Abstract
Adjacent segment disease following lumbar spinal fusion refers to any symptomatic pathology occurring rostral or caudal to a previous fusion. The exact etiology of adjacent segment disease is controversial with evidence implicating increased biomechanical forces on the neighboring functional segmental unit as well as an intrinsic degenerative predisposition in this patient population [1–13]. The popularity of posterior instrumented spinal fusions over the last two decades and an aging population has significantly increased the incidence of adjacent segment disease. These patients can present with debilitating symptoms from stenosis, instability, and spinal imbalance. Surgical intervention traditionally consists of a revision posterior approach with extension of the instrumentation and decompression [14–16]. These surgeries are typically higher risk secondary to longer anesthetic durations, increased blood loss, an older patient population, and higher rate of cerebrospinal fluid leak (CSF) from scar tissue [17]. When adjacent segment disease includes proximal junctional kyphosis (PJK), disability arises from sagittal imbalance. A posterior only approach to correct this imbalance usually requires multiple osteotomies, again increasing the operative risk. Also, an open posterior approach has the potential to further disrupt and destabilize the new spinal levels rostral to the construct. Miwa et al. reported on their experience with posterior lumbar interbody fusions (PLIFs) to treat adjacent segment disease after a single level lumbar fusion and discovered that 44 % of these patients deteriorated again because of recurrent adjacent segment disease [15].