The efficacy of rhBMP-2 versus autograft for posterolateral lumbar spine fusion in elderly patients

Abstract

Few studies have specifically examined the outcomes following rhBMP-2 usage in patients 65 years and older. The purpose of this retrospective study is to evaluate the efficacy of rhBMP-2 with allograft versus autograft for posterolateral lumbar fusion in patients 65 years and older. One hundred twenty-seven patients were divided into three groups based on fusion material and age. Subjects in group A (n = 34) consisted of patients 65 years and older who received rhBMP-2 and allograft. Group B (n = 52) was composed of patients under 65 years of age with rhBMP-2 and allograft. Subjects in group C (n = 41) were 65 years and older with autograft use. A comparison was made of fusion rate, fusion time (noticed, solid), clinical outcome, VAS, perioperative complications and revision rate between each group. The fusion rate and fusion time were similar in groups A and C; however, these were lower than that observed in group B. Clinical outcomes were similar amongst the groups. There were no significant differences in VAS and perioperative complication rate between groups A and C. In patients 65 years and older, rhBMP-2 with allograft may lead to acceptable fusion rates and fusion times, good clinical outcomes and reduced perioperative complications. The combination of rhBMP-2 with allograft yields equivalent outcomes as autograft in elderly patients undergoing instrumented posterolateral lumbar fusion. Additionally, when compared to patients under 65 years of age undergoing posterolateral lumbar fusion, the use of rhBMP-2 was not sufficient to overcome all aspects of the age-related weakened osteoinductive capacity encountered in elderly patients.

Fig. 1

a Mean VAS scores in each group at the different time intervals. There was a significant difference between subjects over (Group A) and under (Group B) 65 years of age at 2 year follow-up (p = 0.041). Asterisk denotes a statistically significant difference between groups. b Clinical outcomes in the rhBMP-2 groups were better in patients under 65 years of age (92.3% were ‘good’) than in patients greater than 65 years of age (85.3% were ‘good’). This difference was not statistically significant (p = 0.184). c Clinical outcomes in patients over 65 years old were better in the rhBMP-2 group (85.3% were ‘good’) than in the autograft group (73.2% were ‘good’). Again, this difference was not statistically significant (p = 0.414)