Fig. 4.

Changes in intervertebral disc height index (DHI) after anular puncture and OP-1 injection (with permission, Masuda K et al. (2006) Spine, 31:742–754). The percent DHI (%DHI = [postoperative DHI/preoperative DHI] × 100) was measured at each time point to quantify changes in disc height. By 4 weeks after the OP-1 injection, the mean %DHI of injected discs in the OP-1 group was significantly higher than that in the lactose control group (P<0.001, repeated ANOVA). This significant difference in mean %DHI was maintained during the follow-up period (P<0.001)