Fig. 2.

Changes in intervertebral disc height Index (DHI) after anular fibrosus (AF) puncture and osteogenic protein 1 (OP-1) injection. 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 analysis of variance (ANOVA)]. This significant difference in mean %DHI was maintained during the follow-up period (P < 0.001). (From ref. 62, with permission)62