Transforaminal endoscopic decompression and uninstrumented allograft lumbar interbody fusion: A feasibility study in patients with end-stage vacuum degenerative disc disease
Introduction
Patients with painful end-stage lumbar degenerative disc disease often complain of a combination of mechanical- and sciatica-type low back and leg pain. Painful collapsed lumbar motion segments may be rigid but may also be subject to vertical and anterolateral instability which may develop due to concomitant severe degeneration of the intervertebral disc and facet joints. This process can lead to the complete structural failure of the motion segment and the loss of its biological function [1]. Pfirman et al. described the MRI appearance of severe disc degeneration [2,3]. In some cases, complete degeneration of the intervertebral disc is apparent on routine lumbar plain film studies or even on CT scans [4]. The vacuum sign is associated with the disappearance of the nucleus pulposus tissue, but the underlying biological mechanism is not known [1]. This type of severe disc degeneration can lead to the development of segmental instability, spinal canal, lateral recess, and foraminal stenosis, and produce degenerative deformity but most importantly - spinal stenosis [5]. In the absence of osteophytes re-stabilizing the spinal segment, a progressive, mechanical axial low back pain syndrome may aggravate the neurogenic claudication symptoms even further by contributing to the patient's disability and deterioration of the quality of life [6].
Clinical scenarios may vary from constant low-grade low back pain, to activity related pain that is provoked in standing position and relieved by lying down suggesting that cyclic vertical loading contributes to dynamic instability and foraminal and lateral recess stenosis causing compression of the nerve roots and the dorsal root ganglion. In addition to pain from the repetitive compression of the dorsal root ganglion due to such dynamic foraminal or extraforaminal compression syndrome may produce symptoms out of proportion to evidence on advanced cross-sectional imaging studies due to chronic inflammation of the dorsal root ganglion which can also be originated from concomitant endplate lesions or the related soft-tissue changes [7]. Muscle spasms and facet join synovitis have been found to be associated with severe low back pain as well [8]. The incidence of disc degeneration induced vertical instability increases with age [5]. Non-operative treatment of this condition can provide good results, but a significant number of patients still require surgical intervention. Surgical treatment of degenerative conditions of the lumbar spine in the elderly can be challenging due to the high risk of postoperative complications, the patients' age, and medical comorbidities [9,10]. Therefore, minimally invasive spine surgery techniques have been advocated because they are associated with lower blood loss, reduced tissue damage with a lower perioperative complication rate, and in some cases with shorter operative times [11].
In addition to lower risk surgical techniques that are associated with a lower burden to the patient, new concepts of treating painful end-stage lumbar degenerative disc disease with and without associated stenosis related symptoms in the elderly have emerged [5,12]. Varga et al. have published clinical result of ten-years series on minimally invasive percutaneous cement discoplasty (PCD) for surgical treatment of pain syndromes due to vacuum disc related vertical and anterolateral instability [5]. While the results with cement discoplasty in the elderly were promising and seemed to provide proof of concept, concerns remain regarding how PCD could affect younger and more active patients in the long run. Therefore, the authors decided to investigate the feasibility of utilizing bone allograft for the interbody fusion procedure in patients in whom a painful end-stage degenerative disc was determined based on conclusive preoperative work-up, and validated by direct visualization during the endoscopic transforaminal intradiscal decompression surgery under local anesthesia with the use of diagnostic provocative- and analgesic injections in the sedated yet awake patient.
In this study, the authors report on clinical outcomes, with the percutaneous transforaminal endoscopic decompression with the adjunctive use of an un-instrumented interbody fusion with the impaction of bone allograft into the lumbar interspace through the endoscopic working cannula. The authors intended to investigate whether this treatment in select patients with painful end-stage degenerative disc disease could decrease disability by not just reducing claudication leg symptoms, but also more reliably treat the low back pain which often ensues postoperatively after endoscopic decompression. Ultimately, the authors wanted to investigate whether the placement of allograft cancellous bone chips into a hollow end-stage degenerative vacuum disc could serve as an adjunct to spinal endoscopy to be considered in those highly select patients, who are either unsuitable for or unwilling to undergo a more aggressive open instrumented decompression fusion procedure.
Section snippets
Patient population
All patients provided informed consent to be included in this case series. This retrospective study included patients that were selected from two different centers: 21 patients were operated on by AD and another eight patients by KUL. Thus, a total of 29 patients, 16 of which were male, and another 13 were female were included in this study. All patients underwent unilateral endoscopic transforaminal decompression for sciatica-type low back and leg pain either due to a herniated disc, or
Results
Descriptive frequencies and crosstabulation analysis showed that most patients underwent surgery at the L4/5 level (13/29) and the L5/S1 level (13/29). Lumbar disc herniation (23/29), including three patients with a recurrent lumbar disc herniation, was by far the most common clinical indication for the endoscopic transforaminal interbody allograft fusion surgery was performed. One additional patient suffered sciatica-type low back and leg pain stemming from disc concomitant herniations at
Discussion
In an attempt to treat patients with end-stage degenerative vacuum disc disease suffering from disabling mechanical low back pain and predominant unilateral claudication symptoms with a simplified outpatient foraminal decompression and interbody fusion procedure, the authors studied the clinical outcomes associated with impaction of cancellous bone allograft chips into the hollow lumbar intervertebral disc space when encountered during routine inside-out endoscopic transforaminal surgery.
Conclusions
Outpatient endoscopic transforaminal foraminal and lateral recess decompression with an adjunctive interbody fusion with cancellous bone allograft is an attractive minimally invasive treatment in select patients suffering from lumbar stenosis related claudication symptoms and disabling mechanical low back pain due to severe advanced lumbar disc degeneration. It is ideally indicated in elderly patients with single-level painful endstage degenerative disc disease. The authors’ clinical results
CRediT authorship contribution statement
Álvaro Dowling: Conceptualization, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Visualization, Writing - original draft, Writing - review & editing. James Gerald Hernández Bárcenas: Data curation, Formal analysis, Investigation, Methodology, Project administration. Kai-Uwe Lewandrowski: Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing - original
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