Dosing Strategy for Osteobiologics Used in ACDF Surgery: Influence on Fusion Rates and Associated Complications. A Systematic Literature Review.

Study Design: Systematic review.

Objective: To assess the available evidence related to dose-dependent effectiveness (i.e., bone fusion) and morbidity of osteobiologics used in anterior cervical discectomy and fusion (ACDF).

Methods: Studies with more than 9 adult patients with degenerated/herniated cervical discs operated for one-to four-levels ACDF reporting used osteobiologics doses, fusion rates at six months or later, and related comorbidities were included. PubMed, EMBASE, ClinicalTrials, and Cochrane were searched through September 2021. Data extracted in spread sheet and risk of bias assessed using MINORS and Rob-2.

Results: Sixteen studies were selected and sub-grouped into BMP and non-BMP osteobiologics. For the 10 BMP studies, doses varied from 0.26 to 2.1 mg in 649 patients with fusion rates of 95.3 to 100% at 12 months. For other osteobiologics, each of six studies reported one type of osteobiologic in certain dose/concentration/volume in a total of 580 patients with fusion rates of 6.8 to 96.9% at 12 months. Risk of bias was low in three of the 13 non-randomized (18.75%) and in all the three randomized studies (100%).

Conclusions: Taking into account the inconsistent reporting within available literature, for BMP usage in ACDF, doses lower than 0.7 mg per level can achieve equal successful fusion rates as higher doses, and there is no complication-free dose proved yet. It seems that the lower the dose the lower the incidence of serious complications. As for non-BMP osteobiologics the studies are very limited for each osteobiologic and thus conclusions must be drawn individually and with caution.