Abstract
Platelet-rich plasma (PRP) is an autogenous source of growth factor and has been shown to enhance bone healing both in clinical and experimental studies. PRP in combination with porous hydroxyapatite has been shown to increase the bone ingrowth in a bone chamber rat model. The present study investigated whether the combination of beta tricalcium phosphate (beta-TCP) and PRP may enhance spinal fusion in a controlled animal study. Ten Danish Landrace pigs were used as a spinal fusion model. Immediately prior to the surgery, 55 ml blood was collected from each pig for processing PRP. Three-level anterior lumbar interbody fusion was performed with carbon fiber cages and staples on each pig. Autogenous bone graft, beta-TCP, and beta-TCP loaded with PRP were randomly assigned to each level. Pigs were killed at the end of the third month. Fusion was evaluated by radiographs, CT scanning, and histomorphometric analysis. All ten pigs survived the surgery. Platelet concentration increased 4.4-fold after processing. Radiograph examination showed 70% (7/10) fusion rate in the autograft level. All the levels with beta-TCP+PRP showed partial fusion, while beta-TCP alone levels had six partial fusions and four non-fusions ( P=0.08). CT evaluation of fusion rate demonstrated fusion in 50% (5/10) of the autograft levels. Only partial fusion was seen at beta-TCP levels and beta-TCP+PRP levels. Histomorphometric evaluation found no difference between beta-TCP and beta-TCP+PRP levels on new bone volume, remaining beta-TCP particles, and bone marrow and fibrous tissue volume, while the same parameters differ significantly when compared with autogenous bone graft levels. We concluded from our results in pigs that the PRP of the concentration we used did not improve the bone-forming capacity of beta-TCP biomaterial in anterior spine fusion. Both beta-TCP and beta-TCP+PRP had poorer radiological and histological outcomes than that of autograft after 3 months.