An important factor for cage retropulsion after lumbar interbody fusion——the injury of the posterior part of endplate cranial-adjacent to fusion / 中华骨科杂志

ABSTRACT

Objective To investigate causes and treatment strategy of cage retropulsion after lumbar interbody fusion,in particular the correlations between the injury of the posterior part of endplate cranially adjacent to fusion and cage retropulsion.Methods Data of 7 patients with cage migration after lumbar interbody fusion from August 2011 to July 2014 in our hospital were retrospectively analyzed.There were 4 males and 3 females,aged from 45-74 years (average,53.6 years).All patients took X-ray and CT scans examinations 3 d postoperatively,and they were followed up at 3,6,12 months after operation.The characteristics of the patients and the injury of the endplate adjacent to fusion were analyzed to identify possible risk factors of cage retropulsion.Moreover,corresponding managements were performed and outcomes were recorded.Results All 7 cases of cage retropulsion occurred within 3 months post-operatively (rang,15-67 d).Posterior part of the endplate superiorly neighboring to fusion was found injured on the decompression side in all cases with cage retropulsion,and that led to an increase in the posterior intervertebral space height at the fusion segment.Other factors,including pear-shape type endplate,and improper operative manipulations may add the risk of cage retropulsion.These 7 patients complained mild back pain or no back pain,and received corresponding treatments including bed rest,activity limitation,and oral administration of anti-inflammatory analgesics.The clinical symptoms and degrees of cage retropulsion were not aggravated during follow-up.Conclusion The injury of the posterior margin of end-plate superiorly neighboring to fusion on the decompression side which caused increased posterior intervertebral space height may be key to postoperative cage retropulsion.Prevention of possible iatrogenic injury to the endplate may be effective to reduce the risk of cage retropulsion.