Sadly conventional open spinal surgery may not provide the benefits desired by the patient. Our experience since 1990 treating failed open discectomy, failed microdiscectomy, failed open decompression and laminectomy, failed Dynesis fusion, failed posterior or anterior lumbar interbody fusion and failed total disc replacement has shown a number of common causes underlying the failure. These include:
• Perineural scarring The nerve may be tethered to the disc wall, boundaries of the foramen such as the pedicles, the Superior Foraminal Ligament, posterior vertebral surface, the facet joint capsule, vertebral shoulder or facet joint osteophytes. The normal exiting or transiting (descending) nerves are mobile within the spinal canal or foramen but once tethered are subject to repeated irritation resulting from repeated resisted traction. This accounts for continuing or recurrent symptoms following surgery where the tethering was either never treated or reformed.
• Osteophytosis The nerve may be drawn medially by the scarring into the pathway of ascending facet joint apical osteophytes resulting in impaction on to the nerve and its irritation with local back, buttock and referred leg pain.
• Abnormal micromovement In the presence of the persistent or recurrent perineural scarring, the increasing "sloppiness" ("Instability") of the disc segment following open discectomy, microdiscectomy or open decompression aggravates the irritation of the nerve producing local back, buttock and referred leg pain.
• High Intensity Zones These sources of noxious breakdown products will cause persistent or recurrent symptoms if the source has not been addressed.
• Residual / Recurrent Protusion Following discectomy a loose fragment from within the disc may shift in to the entry portal used to extirpate the original disc protrusion and cause a recurrent or residual protrusion with recurrent or persistent symptoms. Following Total Disc Replacement or Intervertebral Caged or Grafted fusion residual disc material may remain posteriorly with continuing compression or irritation of the nerves. Similarly, misplaced cage, graft or intervertebral implant will cause the same symptoms.
• Pedicle screw causes. Misplaced pedicle screws or fragments broken off the pedicle in to the foramen may cause impingement on to the exiting nerve. The tethering or impingement can be reduced by removal of the fragment or the tethering.
• Incorrect level Aware state foraminal probing and discography allows the patient to lead the surgeon to the correct discal level causal of the symptoms.
The symptoms of failed back surgery may replicate the predominant presenting symptoms in which case the primary cause of the symptoms was never effectively addressed at the correct level or the source of the pain was at an adjacent level. If the symptoms were diminished following surgery but recurred at an interval then this suggests that perineural scarring has developed following surgery.
Failed Back Surgery presents a therapeutic challenge. The presence of a recurrent disc protrusion may be treated by a revision microdiscectomy. "Instability" in the absence of perineural scarring may be deemed suitable for fusion surgery or Total Disc Replacement. Otherwise most cases will be referred for careful conservative management (Orthopaedic Therapy with core spinal muscle and postural rehabilitation, pain killers, anti-inflammatory and anti-irritation drugs) and Intervertebral Differential Dynamics (IDD) and Therapeutic injections (facet joint injections, root blocks, therapeutic discograms), Chronic Pain Management, Cognitive Behavioural Therapy and Coping courses.
Transforaminal Endoscopic Minimally Invasive Spine Surgery using the discrete targeted solutions of TELDF (Foraminoplasty) with side firing laser ablation of the scarring and osteophytes and supplementary LDD, Annuloplasty and with modification of the internal disc structure and metabolism with Gelstix or ultimately stem cells of contributory adjacent levels, offers an encouraging alternative because the transforaminal endoscopic approach allows the nerve to be thoroughly explored and treated.