Three Cases of Indirect Decompression Failure Following Oblique Lumbar Interbody Fusion Requiring Early Direct Posterior Decompression: Analysis of Etiologies and Literature Review.

We present three cases of indirect decompression failure (IDF) following oblique lumbar interbody fusion (OLIF). Additional direct posterior decompression (DPD) was performed within a week of the initial procedure to alleviate persistent or deteriorating symptoms due to nerve compression. The IDF incidence rate among patients with lumbar spinal stenosis who underwent OLIF at our institution was 1.8% (three out of 211 patients). Two elderly women (aged 80 and 81) sustained an endplate injury (EPI) and a minor vertebral fracture, followed by cage subsidence, due to untreated osteoporosis during the perioperative period. This resulted in a 43% and 10% decrease in the cross-sectional spinal canal area (CSA), respectively, compared to the preoperative value, leading to neurological deterioration. The third case involved a 74-year-old man with bony foraminal stenosis that could not be alleviated by OLIF, resulting in residual radiculopathy. The effectiveness of indirect decompression via OLIF procedures for patients with severe central stenosis remains a topic of debate. If it is supposed to be effective, the absence of subsequent cage subsidence following OLIF is considered a crucial prerequisite. Although bony foraminal and lateral recess stenosis were significant risk factors for IDF following OLIF in our case analysis as in previous reports, there are few effective parameters with which to predict IDF. Further studies should establish quantitative and integrated thresholds for the predictive parameters of IDF, particularly in conjunction with preoperative CSA and cross-sectional foraminal area (CFA), the restoration of posterior disc height (PDH) during surgery, the Marchi grading system for cage subsidence, and the severity of osteoporosis as indicated by the CT-Hounsfield unit values.