Spinal subdural hematoma (SSDH) is an uncommon complication of spinal decompression. SSDH is classified as either acute with sudden back pain or rapid symptom progression, subacute with >1-week symptom progression, or chronic with symptom progression over months to years. There has been only one prior reported case of acute SSDH, following decompression and fusion with this patient presenting with bilaterally lower extremity pain and weakness. There are only four reported cases of SSDH related to spinal surgery, all of which are subacute or chronic in nature, and none of which included fusion. Although durotomy is a relatively well-known complication of decompressive laminectomy, ranging in prevalence from 1.6% to 14%, its association with subsequent or concurrent SSDH in the setting of arthrodesis is exceedingly rare. We present a case of acute SSDH, presenting with cauda equina after surgical decompression and reconstruction, as well as summarize the current literature on SSDH. (Ali Z, Acute Spinal Subdural Hematoma Subsequent to Posterior Lumbar Fusion) Innovations are new idea, device or process. Innovations are the application of better solutions that meet new requirements, inarticulate needs or existing market needs. It is proficient through more effective products, processes, services, technologies, or new ideas that are readily available to markets, governments and society. Innovations are something original and novel, as a significant, new that breaks into the market or society.