| | Intervention | Mechanism of action, reported efficacy, disadvantages |
| | Percutaneous epidural steroid injections | Steroids (injected into the epidural space) are thought to create a local chemical effect with suppression of inflammatory mediators and/or stabilization of nerve membranes [32–35]. Evidence for epidurals for radicular pain relief is good; however, two more recent systematic reviews by Manchikanti and Benyamin conclude that evidence is variable, insufficient, and fair at best for the use of epidurals in treating persistent discogenic LBP [36–41]. | | Percutaneous intradiscal injections | | | (A) Steroids | (A) Steroids (injected into the disc) are thought to create a local chemical effect within the disc. Conflicting evidence has been reported. Most influential, a double-blinded RCT by Khot and colleagues failed to demonstrate efficacy for steroid use within the disc [42]. Potential concern for chondrotoxicity exists given the chondrocyte-like nature of IVD cells [43, 44]. | | (B) Neurolytics | (B) Neurolytics result in cessation of nerve signal via nerve-lysis. An RCT by Peng et al. showed substantial improvements in pain and disability following intradiscal methylene blue injection [45]. Kim et al. showed significant improvements in pain and function; however, improvements were not consistently sustained past 3 months [46]. Other agents such as chondroitin sulfate, glucosamine, carboxycellulose, and a cephalosporin antibiotic have also been injected showing at most modest efficacy [28]. | | (C) Coagulation | (C) Intradiscal Electrothermal Therapy (IDET) serves to coagulate nerve fibers at targeted radial fissures. There has been lack of consistent evidence to support IDET, with reports citing 40–90% success for achieving at least 50% relief; consequently the therapy has fallen out of favor. In need of more rigorous study, transdiscal biaculoplasty uses a radiofrequency current to accomplish this same goal of coagulation (with simultaneous cooling) [47]. The Ramus Communicans nerve fibers can also be ablated. Malik recently noted evidence of short-term efficacy for Ramus Communicans Ablation [25]. | | (D) Fibrin sealant | (D) Fibrin seeks to treat discogenic pain by sealing painful annular fissures. Some evidence suggests fibrin may help to downregulate microenvironment catabolism, seal annular fissures, and increase disc height [48]. When used in combination it may also serve as a tissue scaffold for cell-based therapies [12, 48]. Though an initial pilot study provided promising results, a more recent multicenter, blinded RCT failed to demonstrate similar efficacy following intradiscal injection of “off the shelf” fibrin producing products [49–51]. In need of further study, autologous fibrin preparations are also being explored. | | (E) Prolotherapy | (E) Dextrose prolotherapy is proposed to produce chemomodulatory effects and promote tissue repair through stimulation of inflammatory and proliferative phases [52, 53]. Intradiscal injection of dextrose has demonstrated improvements in radicular leg pain; however, improvements in axial LBP have not been assessed [52]. Traditionally, entheses sites have been targeted (not within the disc) for the treatment of nonspecific LBP. A systematic review using 5 RCTs and quasi-RCTs found mixed results in terms of pain and disability following prolotherapy in LBP patients [53]. Like other proinflammatory injections, prolotherapy can result in a postinjection painful flare [52]. | | (F) Other biologics | (F) Growth factors (GFs) and platelet-based therapies (platelet-rich plasma (PRP), platelet lysate) are believed to have the ability to desensitize cutaneous nerve endings, decrease tissue catabolism, and promote tissue regeneration. Synergism with resident progenitor cells may result in antinociceptive effects and encourage the proliferation of IVD cells, nuclear matrix, and annular collagen [54–57]. Solitary growth factors appear to differ in their anti-inflammatory properties as well as their ability to induce IVD cell activation and matrix proliferation [55, 58]. Members of the TGF-b superfamily have shown greatest promise; however, other potentials include BMPs, IGF-1, GDFs, EGF, PDGF, and bFGF [55]. Animal studies have provided evidence of decreased inflammatory cells and improved fluid content and disc height in discs injected with PRP [58, 59]. Additionally, PRP injected sooner after disc injury appears superior to injection at a later time [59]. Results of a prospective, double-blinded RCT in humans has yielded statistically significant reductions in both pain and function at one year [60, 61]. Anecdotally, some have chosen to inject these biologics outside of the disc in the epidural space to downregulate somatic fibers and induce disc healing. | | Surgical | | | (A) Decompression | (A) Disc decompression aims to treat discogenic and radicular pain by decompressing herniated disc tissue through tissue removal or ablation [47]. Microdiscectomy, automated percutaneous decompression, laser discectomy, and disc nucleoplasty have been used. Decompression is often used for patients with disc herniation and acute neurologic decline; however, others make use of it in cases of refractory radicular and/or axial pain. A recent systematic review concluded there is limited to fair evidence supporting the use of nucleoplasty for radicular pain [62]. It was shown to be moderately superior to nonsurgical therapy for improvement in back pain in the first 2-3 months; however, it was not statistically superior at 2 years [25]. Other reviews have concluded there is no evidence for its use in cases of isolated axial LBP [62–64]. Laser decompression has gained recent attention, with individual studies reporting good outcomes; however, a systematic review by Singh et al. concluded there is limited evidence to support the use of laser therapy [65, 66]. Collectively, these therapies remove disc tissue and should be utilized prudently because of the risk of accelerated disc degeneration [16]. | | (B) Arthrodesis | (B) Arthodesis involves fusing adjacent vertebral bodies for stability. Mechanism of fusion (osseous, hardware) and level of invasiveness (percutaneous, arthroscopic, laparoscopic, and open) vary. One randomized study reported excellent or good outcomes at 2 years in 46% of surgical patients versus 18% nonsurgical patients [67]. More recently, a review of four high quality studies concluded that fusion is slightly moderately more efficacious than standard nonsurgical therapy, but no better than intensive rehabilitation in terms of pain and function [68]. Reduced spinal mobility and a change in spine mechanics is believed to contribute to pain recurrence and an increased incidence of adjacent disc segment degeneration (ASD) (23–43%). Risks of infection, epidural fibrosis, postlaminectomy syndrome, and hardware malfunction have also been reported [8, 27, 69, 70]. | | (C) Arthroplasty | (C) Arthroplasty involves substituting native discs with artificial discs. Arthroplasty may be superior to bony fusion with respect to maintaining basic motion and spine mechanics. Prevalence of ASD is reportedly 9% and 6.7% after arthroplasty (compared to 34% and 23.8% for fusion) [69, 70]. A recent systematic review, Jacobs et al. concluded there was no evidence of superiority between disc replacement and fusion surgery [71, 72]. Risks include hardware infection as well as spinal cord damage and nearby tissue inflammation following hardware degeneration [27, 73] |
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