Efficacy of platelet-rich plasma impregnation for unidirectional porous β-tricalcium phosphate in lateral lumbar interbody fusion: study protocol for a prospective controlled trial

BACKGROUND: The use of platelet-rich plasma has been increasing in spinal fusion surgery. However, the efficacy of platelet-rich plasma in lateral lumbar interbody fusion is unclear. In Japan, Affinos,® (Kuraray Co., Tokyo, Japan), a β-tricalcium phosphate artificial bone, has been increasingly used for spinal fusion. The purpose of this trial is to demonstrate whether Affinos® impregnated with platelet-rich plasma can achieve a higher fusion rate and better clinical outcomes than Affinos® alone. METHODS: The current study is a prospective randomized controlled trial. This trial will include consecutive patients scheduled for lateral lumbar interbody fusion. An intervertebral cage for lateral lumbar interbody fusion has two spaces for bone grafts. As a consequence, two bone grafts are inserted at each intervertebral level. In this study, an artificial bone with platelet-rich plasma will be inserted into one space, and an artificial bone without platelet-rich plasma will be inserted into the other space. We will compare the fusion rates between the bone grafts with and without platelet-rich plasma. Our primary endpoint will be the interbody fusion rate at 1 year after surgery. DISCUSSION: This trial will verify the efficacy of platelet-rich plasma with Affinos® for bony fusion in lateral lumbar interbody fusion. It will also provide substantial evidence for the effectiveness and safety of platelet-rich plasma in spinal fusion surgery. TRIAL REGISTRATION: Japan Registry of Clinical Trials (jRCT) jRCTb032200199. First registered on 13 November 2020. jRCT is approved as a member of the Primary Registry Network of WHO ICTRP.