Failed lumbar spine surgery syndrome (FBSS) refers to the residual symptoms and signs, such as intractable pain or other discomfort in the lower back, buttocks or lower extremities, after lumbar laminectomy or disc removal and nerve root decompression, or the reappearance or even aggravation of symptoms despite temporary relief. Lu et al. reported the incidence of FBSS to be about 10-40%. Therefore, it has become a major problem for spine surgeons, and as the research continues to deepen, the understanding of it continues to deepen.
The common causes of FBSS include the following.
1. Re-protrusion after discectomy
The literature reports a recurrence rate of 5% to 11% after lumbar discectomy, and the Cinotti study concluded that: recurrent lumbar disc herniation is the main cause of postoperative failure. It is similar to some domestic reports. They analyzed the causes of recurrence may be related to the following factors: surgical technique, the size of the intervertebral disc resection volume, and the history of postoperative lumbar trauma. In case of bleeding from the intravertebral plexus, local compression with threads of brain cotton can be used to stop the bleeding, and the operation should not be performed blindly when the surgical field is not clear, so as not to damage the nerve tissue, and the amount of disc removed should be sufficient, generally 3-5 g is appropriate, and only the protruding or ruptured part of the disc tissue should not be removed. The recurrence rate is higher than that after conventional discectomy when compared with conventional discectomy. The herniated portion is only a concentration of degenerated and fragmented nucleus pulposus near the posterior aspect of the vertebral body. Especially in young patients, the nucleus pulposus tissue contains more water, the nucleus pulposus is glue-like, and it is difficult to remove the nucleus pulposus cleanly. Jin Anmin et al. concluded that the main reasons for incomplete removal of the nucleus pulposus were unclear exposure of the spinal canal, insufficient removal of the degenerated nucleus pulposus tissue or too coarse surgical operation. The residual nucleus pulposus not only aggravates the degeneration due to the postoperative pressure imbalance between the vertebrae and the increase of intervertebral activity, but also tends to prolapse out of the intervertebral space and cause new nerve compression. FBSS may be related to surgical errors, but it may also occur after a correct and thorough surgery. The space left after removal of the disc nucleus pulposus is gradually filled with fibrocartilaginous tissue, and both this fibrocartilaginous tissue and degenerative tissue may protrude into the spinal canal through the fissure of the annulus fibrosus. The Goe study concluded that the increase in segmental activity after total myellectomy was significantly greater than that of partial myellectomy, and that the increase in segmental activity was directly related to the amount of myellectomy and the amount and location of fibrous annuloplasty. Premature underground activity after surgery will affect the healing process of fibrosis and gradual change to dense and stable discs after removal, but functional exercises for the low back and abdominal muscles should be strengthened to increase local stability and to establish a new balance in the soft tissue around the lesion gap.
In addition, it has been reported that about 42% of postoperative disc recurrence cases have a clear history of lumbar trauma. Therefore, after lumbar discectomy, especially in the early postoperative period, attention should be paid to the protection of the lumbar spine to avoid premature and excessive weight bearing and strenuous exercise.
2. Intradural epidural scar growth
Intradural epidural scar hyperplasia is considered to be one of the important causes of FBSS Intradural epidural scar hyperplasia and adhesions are the basic pathological changes of lumbar spinal canal surgery Norht reported that FBSS due to intradural epidural scar hyperplasia accounted for about 5-24%, especially the incidence of percutaneous discectomy was about 14-33%. It is widely believed that the adhesive contraction of the scar will pull the dura and nerve roots and restrict their activities. The nerve roots encircled by the scar are subject to abnormal pulling and squeezing, and the axoplasmic transport, arterial blood supply, and venous return of nerve fibers are affected, and the nerve roots and dorsal ganglia are sensitive to mechanical compression, which will produce a series of symptoms. How does the epidural scar form? What are the factors affecting it? Epidural scarring, also known as epidural
In 1948, Key et al. first proposed the anterior origin theory of fibrosis formation, suggesting that epidural scar tissue originates from the damaged fibrous ring and posterior longitudinal ligament in the anterior part of the spinal canal, and then LaRocca et al. Songer et al. first proposed a three-dimensional theory of fibrosis formation, suggesting that fibrosis around the dura comes from the posteriorly injured sacrospinal muscle and from the anteriorly injured annulus fibrosus and posterior longitudinal ligament, while the anterior adhesions encircle the nerve roots and lead to lateral involvement. Roberston et al. suggested that epidural fibrosis is a natural process after disc surgery, and that the postoperative rupture of the annulus fibrosus allows the residual nucleus pulposus, which contains extremely inflammatory levels of phospholipase A2, to enter the epidural space, causing a series of inflammatory reactions that result in scarring. Sun Kang et al. concluded that trauma-hematoma-proliferation of fibroblasts-contact between scar and dura is the basic link in the formation of peridural fibrosis and adhesions. It has been suggested that in addition to the local origin of fibroblasts from damaged tissues, the hematogenous source is also very important, which means that fibroblasts may partly come from their own mitosis, while more evolve from subendothelial and extravascular cells that migrate out from blood vessels, i.e., mainly from the adjacent mesenchymal cells.
