Conventional manual discectomy versus powered discectomy for interbody fusion in the lumbar spine: cadaveric testing in forty levels.

STUDY DESIGN

A discectomy study on human cadaveric lumbar spine.

OBJECTIVE

The purpose of this study was to assess the efficacy of manual versus powered discectomies using a transforaminal lumbar interbody fusion approach.

SUMMARY OF BACKGROUND DATA

To achieve fusion, removal of nucleus tissue and endplate cartilage is essential for preparation of the interbody space. Quantitatively, it has been established that maximal structural graft or implant coverage of the endplates are of critical importance for fusion and subsidence prevention.

METHODS

Twenty levels underwent conventional manual discectomy (group 1) and 20 underwent powered discectomy (group 2) by 3 attending spine surgeons and 2 spine fellows. Each discectomy procedure was analyzed for time and number of instrument passes. Postoperatively, each level was measured grossly and digitally for percentage of appropriate discectomy and endplate preparation. For analysis, the superior and inferior endplate surfaces were divided into ipsilateral and contralateral halves, and ventral and dorsal halves. Each quadrant was then analyzed separately.

RESULTS

A total of 40 discectomies on 9 fresh-frozen cadaver torsos between T12-L1 and L5-S1 were performed in this study. Within each quadrant, the discectomized area was greater in group 2 than in group 1. The largest difference was observed on the contralateral ventral quadrant, group 1 (38.2%) and group 2 (52.4%), respectively (P = 0.012). Average procedure time was also significantly less in group 2 versus group 1 (P = 0.009). Group 2 had an overall increased discectomy and appropriately prepared endplates (46.8%) compared with group 1 (36.3%) (P = 0.025). Significantly fewer instrument passes were seen in group 2 versus group 1 (P < 0.001). Two iatrogenic endplate fractures were observed in group 1 and 1 in group 2.

CONCLUSIONS

In addition to a significantly superior discectomy efficacy, the group 2 had significantly fewer instrument passes and shorter procedure times. In vivo studies are required to further evaluate the differences and cost benefit of this innovative tool.