRP at 6, 12 and 16 weeks (P=0.154, P=0.929, P=0.487 respectively). Autograft, HA and HAPRP groups showed direct contact with new bone but Autograft demonstrated better integration than HA and HAPRP groups. CONCLUSION: Hydroxyapatite granules alone or in combination with PRP could not challenge autograft as bone graft substitute for posterolateral lumbar fusion. [305 words]

Calcium phosphate is an ideal bone substitute material that is widely used for bone repair due to its excellent biological properties including biocompatibility and osteoconductivity. In order to improve the properties of calcium phosphate materials for clinical use, a new injectable self-hardened synthetic bone cement (Osteopaste) was developed. Osteopaste consists of tetra-calcium phosphate (TTCP) and tricalcium phosphate (TCP) powder. It was intended for the treatment of bone fracture or reconstruction of bone defects. The objective of this study was to compare bone formation between Osteopaste and commercialized synthetic bone grafts; JectOS (calcium phosphate) and MIIG-X3 (calcium sulphate) at three different assessment periods. The first phase of the study was to establish the critical size defect in New Zealand White rabbit model. The second phase involved the implantation of Osteopaste, JectOs and MIIG-X3 in critical size defects. Thirty-nine New Zealand White rabbits were divided into four groups (Osteopaste, JectOs, MIIG-X3 and sham). Each group was further divided into three subgroups according to the assessment period either at 6, 12 or 24 weeks. Each subgroup consisted of four rabbits except the sham group which consisted of only one rabbit. A critical size defect of approximately 4.5 mm (width) X 9.0 mm (length) was created at the proximal tibial metaphysis of rabbit's right leg and then implanted with either Osteopaste, JectOs or MIIG-X3. At each assessment period, plain radiograph and computed tomography (CT) scan were performed before the animals were sacrificed for undecalcified histology, histomorphometry and scanning electron microscopy assessments. Using the histomorphometric data, the mean percentage of new bone areas and the length of unbridged defects were compared between groups. In this study, a simple and safe method for performing critical size defect at proximal tibial metaphysis was established. The Osteopaste group exhibited radiographic density in between JectOS and MIIG-X3. The critical size defect in Osteopaste group was bridged by new bone at 12 weeks. In MIIG-X3 group, the defect was bridged at 24 weeks whereas in JectOS group, the defect was not bridged at all assessment periods. New bone area was the largest in MIIG-X3 group followed by Osteopaste and JectOS groups. Osteopaste had formed direct bonding with host bone without intervening soft tissue compared to JectOS and MilG-X3. There were significant differences in new bone area percentages between Osteopaste, JectOs and MIIG-X3 at 6, 12 and 24 weeks post-surgery (P<0.0001 ). In conclusion, the performance of Osteopaste to promote new bone formation is in between JectOS and MIIG-X3.