Factors affecting epidural scar formation Inflammatory response due to surgical trauma is an important cause of scar formation. These include: surgical exposure of the Van Veen, repeated stretching and clamping of local tissues, remnants of tissue debris, intraoperative and postoperative epidural hemorrhage and hematoma. Hematomas have been thought to play an important role in dural scar formation: hematomas are mediators of fibroblast chemotactic aggregation, etc., leading to the extension of scar tissue into the spinal canal. There is experimental evidence that the presence of hematoma is directly related to the degree and amount of scar tissue denseness. Deep postoperative wound infection, spondylitis, discitis, and spinal instability are also associated with scar proliferation. dullerud et al. showed that obesity, smoking, and high serum levels of triglyceride acyl and glutamyl transpeptidase are associated with decreased fibrinolytic activity, the latter increasing epidural scar formation. Animal experiments have shown that kyphosis and its pull on posterior tissues can aggravate epidural scar formation, while anterior kyphosis or no tension on local tissues is not conducive to scar formation.
3. Post-discectomy spinal stenosis
Post-discectomy spinal stenosis is a major cause of FBSS. One is that some patients already have combined spinal stenosis before surgery, but the operator only pays attention to the disc herniation and ignores the existence of spinal stenosis, especially the lateral saphenous fossa stenosis, so that the spinal stenosis problem is not released at the same time during surgery. About 37.6% of lumbar disc herniations are combined with spinal stenosis. Therefore, the nerve root and caudal nerve compression by spinal canal stenosis should be fully relieved at the same time as the disc herniation is treated. Secondly, because the removal of the nucleus pulposus of the intervertebral disc causes biomechanical dysfunction such as lumbar instability and aggravates the degenerative changes of the lumbar spine, a large amount of scar formation after total laminectomy can also occur due to fibrous canal stenosis and compression of the nerve causing clinical symptoms.
4, lumbar instability after discectomy
The problem of spinal stability has also received increasing attention, and someone has proposed the theory of Three-Joint Complex, which suggests that two posterior small joints and one anterior intervertebral joint (i.e., intervertebral disc) constitute the three-joint complex and play an important role in the stability of the spine, and either degeneration, trauma, or medical injury can cause the three-joint complex to become involved, which in turn affects the spine through a chain reaction. The triple joint complex can be affected by degeneration, trauma, or medical injury, which in turn affects the stability of the spine through a chain reaction. Scholars at home and abroad have confirmed that damage to the intervertebral disc or nucleus pulposus or after resection inevitably leads to a smaller disc height and narrower intervertebral space, resulting in a decrease in structural stress in the anterior part of the lumbar spine and a rise in structural stress in the posterior part, resulting in abnormal and asymmetric activities in the lumbar spine after bearing, with consequent disruption of the biomechanics of the spine and disruption of the stability of the lumbar spine and causing lumbar instability. Huang et al. reported that lumbar instability accounted for 23.3% of FBSS.
5. Diagnostic errors and omissions
(1) Preoperative undetected extreme posterolateral type disc herniation is one of the important causes of FBSS.
The diagnosis of extreme posterolateral and foraminal disc herniation mainly relies on CT and MRI. When the patient has severe symptoms and obvious signs, and CT and MRI examinations do not find any abnormality in the spinal canal, attention should be paid to observe whether there is disc herniation at the foramen and outside the foramen. The incidence of extreme posterolateral disc herniation is reported by Postacchini to be 2.2% of disc herniations, while Monod reported 3.8%. The majority of this type of disc herniation occurs at L4,5, followed by L3,4, and very rarely at L5,S1.
(2) Omission of a multi-segmental disc herniation, bilateral lesions, surgery on one side only and omission of the other side or omission of other disorders combined in the spinal canal is also a common cause of FBSS.
6. Incorrect localization of the lesion segment
Intraoperative positioning errors, due to the presence of migrated vertebrae in the patient, no careful preoperative film reading, and intraoperative positioning based on bony landmarks structures, lead to incorrect surgical clearance.
7. osteoporosis
Wang et al. reported that about 7-20% of patients with low back pain after lower lumbar spine surgery were caused by osteoporosis. These patients are older and have complex conditions, combined with lumbar disc herniation, lateral saphenous fossa stenosis and osteoporosis. Although the surgery solves the main causative factors, there is also a simultaneous destabilization of the spine, instability of the small articular processes and increased bone resorption, resulting in constant microfractures of the bone, which in turn leads to wedge fractures of the vertebral body, i.e., the pulling waves of the periprosthetic tissues and nociceptive receptor structures, resulting in The residual pain symptoms do not heal for a long time after surgery.
8.Autoimmune reaction
The type I and II collagen, glycoprotein and cartilage endplate matrix of the intervertebral disc tissue are autoantigenic, and there are abnormal cellular and humoral immune reactions in lumbar disc herniation, and the application of corticosteroid drugs such as dexamethasone with immunosuppressive effect has significantly improved the symptoms, which shows that this condition may be related to the autoimmune inflammatory reaction caused by the exposure of autoantigen of the intervertebral disc tissue after surgery.
9.Chemical factors
Surgery causes local blood circulation disruption, partial capillary embolism, local ischemia and hypoxia, enhanced decomposition of sugar, fat and protein, impaired oxidation process, accumulation of acidic metabolites and pain-causing factors, causing chemical reactions, no chemical barriers such as nerve bundle membrane in the nerve roots, thus producing chemical radiculitis and causing pain in the innervation zone.
Xu reported that implantation of gelatin sponge in the lumbar spinal canal can cause nerve root and dural sac compression symptoms because it expands after absorbing blood and can form a fixed hematoma, and it can later transform into fibrous tissue causing spinal stenosis.